Solved: (a) Cholesterol isolated from natural sources is enantiopure. The observed

Which of the following schematic drawings best describes a solution of Li2SO4 in water (water molecules not shown for simplicity)? [Section 4.1]

Aqueous solutions of three different substances, AX, AY, and AZ, are represented by the three accompanying diagrams. Identify each substance as a strong electrolyte, a weak electrolyte, or a nonelectrolyte. [Section 4.1]

Aqueous solutions of three different substances, AX, AY, and AZ, are represented by the three accompanying diagrams. Identify each substance as a strong electrolyte, a weak electrolyte, or a nonelectrolyte. [Section 4.1]

The concept of chemical equilibrium is very important. Which one of the following statements is the most correct way to think about equilibrium? (a) If a system is at equilibrium, nothing is happening. (b) If a system is at equilibrium, the rate of the forward reaction is equal to the rate of the back reaction. (c) If a system is at equilibrium, the product concentration is changing over time. [Section 4.1]

You are presented with a white solid and told that due to careless labeling it is not clear if the substance is barium chloride, lead chloride, or zinc chloride. When you transfer the solid to a beaker and add water, the solid dissolves to give a clear solution. Next a Na2SO4(aq) solution is added and a white precipitate forms. What is the identity of the unknown white solid? [Section 4.2]

Which of the following ions will always be a spectator ion in a precipitation reaction? (a) Cl-, (b) NO3-, (c) NH4+, (d) S2-, (e) SO42-. [Section 4.2]

The labels have fallen off three bottles containing powdered samples of metals; one contains zinc, one lead, and the other platinum. You have three solutions at your disposal: 1 M sodium nitrate, 1 M nitric acid, and 1 M nickel nitrate. How could you use these solutions to determine the identities of each metal powder? [Section 4.4]

Explain how a redox reaction involves electrons in the same way that a neutralization reaction involves protons. [Sections 4.3 and 4.4]

What kind of reaction is the “water-splitting” reaction? \(\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{H}_{2}(g)+1 / 2 \mathrm{O}_{2}(g)\) (a) an acid-base reaction (b) a metathesis reaction (c) a redox reaction (d) a precipitation reaction [Section 4.4] Text Transcription: H_2O(l) longrightarrow H_2(g)+1/2O_2(g)

An aqueous solution contains 1.2 mM of total ions. (a) If the solution is NaCl(aq), what is the concentration of chloride ions? (b) If the solution is FeCl3(aq), what is the concentration of chloride ions? [Section 4.5]

Which data set, of the two graphed here, would you expect to observe from a titration like that shown in Figure 4.18? [Section 4.6]

You are titrating an acidic solution with a basic one, and just realized you forgot to add the indicator that tells you when the equivalence point is reached. In this titration, the indicator turns blue at the equivalence point from an initially colorless solution. You quickly grab a bottle of indicator and add some to your titration beaker, and the whole solution turns dark blue. What do you do now? [Section 4.6]

State whether each of the following statements is true or false. Justify your answer in each case. (a) Electrolyte solutions conduct electricity because electrons are moving through the solution. (b) If you add a nonelectrolyte to an aqueous solution that already contains an electrolyte, the electrical conductivity will not change.

State whether each of the following statements is true or false. Justify your answer in each case. (a) When methanol, CH3OH, is dissolved in water, a conducting solution results. (b) When acetic acid, CH3COOH, dissolves in water, the solution is weakly conducting and acidic in nature.

We have learned in this chapter that many ionic solids dissolve in water as strong electrolytes; that is, as separated ions in solution. Which statement is most correct about this process? (a) Water is a strong acid and therefore is good at dissolving ionic solids. (b) Water is good at solvating ions because the hydrogen and oxygen atoms in water molecules bear partial charges. (c) The hydrogen and oxygen bonds of water are easily broken by ionic solids.

Would you expect that an anion would be physically closer to the oxygen or to the hydrogens of water molecules that surround it in solution?

Specify what ions are present in solution upon dissolving each of the following substances in water: (a) FeCl2, (b) HNO3, (c) (NH4)2SO4, (d) Ca(OH)2.

Specify what ions are present upon dissolving each of the following substances in water: (a) MgI2, (b) K2CO3, (c) HClO4, (d) NaCH3COO.

Formic acid, HCOOH, is a weak electrolyte. What solutes are present in an aqueous solution of this compound? Write the chemical equation for the ionization of HCOOH.

Acetone, CH3COCH3, is a nonelectrolyte; hypochlorous acid, HClO, is a weak electrolyte; and ammonium chloride, NH4Cl, is a strong electrolyte. (a) What are the solutes present in aqueous solutions of each compound? (b) If 0.1 mol of each compound is dissolved in solution, which one contains 0.2 mol of solute particles, which contains 0.1 mol of solute particles, and which contains somewhere between 0.1 and 0.2 mol of solute particles?

Using solubility guidelines, predict whether each of the following compounds is soluble or insoluble in water: (a) MgBr2, (b) PbI2, (c) (NH4)2CO3, (d) Sr(OH)2, (e) ZnSO4.

Predict whether each of the following compounds is soluble in water: (a) AgI, (b) Na2CO3, (c) BaCl2, (d) Al(OH)3, (e) Zn(CH3COO)2.

Will precipitation occur when the following solutions are mixed? If so, write a balanced chemical equation for the reaction. (a) Na2CO3 and AgNO3, (b) NaNO3 and NiSO4, (c) FeSO4 and Pb(NO3)2.

Identify the precipitate (if any) that forms when the following solutions are mixed, and write a balanced equation for each reaction. (a) NaCH3COO and HCl, (b) KOH and Cu(NO3)2, (c) Na2S and CdSO4.

Which ions remain in solution, unreacted, after each of the following pairs of solutions is mixed? (a) potassium carbonate and magnesium sulfate (b) lead nitrate and lithium sulfide (c) ammonium phosphate and calcium chloride

Write balanced net ionic equations for the reactions that occur in each of the following cases. Identify the spectator ion or ions in each reaction. (a) \(\mathrm{Cr}_{2}\left(\mathrm{SO}_{4}\right)_{3}(a q)+\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}(a q) \longrightarrow\) (b) \(\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{K}_{2} \mathrm{SO}_{4}(a q) \longrightarrow\) (c) \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{KOH}(a q) \longrightarrow\) Text Transcription: Cr_2(SO_4)_3(aq)+(NH_4)_2CO_3(aq) longrightarrow Ba(NO_3)_2(aq)+K_2SO_4(aq) longrightarrow Fe(NO_3)_2(aq)+KOH(aq) longrightarrow

Separate samples of a solution of an unknown salt are treated with dilute solutions of HBr, H2SO4, and NaOH. A precipitate forms in all three cases. Which of the following cations could be present in the unknown salt solution: K+, Pb2+, Ba2+?

Separate samples of a solution of an unknown ionic compound are treated with dilute AgNO3, Pb(NO3)2, and BaCl2. Precipitates form in all three cases. Which of the following could be the anion of the unknown salt: Br-, CO32-, NO3-?

You know that an unlabeled bottle contains an aqueous solution of one of the following: AgNO3, CaCl2, or Al2(SO4)3. A friend suggests that you test a portion of the solution with Ba(NO3)2 and then with NaCl solutions. According to your friend’s logic, which of these chemical reactions could occur, thus helping you identify the solution in the bottle? (a) Barium sulfate could precipitate. (b) Silver chloride could precipitate. (c) Silver sulfate could precipitate. (d) More than one, but not all, of the reactions described in answers a–c could occur. (e) All three reactions described in answers a–c could occur.

Three solutions are mixed together to form a single solution; in the final solution, there are 0.2 mol Pb(CH3COO)2, 0.1 mol Na2S, and 0.1 mol CaCl2 present. What solid(s) will precipitate?

Which of the following solutions is the most acidic? (a) 0.2 M LiOH, (b) 0.2 M HI, (c) 1.0 M methanol (CH3OH).

Which of the following solutions is the most basic? (a) 0.6 M NH3, (b) 0.150 M KOH, (c) 0.100 M Ba(OH)2.

State whether each of the following statements is true or false. Justify your answer in each case. (a) Sulfuric acid is a monoprotic acid. (b) HCl is a weak acid. (c) Methanol is a base.

State whether each of the following statements is true or false. Justify your answer in each case. (a) NH3 contains no OH- ions, and yet its aqueous solutions are basic. (b) HF is a strong acid. (c) Although sulfuric acid is a strong electrolyte, an aqueous solution of H2SO4 contains more HSO4- ions than SO42-ions.

Label each of the following substances as an acid, base, salt, or none of the above. Indicate whether the substance exists in aqueous solution entirely in molecular form, entirely as ions, or as a mixture of molecules and ions. (a) HF, (b) acetonitrile, CH3CN, (c) NaClO4, (d) Ba(OH)2.

An aqueous solution of an unknown solute is tested with litmus paper and found to be acidic. The solution is weakly conducting compared with a solution of NaCl of the same concentration. Which of the following substances could the unknown be: KOH, NH3, HNO3, KClO2, H3PO3, CH3COCH3 (acetone)?

Classify each of the following substances as a nonelectrolyte, weak electrolyte, or strong electrolyte in water: (a) H2SO3, (b) CH3CH2OH (ethanol), (c) NH3, (d) KClO3, (e) Cu(NO3)2.

Classify each of the following aqueous solutions as a nonelectrolyte, weak electrolyte, or strong electrolyte: (a) LiClO4, (b) HClO, (c) CH3CH2CH2OH (propanol), (d) HClO3, (e) CuSO4, (f) C12H22O11 (sucrose).

Complete and balance the following molecular equations, and then write the net ionic equation for each: (a) \(\mathrm{HBr}(a q)+\mathrm{Ca}(\mathrm{OH})_{2}(a q) \longrightarrow\) (b) \(\mathrm{Cu}(\mathrm{OH})_{2}(s)+\mathrm{HClO}_{4}(a q) \longrightarrow\) (c) \(\mathrm{Al}(\mathrm{OH})_{3}(s)+\mathrm{HNO}_{3}(a q) \longrightarrow\) Text Transcription: HBr(aq)+Ca(OH)_2(aq) longrightarrow Cu(OH)_2(s)+HClO_4(aq) longrightarrow Al(OH)_3(s)+HNO_3(aq) longrightarrow

Write the balanced molecular and net ionic equations for each of the following neutralization reactions: (a) Aqueous acetic acid is neutralized by aqueous barium hydroxide. (b) Solid chromium(III) hydroxide reacts with nitrous acid. (c) Aqueous nitric acid and aqueous ammonia react.

Write balanced molecular and net ionic equations for the following reactions, and identify the gas formed in each: (a) solid cadmium sulfide reacts with an aqueous solution of sulfuric acid; (b) solid magnesium carbonate reacts with an aqueous solution of perchloric acid.

Because the oxide ion is basic, metal oxides react readily with acids. (a) Write the net ionic equation for the following reaction: \(\mathrm{FeO}(s)+2 \mathrm{HClO}_{4}(a q) \longrightarrow \mathrm{Fe}\left(\mathrm{ClO}_{4}\right)_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l)\) (b) Based on the equation in part (a), write the net ionic equation for the reaction that occurs between NiO(s) and an aqueous solution of nitric acid. Text Transcription: FeO}(s)+2HClO_4(aq) longrightarrow Fe(ClO_4)_2(aq)+H_2O(l)

Magnesium carbonate, magnesium oxide, and magnesium hydroxide are all white solids that react with acidic solutions. (a) Write a balanced molecular equation and a net ionic equation for the reaction that occurs when each substance reacts with a hydrochloric acid solution. (b) By observing the reactions in part (a), how could you distinguish any of the three magnesium substances from the other two?

As K2O dissolves in water, the oxide ion reacts with water molecules to form hydroxide ions. (a) Write the molecular and net ionic equations for this reaction. (b) Based on the definitions of acid and base, what ion is the base in this reaction? (c) What is the acid in the reaction? (d) What is the spectator ion in the reaction?

True or false: (a) If a substance is oxidized, it is gaining electrons. (b) If an ion is oxidized, its oxidation number increases.

True or false: (a) Oxidation can occur without oxygen. (b) Oxidation can occur without reduction.

(a) Which region of the periodic table shown here contains elements that are easiest to oxidize? (b) Which region contains the least readily oxidized elements?

Determine the oxidation number of sulfur in each of the following substances: (a) barium sulfate, BaSO4, (b) sulfurous acid, H2SO3, (c) strontium sulfide, SrS, (d) hydrogen sulfide, H2S. (e) Locate sulfur in the periodic table in Exercise 4.47; what region is it in? (f) Which region(s) of the periodic table contains elements that can adopt both positive and negative oxidation numbers?

Determine the oxidation number for the indicated element in each of the following substances: (a) S in SO2, (b) C in COCl2, (c) Mn in KMnO4, (d) Br in HBrO, (e) P in PF3, (f) O in K2O2.

Determine the oxidation number for the indicated element in each of the following compounds: (a) Co in LiCoO2, (b) Al in NaAlH4, (c) C in CH3OH (methanol), (d) N in GaN, (e) Cl in HClO2, (f) Cr in BaCrO4.

Which element is oxidized, and which is reduced in the following reactions? (a) \(\mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{NH}_{3}(g)\) (b) \(3 \mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{Al}(s) \longrightarrow\) \(3 \mathrm{Fe}(s)+2 \mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}(a q)\) (c) \(\mathrm{Cl}_{2}(a q)+2 \mathrm{NaI}(a q) \longrightarrow \mathrm{I}_{2}(a q)+2 \mathrm{NaCl}(a q)\) (d) \(\mathrm{PbS}(s)+4 \mathrm{H}_{2} \mathrm{O}_{2}(a q) \longrightarrow \mathrm{PbSO}_{4}(s)+4 \mathrm{H}_{2} \mathrm{O}(l)\) Text Transcription: N_2(g)+3H_2(g) longrightarrow 2NH_3(g) 3Fe(NO_3)_2(aq)+2Al(s) longrightarrow 3Fe(s)+2Al(NO_3)_3(a q) Cl_2(aq)+2NaI(aq) longrightarrow I_2(aq)+2NaCl(aq) PbS(s)+4H_2 O_2(aq) longrightarrow PbSO_4(s)+4H_2O(l)

Which of the following are redox reactions? For those that are, indicate which element is oxidized and which is reduced. For those that are not, indicate whether they are precipitation or neutralization reactions. (a) \(\mathrm{P}_{4}(s)+10 \mathrm{HClO}(a q)+6 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow\) \(4 \mathrm{H}_{3} \mathrm{PO}_{4}(a q)+10 \mathrm{HCl}(a q)\) (b) \(\mathrm{Br}_{2}(l)+2 \mathrm{~K}(s) \longrightarrow 2 \mathrm{KBr}(s)\) (c) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}(l)+3 \mathrm{O}_{2}(g) \longrightarrow 3 \mathrm{H}_{2} \mathrm{O}(l)+2 \mathrm{CO}_{2}(g)\) (d) \(\mathrm{ZnCl}_{2}(a q)+2 \mathrm{NaOH}(a q) \longrightarrow \mathrm{Zn}(\mathrm{OH})_{2}(s)+\) \(2 \mathrm{NaCl}(a q)\) Text Transcription: P_4(s)+10HClO(aq)+6H_2O(l) longrightarrow 4H_3PO_4(aq)+10HCl(aq) Br_2(l)+2K(s) longrightarrow 2KBr(s) CH_3CH_2OH(l)+3O_2(g) longrightarrow 3H_2O(l)+2CO_2(g) ZnCl_2(aq)+2NaOH(aq) longrightarrow Zn(OH)_2(s)+ 2NaCl(aq)

Write balanced molecular and net ionic equations for the reactions of (a) manganese with dilute sulfuric acid, (b) chromium with hydrobromic acid, (c) tin with hydrochloric acid, (d) aluminum with formic acid, HCOOH.

Write balanced molecular and net ionic equations for the reactions of (a) hydrochloric acid with nickel, (b) dilute sulfuric acid with iron, (c) hydrobromic acid with magnesium, (d) acetic acid, CH3COOH, with zinc.

Using the activity series (Table 4.5), write balanced chemical equations for the following reactions. If no reaction occurs, write NR. (a) Iron metal is added to a solution of copper(II) nitrate, (b) zinc metal is added to a solution of magnesium sulfate, (c) hydrobromic acid is added to tin metal, (d) hydrogen gas is bubbled through an aqueous solution of nickel(II) chloride, (e) aluminum metal is added to a solution of cobalt(II) sulfate.

Using the activity series (Table 4.5), write balanced chemical equations for the following reactions. If no reaction occurs, write NR. (a) Nickel metal is added to a solution of copper(II) nitrate, (b) a solution of zinc nitrate is added to a solution of magnesium sulfate, (c) hydrochloric acid is added to gold metal, (d) chromium metal is immersed in an aqueous solution of cobalt(II) chloride, (e) hydrogen gas is bubbled through a solution of silver nitrate.

The metal cadmium tends to form Cd2+ ions. The following observations are made: (i) When a strip of zinc metal is placed in CdCl2(aq), cadmium metal is deposited on the strip. (ii) When a strip of cadmium metal is placed in Ni(NO3)2(aq), nickel metal is deposited on the strip. (a) Write net ionic equations to explain each of the preceding observations. (b) Which elements more closely define the position of cadmium in the activity series? (c) What experiments would you need to perform to locate more precisely the position of cadmium in the activity series?

The following reactions (note that the arrows are pointing only one direction) can be used to prepare an activity series for the halogens: \(\mathrm{Br}_{2}(a q)+2 \mathrm{NaI}(a q) \longrightarrow 2 \mathrm{NaBr}(a q)+\mathrm{I}_{2}(a q)\) \(\mathrm{Cl}_{2}(a q)+2 \mathrm{NaBr}(a q) \longrightarrow 2 \mathrm{NaCl}(a q)+\mathrm{Br}_{2}(a q)\) (a) Which elemental halogen would you predict is the most stable, upon mixing with other halides? (b) Predict whether a reaction will occur when elemental chlorine and potassium iodide are mixed. (c) Predict whether a reaction will occur when elemental bromine and lithium chloride are mixed. Text Transcription: Br_2(aq)+2NaI(aq) longrightarrow 2NaBr(aq)+I_2(aq) Cl_2(aq)+2NaBr(aq) longrightarrow 2NaCl(aq)+Br_2(aq)

(a) Is the concentration of a solution an intensive or an extensive property? (b) What is the difference between 0.50 mol HCl and 0.50 M HCl?

You make 1.000 L of an aqueous solution that contains 35.0 g of sucrose (C12H22O11). (a) What is the molarity of sucrose in this solution? (b) How many liters of water would you have to add to this solution to reduce the molarity you calculated in part (a) by a factor of two?

(a) Calculate the molarity of a solution that contains 0.175 mol ZnCl2 in exactly 150 mL of solution. (b) How many moles of protons are present in 35.0 mL of a 4.50 M solution of nitric acid? (c) How many milliliters of a 6.00 M NaOH solution are needed to provide 0.350 mol of NaOH?

(a) Calculate the molarity of a solution made by dissolving 12.5 grams of Na2CrO4 in enough water to form exactly 750 mL of solution. (b) How many moles of KBr are present in 150 mL of a 0.112 M solution? (c) How many milliliters of 6.1 M HCl solution are needed to obtain 0.150 mol of HCl?

The average adult human male has a total blood volume of 5.0 L. If the concentration of sodium ion in this average individual is 0.135 M, what is the mass of sodium ion circulating in the blood?

A person suffering from hyponatremia has a sodium ion concentration in the blood of 0.118 M and a total blood volume of 4.6 L. What mass of sodium chloride would need to be added to the blood to bring the sodium ion concentration up to 0.138 M, assuming no change in blood volume?

The concentration of alcohol (CH3CH2OH) in blood, called the “blood alcohol concentration” or BAC, is given in units of grams of alcohol per 100 mL of blood. The legal definition of intoxication, in many states of the United States, is that the BAC is 0.08 or higher. What is the concentration of alcohol, in terms of molarity, in blood if the BAC is 0.08?

The average adult male has a total blood volume of 5.0 L. After drinking a few beers, he has a BAC of 0.10 (see Exercise 4.65). What mass of alcohol is circulating in his blood?

(a) How many grams of ethanol, CH3CH2OH, should you dissolve in water to make 1.00 L of vodka (which is an aqueous solution that is 6.86 M ethanol)? (b) Using the density of ethanol (0.789 g/mL), calculate the volume of ethanol you need to make 1.00 L of vodka.

One cup of fresh orange juice contains 124 mg of ascorbic acid (vitamin C, C6H8O6). Given that one cup = 236.6 mL, calculate the molarity of vitamin C in orange juice.

(a) Which will have the highest concentration of potassium ion: 0.20 M KCl, 0.15 M K2CrO4, or 0.080 M K3PO4? (b) Which will contain the greater number of moles of potassium ion: 30.0 mL of 0.15 M K2CrO4 or 25.0 mL of 0.080 M K3PO4?

In each of the following pairs, indicate which has the higher concentration of I - ion: (a) 0.10 M BaI2 or 0.25 M KI solution, (b) 100 mL of 0.10 M KI solution or 200 mL of 0.040 M ZnI2 solution, (c) 3.2 M HI solution or a solution made by dissolving 145 g of NaI in water to make 150 mL of solution.

Indicate the concentration of each ion or molecule present in the following solutions: (a) 0.25 M NaNO3, (b) 1.3 10-2 M MgSO4, (c) 0.0150 M C6H12O6, (d) a mixture of 45.0 mL of 0.272 M NaCl and 65.0 mL of 0.0247 M (NH4)2CO3. Assume that the volumes are additive.

Indicate the concentration of each ion present in the solution formed by mixing (a) 42.0 mL of 0.170 M NaOH with 37.6 mL of 0.400 M NaOH, (b) 44.0 mL of 0.100 M Na2SO4 with 25.0 mL of 0.150 M KCl, (c) 3.60 g KCl in 75.0 mL of 0.250 M CaCl2 solution. Assume that the volumes are additive.

(a) You have a stock solution of 14.8 M NH3. How many milliliters of this solution should you dilute to make 1000.0 mL of 0.250 M NH3? (b) If you take a 10.0-mL portion of the stock solution and dilute it to a total volume of 0.500 L, what will be the concentration of the final solution?

(a) How many milliliters of a stock solution of 6.0 M HNO3 would you have to use to prepare 110 mL of 0.500 M HNO3? (b) If you dilute 10.0 mL of the stock solution to a final volume of 0.250 L, what will be the concentration of the diluted solution?

The drug stock solution concentration is 1.5 10-9 M, and 1.00 mL of this solution will be delivered to a dish containing 2.0 105 cancer cells in 5.00 mL of aqueous fluid. What is the ratio of drug molecules to the number of cancer cells in the dish?

Calicheamicin gamma-1, C55H74IN3O21S4, is one of the most potent antibiotics known: one molecule kills one bacterial cell. Describe how you would (carefully!) prepare 25.00 mL of an aqueous calicheamicin gamma-1 solution that could kill 1.0 108 bacteria, starting from a 5.00 10-9M stock solution of the antibiotic.

Pure acetic acid, known as glacial acetic acid, is a liquid with a density of 1.049 g/mL at 25 °C. Calculate the molarity of a solution of acetic acid made by dissolving 20.00 mL of glacial acetic acid at 25 °C in enough water to make 250.0 mL of solution.

Glycerol, C3H8O3, is a substance used extensively in the manufacture of cosmetics, foodstuffs, antifreeze, and plastics. Glycerol is a water-soluble liquid with a density of 1.2656 g/mL at 15 °C. Calculate the molarity of a solution of glycerol made by dissolving 50.000 mL glycerol at 15 °C in enough water to make 250.00 mL of solution.

You want to analyze a silver nitrate solution. (a) You could add HCl(aq) to the solution to precipitate out AgCl(s). What volume of a 0.150 M HCl(aq) solution is needed to precipitate the silver ions from 15.0 mL of a 0.200 M AgNO3 solution? (b) You could add solid KCl to the solution to precipitate out AgCl(s). What mass of KCl is needed to precipitate the silver ions from 15.0 mL of 0.200 M AgNO3 solution? (c) Given that a 0.150 M HCl(aq) solution costs $39.95 for 500 mL and that KCl costs $10/ton, which analysis procedure is more cost-effective?

You want to analyze a cadmium nitrate solution. What mass of NaOH is needed to precipitate the Cd2+ ions from 35.0 mL of 0.500 M Cd(NO3)2 solution?

(a) What volume of 0.115 M HClO4 solution is needed to neutralize 50.00 mL of 0.0875 M NaOH? (b) What volume of 0.128 M HCl is needed to neutralize 2.87 g of Mg(OH)2? (c) If 25.8 mL of an AgNO3 solution is needed to precipitate all the Cl- ions in a 785-mg sample of KCl (forming AgCl), what is the molarity of the AgNO3 solution? (d) If 45.3 mL of a 0.108 M HCl solution is needed to neutralize a solution of KOH, how many grams of KOH must be present in the solution?

(a) How many milliliters of 0.120 M HCl are needed to completely neutralize 50.0 mL of 0.101 M Ba(OH)2 solution? (b) How many milliliters of 0.125 M H2SO4 are needed to neutralize 0.200 g of NaOH? (c) If 55.8 mL of a BaCl2 solution is needed to precipitate all the sulfate ions in a 752-mg sample of Na2SO4, what is the molarity of the BaCl2 solution? (d) If 42.7 mL of 0.208 M HCl solution is needed to neutralize a solution of Ca(OH)2, how many grams of Ca(OH)2 must be in the solution?

Some sulfuric acid is spilled on a lab bench. You can neutralize the acid by sprinkling sodium bicarbonate on it and then mopping up the resulting solution. The sodium bicarbonate reacts with sulfuric acid according to: \(2 \mathrm{NaHCO}_{3}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow \mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\) \(2 \mathrm{H}_{2} \mathrm{O}(l)+2 \mathrm{CO}_{2}(g)\). Sodium bicarbonate is added until the fizzing due to the formation of CO21g2 stops. If 27 mL of 6.0 M H2SO4 was spilled, what is the minimum mass of NaHCO3 that must be added to the spill to neutralize the acid? Text Transcription: 2NaHCO_3(s)+H_2SO_4(aq) longrightarrow Na_2SO_4(aq)+ 2H_2O(l)+2CO_2(g)

The distinctive odor of vinegar is due to acetic acid, CH3COOH, which reacts with sodium hydroxide according to: \(\mathrm{CH}_{3} \mathrm{COOH}(a q)+\mathrm{NaOH}(a q) \longrightarrow\) \(\mathrm{H}_{2} \mathrm{O}(l)+\mathrm{NaCH}_{3} \mathrm{COO}(a q)\). If 3.45 mL of vinegar needs 42.5 mL of 0.115 M NaOH to reach the equivalence point in a titration, how many grams of acetic acid are in a 1.00-qt sample of this vinegar? Text Transcription: CH_3COOH(aq)+NaOH(aq) longrightarrow H_2O(l)+ NaCH_3COO(aq)

A 4.36-g sample of an unknown alkali metal hydroxide is dissolved in 100.0 mL of water. An acid–base indicator is added, and the resulting solution is titrated with 2.50 M HCl(aq) solution. The indicator changes color, signaling that the equivalence point has been reached, after 17.0 mL of the hydrochloric acid solution has been added. (a) What is the molar mass of the metal hydroxide? (b) What is the identity of the alkali metal cation: Li+, Na+, K+, Rb+, or Cs+?

An 8.65-g sample of an unknown group 2A metal hydroxide is dissolved in 85.0 mL of water. An acid–base indicator is added and the resulting solution is titrated with 2.50 M HCl(aq) solution. The indicator changes color, signaling that the equivalence point has been reached, after 56.9 mL of the hydrochloric acid solution has been added. (a) What is the molar mass of the metal hydroxide? (b) What is the identity of the metal cation: Ca2+, Sr2+, or Ba2+?

A solution of 100.0 mL of 0.200 M KOH is mixed with a solution of 200.0 mL of 0.150 M NiSO4. (a) Write the balanced chemical equation for the reaction that occurs. (b) What precipitate forms? (c) What is the limiting reactant? (d) How many grams of this precipitate form? (e) What is the concentration of each ion that remains in solution?

A solution is made by mixing 15.0 g of Sr(OH)2 and 55.0 mL of 0.200 M HNO3. (a) Write a balanced equation for the reaction that occurs between the solutes. (b) Calculate the concentration of each ion remaining in solution. (c) Is the resulting solution acidic or basic?

A 0.5895-g sample of impure magnesium hydroxide is dissolved in 100.0 mL of 0.2050 M HCl solution. The excess acid then needs 19.85 mL of 0.1020 M NaOH for neutralization. Calculate the percentage by mass of magnesium hydroxide in the sample, assuming that it is the only substance reacting with the HCl solution.

A 1.248-g sample of limestone rock is pulverized and then treated with 30.00 mL of 1.035 M HCl solution. The excess acid then requires 11.56 mL of 1.010 M NaOH for neutralization. Calculate the percentage by mass of calcium carbonate in the rock, assuming that it is the only substance reacting with the HCl solution.

Uranium hexafluoride, UF6, is processed to produce fuel for nuclear reactors and nuclear weapons. UF6 is made from the reaction of elemental uranium with ClF3, which also produces Cl2 as a by-product. (a) Write the balanced molecular equation for the conversion of U and ClF3 into UF6 and Cl2. (b) Is this a metathesis reaction? (c) Is this a redox reaction?

The accompanying photo shows the reaction between a solution of Cd(NO3)2 and one of Na2S. (a) What is the identity of the precipitate? (b) What ions remain in solution? (c) Write the net ionic equation for the reaction. (d) Is this a redox reaction?

Suppose you have a solution that might contain any or all of the following cations: Ni2+, Ag+, Sr2+, and Mn2+. Addition of HCl solution causes a precipitate to form. After filtering off the precipitate, H2SO4 solution is added to the resulting solution and another precipitate forms. This is filtered off, and a solution of NaOH is added to the resulting solution. No precipitate is observed. Which ions are present in each of the precipitates? Which of the four ions listed above must be absent from the original solution?

You choose to investigate some of the solubility guidelines for two ions not listed in Table 4.1, the chromate ion (CrO42-) and the oxalate ion (C2O42-). You are given 0.01 M solutions (A, B, C, D) of four water-soluble salts: When these solutions are mixed, the following observations are made: (a) Write a net ionic equation for the reaction that occurs in each of the experiments. (b) Identify the precipitate formed, if any, in each of the experiments.

Antacids are often used to relieve pain and promote healing in the treatment of mild ulcers. Write balanced net ionic equations for the reactions between the aqueous HCl in the stomach and each of the following substances used in various antacids: (a) Al(OH)3(s), (b) Mg(OH)2(s), (c) MgCO3(s), (d) NaAl(CO3)(OH)2(s), (e) CaCO3(s).

The commercial production of nitric acid involves the following chemical reactions: \(4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)\) \(2 \mathrm{NO}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{NO}_{2}(g)\) \(3 \mathrm{NO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow 2 \mathrm{HNO}_{3}(a q)+\mathrm{NO}(g)\) (a) Which of these reactions are redox reactions? (b) In each redox reaction identify the element undergoing oxidation and the element undergoing reduction. (c) How many grams of ammonia must you start with to make 1000.0 L of a 0.150 M aqueous solution of nitric acid? Assume all the reactions give 100% yield. Text Transcription: 4NH_3(g)+5O_2(g) longrightarrow 4NO(g)+6H_2O(g) 2NO(g)+O_2(g) longrightarrow 2NO_2(g) 3NO_2(g)+H_2O(l) longrightarrow 2HNO_3(aq)+NO(g)

Consider the following reagents: zinc, copper, mercury (density 13.6 g/mL), silver nitrate solution, nitric acid solution. (a) Given a 500-mL Erlenmeyer flask and a balloon, can you combine two or more of the foregoing reagents to initiate a chemical reaction that will inflate the balloon? Write a balanced chemical equation to represent this process. What is the identity of the substance that inflates the balloon? (b) What is the theoretical yield of the substance that fills the balloon? (c) Can you combine two or more of the foregoing reagents to initiate a chemical reaction that will produce metallic silver? Write a balanced chemical equation to represent this process. What ions are left behind in solution? (d) What is the theoretical yield of silver?

Bronze is a solid solution of Cu(s) and Sn(s); solutions of metals like this that are solids are called alloys. There is a range of compositions over which the solution is considered a bronze. Bronzes are stronger and harder than either copper or tin alone. (a) A 100.0-g sample of a certain bronze is 90.0% copper by mass and 10.0% tin. Which metal can be called the solvent, and which the solute? (b) Based on part (a), calculate the concentration of the solute metal in the alloy in units of molarity, assuming a density of 7.9 g/cm3. (c) Suggest a reaction that you could do to remove all the tin from this bronze to leave a pure copper sample. Justify your reasoning.

A 35.0-mL sample of 1.00 M KBr and a 60.0-mL sample of 0.600 M KBr are mixed. The solution is then heated to evaporate water until the total volume is 50.0 mL. How many grams of silver nitrate are required to precipitate out silver bromide in the final solution?

Neurotransmitters are molecules that are released by nerve cells to other cells in our bodies, and are needed for muscle motion, thinking, feeling, and memory. Dopamine is a common neurotransmitter in the human brain. (a) Predict what kind of reaction dopamine is most likely to undergo in water: redox, acid-base, precipitation, or metathesis? Explain your reasoning. (b) Patients with Parkinson’s disease suffer from a shortage of dopamine and may need to take it to reduce symptoms. An IV (intravenous fluid) bag is filled with a solution that contains 400.0 mg dopamine per 250.0 mL of solution. What is the concentration of dopamine in the IV bag in units of molarity? (c) Experiments with rats show that if rats are dosed with 3.0 mg/kg of cocaine (that is, 3.0 mg cocaine per kg of animal mass), the concentration of dopamine in their brains increases by 0.75 M after 60 seconds. Calculate how many molecules of dopamine would be produced in a rat (average brain volume 5.00 mm3) after 60 seconds of a 3.0 mg/kg dose of cocaine.

Hard water contains Ca2+, Mg2+, and Fe2+, which interfere with the action of soap and leave an insoluble coating on the insides of containers and pipes when heated. Water softeners replace these ions with Na+. Keep in mind that charge balance must be maintained. (a) If 1500 L of hard water contains 0.020 M Ca2+ and 0.0040 M Mg2+, how many moles of Na+ are needed to replace these ions? (b) If the sodium is added to the water softener in the form of NaCl, how many grams of sodium chloride are needed?

Tartaric acid, H2C4H4O6, has two acidic hydrogens. The acid is often present in wines and a salt derived from the acid precipitates from solution as the wine ages. A solution containing an unknown concentration of the acid is titrated with NaOH. It requires 24.65 mL of 0.2500 M NaOH solution to titrate both acidic protons in 50.00 mL of the tartaric acid solution. Write a balanced net ionic equation for the neutralization reaction, and calculate the molarity of the tartaric acid solution.

(a) A strontium hydroxide solution is prepared by dissolving 12.50 g of Sr(OH)2 in water to make 50.00 mL of solution. What is the molarity of this solution? (b) Next the strontium hydroxide solution prepared in part (a) is used to titrate a nitric acid solution of unknown concentration. Write a balanced chemical equation to represent the reaction between strontium hydroxide and nitric acid solutions. (c) If 23.9 mL of the strontium hydroxide solution was needed to neutralize a 37.5 mL aliquot of the nitric acid solution, what is the concentration (molarity) of the acid?

A solid sample of Zn(OH)2 is added to 0.350 L of 0.500 M aqueous HBr. The solution that remains is still acidic. It is then titrated with 0.500 M NaOH solution, and it takes 88.5 mL of the NaOH solution to reach the equivalence point. What mass of Zn(OH)2 was added to the HBr solution?

Suppose you have 5.00 g of powdered magnesium metal, 1.00 L of 2.00 M potassium nitrate solution, and 1.00 L of 2.00 M silver nitrate solution. (a) Which one of the solutions will react with the magnesium powder? (b) What is the net ionic equation that describes this reaction? (c) What volume of solution is needed to completely react with the magnesium? (d) What is the molarity of the Mg2+ ions in the resulting solution?

(a) By titration, 15.0 mL of 0.1008 M sodium hydroxide is needed to neutralize a 0.2053-g sample of a weak acid. What is the molar mass of the acid if it is monoprotic? (b) An elemental analysis of the acid indicates that it is composed of 5.89% H, 70.6% C, and 23.5% O by mass. What is its molecular formula?

Gold is isolated from rocks by reaction with aqueous cyanide, CN-: \(4 \mathrm{Au}(s)+8 \mathrm{NaCN}(a q)+\mathrm{O}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow\) \(4 \mathrm{Na}\left[\mathrm{Au}(\mathrm{CN})_{2}\right](a q)+4 \mathrm{NaOH}(a q)\). (a) Which atoms from which compounds are being oxidized, and which atoms from which compounds are being reduced? (b) The [Au(CN)2]- ion can be converted back to Au(0) by reaction with Zn(s) powder. Write a balanced chemical equation for this reaction. (c) How many liters of a 0.200 M sodium cyanide solution would be needed to react with 40.0 kg of rocks that contain 2.00% by mass of gold? Text Transcription: 4Au(s)+8NaCN(aq)+O_2(g)+H_2O(l) longrightarrow 4Na[Au(CN)_2](aq)+4NaOH(aq)

A fertilizer railroad car carrying 34,300 gallons of commercial aqueous ammonia (30% ammonia by mass) tips over and spills. The density of the aqueous ammonia solution is 0.88 g/cm3. What mass of citric acid, C(OH)(COOH)(CH2COOH)2, (which contains three acidic protons) is required to neutralize the spill? 1 gallon = 3.785 L.

A sample of 7.75 g of Mg(OH)2 is added to 25.0 mL of 0.200 M HNO3. (a) Write the chemical equation for the reaction that occurs. (b) Which is the limiting reactant in the reaction? (c) How many moles of Mg(OH)2, HNO3, and Mg(NO3)2 are present after the reaction is complete?

In 2014, a major chemical leak at a facility in West Virginia released 7500 gallons of MCHM (4-methylcyclohexyl methanol, C8H16O) into the Elk River. The density of MCHM is 0.9074 g/mL. (a) Calculate the initial molarity of MCHM in the river, assuming that the first part of the river is 7.00 feet deep, 100.0 yards wide, and 100.0 yards long. 1 gallon = 3.785 L. (b) How much farther down the river would the spill have to spread in order to achieve a “safe” MCHM concentration of 1.00 10-4 M? Assume the depth and width of the river are constant and the concentration of MCHM is uniform along the length of the spill.

Ritalin is the trade name of a drug, methylphenidate, used to treat attention-deficit/hyperactivity disorder in young adults. The chemical structure of methylphenidate is (a) Is Ritalin an acid or a base? An electrolyte or a nonelectrolyte? (b) A tablet contains a 10.0-mg dose of Ritalin. Assuming all the drug ends up in the bloodstream, and the average man has a total blood volume of 5.0 L, calculate the initial molarity of Ritalin in a man’s bloodstream. (c) Ritalin has a half-life of 3 hours in the blood, which means that after 3 hours the concentration in the blood has decreased by half of its initial value. For the man in part (b), what is the concentration of Ritalin in his blood after 6 hours?

The mass percentage of chloride ion in a 25.00-mL sample of seawater was determined by titrating the sample with silver nitrate, precipitating silver chloride. It took 42.58 mL of 0.2997 M silver nitrate solution to reach the equivalence point in the titration. What is the mass percentage of chloride ion in seawater if its density is 1.025 g/mL?

The arsenic in a 1.22-g sample of a pesticide was converted to AsO43- by suitable chemical treatment. It was then titrated using Ag+ to form Ag3AsO4 as a precipitate. (a) What is the oxidation state of As in AsO43-? (b) Name Ag3AsO4 by analogy to the corresponding compound containing phosphorus in place of arsenic. (c) If it took 25.0 mL of 0.102 M Ag+ to reach the equivalence point in this titration, what is the mass percentage of arsenic in the pesticide?

The U.S. standard for arsenate in drinking water requires that public water supplies must contain no greater than 10 parts per billion (ppb) arsenic. If this arsenic is present as arsenate, AsO43-, what mass of sodium arsenate would be present in a 1.00-L sample of drinking water that just meets the standard? Parts per billion is defined on a mass basis as \(\mathrm{ppb}=\frac{\mathrm{g} \text { solute }}{\text { g solution }} \times 10^{9}\) Text Transcription: ppb=g solute/g solution times10^9

Federal regulations set an upper limit of 50 parts per million (ppm) of NH3 in the air in a work environment [that is, 50 molecules of NH3(g) for every million molecules in the air]. Air from a manufacturing operation was drawn through a solution containing 1.00 102 mL of 0.0105 M HCl. The NH3 reacts with HCl according to: \(\mathrm{NH}_{3}(a q)+\mathrm{HCl}(a q) \longrightarrow \mathrm{NH}_{4} \mathrm{Cl}(a q)\). After drawing air through the acid solution for 10.0 min at a rate of 10.0 L/min, the acid was titrated. The remaining acid needed 13.1 mL of 0.0588 M NaOH to reach the equivalence point. (a) How many grams of NH3 were drawn into the acid solution? (b) How many ppm of NH3 were in the air? (Air has a density of 1.20 g/L and an average molar mass of 29.0 g/mol under the conditions of the experiment.) (c) Is this manufacturer in compliance with regulations? Text Transcription: NH_3(aq)+HCl(aq) longrightarrow NH_4Cl(aq)

Examine the following for chirality centers:

Identify the chirality centers, if any, in (b) 1,1,2-Trimethylcyclobutane and 1,1,3-Trimethylcyclobutane

Locate any planes of symmetry in each of the following compounds. Which of the compounds are chiral? Which are achiral?

Does the molecular model shown represent (+)-2-butanol or (?)-2-butanol?

Assign absolute configurations as R or S to each of the following compounds:

Draw three-dimensional representations of

What is the absolute configuration (R or S) of the compounds represented by the Fischer projections shown here?

Using the Fischer projection of (R)-2-butanol shown, explain how each of the following affects the configuration of the chirality center. (a) Switching the positions of H and OH. (b) Switching the positions of CH3 and CH2CH3. (c) Switching the positions of three groups. (d) Switching H with OH, and CH3 with CH2CH3. (e) Rotating the Fischer projection 180° around an axis perpendicular to the page.

Assign appropriate R,S symbols to the chirality centers in (?)-nicotine, (?)-adrenaline, and (?)-thyroxine.

The 3,3?-5,5? isomer of the compound just shown has a chirality axis, but its separation into isolable enantiomers would be extremely difficult. Why?

A meso stereoisomer is possible for one of the following compounds. Which one?

A second category of six-carbon carbohydrates, called ketohexoses, has the constitution shown. How many stereoisomeric 2-ketohexoses are possible?

Which of the isomeric alcohols having the molecular formula C6H14O are chiral? Which are achiral?

In each of the following pairs of compounds one is chiral and the other is achiral. Identify each compound as chiral or achiral, as appropriate.

Compare 2,3-pentanediol and 2,4-pentanediol with respect to the number of stereoisomers possible for each. Which ones are chiral? Which are achiral?

Of the isomers shown, which are chiral? Which ones are constitutional isomers of each other? Stereoisomers? Enantiomers? Diastereomers?

Diltiazem is prescribed to treat hypertension, and simvastatin is a cholesterol-lowering drug. Locate the chirality centers in each.

Among compounds (a)–(d), identify those that have a chirality axis. A B X Y (a) (CH3)3C? H? H? H? (b) (CH3)3C? (CH3)3C? H? H? (c) (CH3)3C? H? (CH3)3C? H? (c) (CH3)3C? (CH3)3C? (CH3)3C? (CH3)3C?

The absolute configuration of (?)-bromochlorofluoromethane is R. Which of the following is (are) (?)-BrClFCH?

A subrule of the Cahn–Ingold–Prelog system specifies that higher mass number takes precedence over lower when distinguishing between isotopes. (a) Determine the absolute configurations of the reactant and product in the biological oxidation of isotopically labeled ethane described in Section 4.2. (b) Because OH becomes bonded to carbon at the same side from which H is lost, the oxidation proceeds with retention of configuration. Compare this fact with the R and S configurations you determined in part (a) and reconcile any apparent conflicts.

Specify the configuration of the chirality center as R or S in each of the following. (a) (?)-2-Octanol (b) Monosodium l-glutamate (only this stereoisomer is a flavor-enhancing agent)

The name cis-3-bromocyclohexanol correctly describes the constitution and relative stereochemistry of the compound shown. The molecule, however, is chiral so if we wish to distinguish between it and its enantiomer we need to specify its absolute configuration using R,S notation. Which of the four possibilities is correct? (1R,3R)-3-bromocyclohexanol (1S,3S)-bromocyclohexanol (1R,3S)-3-bromocyclohexanol (1S,3R)-3-bromocyclohexanol

The antiparkinson drug droxidopa has the structural formula shown with configurations at C-2 and C-3 of S and R, respectively. Add appropriate wedges and/or dashes to show the stereochemistry.

Identify the relationship in each of the following pairs. Do the drawings represent constitutional isomers or stereoisomers, or are they just different ways of drawing the same compound? If they are stereoisomers, are they enantiomers or diastereomers?

Muscarine is a poisonous substance present in the mushroom Amanita muscaria. Its structure is represented by the constitution shown here. (a) Including muscarine, how many stereoisomers have this constitution? (b) One of the substituents on the ring of muscarine is trans to the other two. How many of the stereoisomers satisfy this requirement? (c) Muscarine has the configuration 2S,3R,5S. Write a structural formula of muscarine showing its correct stereochemistry.

A certain natural product having \([\alpha]_{\mathrm{D}}\) + 40.3° was isolated. Two very different structures were independently proposed for this compound. Which one do you think is more likely to be correct? Why? Text Transcription: [alpha]_D

One of the principal substances obtained from archaea (one of the oldest forms of life on Earth) is derived from a 40-carbon diol. Given the fact that this diol is optically active, is it compound A or is it compound B?

Consider two chemical changes: one occurring at a tetrahedral sp3 carbon C(x,x,y,z), the other at a trigonal sp2 carbon C(x,y,z), where x, y, and z are different atoms or groups attached to C. Each reactant is achiral; both are converted to the chiral product C(w,x,y,z). In the first case w replaces one of the x atoms or groups, in the other w adds to the trigonal carbon. Both transformations convert C in each achiral reactant to a chirality center in the product. The two achiral reactants are classified as prochiral. C is a prochirality center in C(x,x,y,z) and has two prochiral faces in C(x,y,z). In achiral molecules with tetrahedral prochirality centers, substitution of one of the two x groups by w gives the enantiomer of the product that results from substitution of the other. The two x groups occupy mirror-image sites and are enantiotopic. Enantiotopic groups are designated as pro-R or pro-S by a modification of Cahn–Ingold–Prelog notation. One is assigned a higher priority than the other without disturbing the priorities of the remaining groups, and the R,S configuration of the resulting chirality center is determined in the usual way. If it is R, the group assigned the higher rank is pro-R. If S, this group is pro-S. Ethanol and citric acid illustrate the application of this notation to two prochiral molecules. Citric acid played a major role in the development of the concept of prochirality. Its two CH2CO2H chain groups behave differently in a key step of the Krebs cycle, so differently that some wondered whether citric acid itself was really involved. Alexander Ogston (Oxford) provided the answer in 1948 when he pointed out that the two CH2CO2H groups are differentiated when citric acid interacts with the chiral environment of an enzyme. The two prochiral faces of a trigonal atom C(x,y,z) are enantiotopic and designated Re and Si according to whether x, y, and z trace a clockwise (Re) or counterclockwise (Si) path in order of decreasing Cahn–Ingold–Prelog precedence. An acetaldehyde molecule that lies in the plane of the paper, for example, presents either the Re or Si face according to how it is oriented. The stereochemical aspects of many enzyme-catalyzed reactions have been determined. The enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde by removing the pro-R hydrogen (abbreviated as HR). When the same enzyme catalyzes the reduction of acetaldehyde to ethanol, hydrogen is transferred to the Re face. Which molecule is prochiral? A. Ethane B. Propane C. Butane D. Cyclopropane

Consider two chemical changes: one occurring at a tetrahedral sp3 carbon C(x,x,y,z), the other at a trigonal sp2 carbon C(x,y,z), where x, y, and z are different atoms or groups attached to C. Each reactant is achiral; both are converted to the chiral product C(w,x,y,z). In the first case w replaces one of the x atoms or groups, in the other w adds to the trigonal carbon. Both transformations convert C in each achiral reactant to a chirality center in the product. The two achiral reactants are classified as prochiral. C is a prochirality center in C(x,x,y,z) and has two prochiral faces in C(x,y,z). In achiral molecules with tetrahedral prochirality centers, substitution of one of the two x groups by w gives the enantiomer of the product that results from substitution of the other. The two x groups occupy mirror-image sites and are enantiotopic. Enantiotopic groups are designated as pro-R or pro-S by a modification of Cahn–Ingold–Prelog notation. One is assigned a higher priority than the other without disturbing the priorities of the remaining groups, and the R,S configuration of the resulting chirality center is determined in the usual way. If it is R, the group assigned the higher rank is pro-R. If S, this group is pro-S. Ethanol and citric acid illustrate the application of this notation to two prochiral molecules. Citric acid played a major role in the development of the concept of prochirality. Its two CH2CO2H chain groups behave differently in a key step of the Krebs cycle, so differently that some wondered whether citric acid itself was really involved. Alexander Ogston (Oxford) provided the answer in 1948 when he pointed out that the two CH2CO2H groups are differentiated when citric acid interacts with the chiral environment of an enzyme. The two prochiral faces of a trigonal atom C(x,y,z) are enantiotopic and designated Re and Si according to whether x, y, and z trace a clockwise (Re) or counterclockwise (Si) path in order of decreasing Cahn–Ingold–Prelog precedence. An acetaldehyde molecule that lies in the plane of the paper, for example, presents either the Re or Si face according to how it is oriented. The stereochemical aspects of many enzyme-catalyzed reactions have been determined. The enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde by removing the pro-R hydrogen (abbreviated as HR). When the same enzyme catalyzes the reduction of acetaldehyde to ethanol, hydrogen is transferred to the Re face. How many of the carbons in 2-methylpentane [(CH3)2CHCH2CH2CH3] are prochirality centers? A. One B. Two C. Three D. Four

Consider two chemical changes: one occurring at a tetrahedral sp3 carbon C(x,x,y,z), the other at a trigonal sp2 carbon C(x,y,z), where x, y, and z are different atoms or groups attached to C. Each reactant is achiral; both are converted to the chiral product C(w,x,y,z). In the first case w replaces one of the x atoms or groups, in the other w adds to the trigonal carbon. Both transformations convert C in each achiral reactant to a chirality center in the product. The two achiral reactants are classified as prochiral. C is a prochirality center in C(x,x,y,z) and has two prochiral faces in C(x,y,z). In achiral molecules with tetrahedral prochirality centers, substitution of one of the two x groups by w gives the enantiomer of the product that results from substitution of the other. The two x groups occupy mirror-image sites and are enantiotopic. Enantiotopic groups are designated as pro-R or pro-S by a modification of Cahn–Ingold–Prelog notation. One is assigned a higher priority than the other without disturbing the priorities of the remaining groups, and the R,S configuration of the resulting chirality center is determined in the usual way. If it is R, the group assigned the higher rank is pro-R. If S, this group is pro-S. Ethanol and citric acid illustrate the application of this notation to two prochiral molecules. Citric acid played a major role in the development of the concept of prochirality. Its two CH2CO2H chain groups behave differently in a key step of the Krebs cycle, so differently that some wondered whether citric acid itself was really involved. Alexander Ogston (Oxford) provided the answer in 1948 when he pointed out that the two CH2CO2H groups are differentiated when citric acid interacts with the chiral environment of an enzyme. The two prochiral faces of a trigonal atom C(x,y,z) are enantiotopic and designated Re and Si according to whether x, y, and z trace a clockwise (Re) or counterclockwise (Si) path in order of decreasing Cahn–Ingold–Prelog precedence. An acetaldehyde molecule that lies in the plane of the paper, for example, presents either the Re or Si face according to how it is oriented. The stereochemical aspects of many enzyme-catalyzed reactions have been determined. The enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde by removing the pro-R hydrogen (abbreviated as HR). When the same enzyme catalyzes the reduction of acetaldehyde to ethanol, hydrogen is transferred to the Re face. What are the pro-R and pro-S designations for the enantiotopic hydrogens in 1-propanol?

Consider two chemical changes: one occurring at a tetrahedral sp3 carbon C(x,x,y,z), the other at a trigonal sp2 carbon C(x,y,z), where x, y, and z are different atoms or groups attached to C. Each reactant is achiral; both are converted to the chiral product C(w,x,y,z). In the first case w replaces one of the x atoms or groups, in the other w adds to the trigonal carbon. Both transformations convert C in each achiral reactant to a chirality center in the product. The two achiral reactants are classified as prochiral. C is a prochirality center in C(x,x,y,z) and has two prochiral faces in C(x,y,z). In achiral molecules with tetrahedral prochirality centers, substitution of one of the two x groups by w gives the enantiomer of the product that results from substitution of the other. The two x groups occupy mirror-image sites and are enantiotopic. Enantiotopic groups are designated as pro-R or pro-S by a modification of Cahn–Ingold–Prelog notation. One is assigned a higher priority than the other without disturbing the priorities of the remaining groups, and the R,S configuration of the resulting chirality center is determined in the usual way. If it is R, the group assigned the higher rank is pro-R. If S, this group is pro-S. Ethanol and citric acid illustrate the application of this notation to two prochiral molecules. Citric acid played a major role in the development of the concept of prochirality. Its two CH2CO2H chain groups behave differently in a key step of the Krebs cycle, so differently that some wondered whether citric acid itself was really involved. Alexander Ogston (Oxford) provided the answer in 1948 when he pointed out that the two CH2CO2H groups are differentiated when citric acid interacts with the chiral environment of an enzyme. The two prochiral faces of a trigonal atom C(x,y,z) are enantiotopic and designated Re and Si according to whether x, y, and z trace a clockwise (Re) or counterclockwise (Si) path in order of decreasing Cahn–Ingold–Prelog precedence. An acetaldehyde molecule that lies in the plane of the paper, for example, presents either the Re or Si face according to how it is oriented. The stereochemical aspects of many enzyme-catalyzed reactions have been determined. The enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde by removing the pro-R hydrogen (abbreviated as HR). When the same enzyme catalyzes the reduction of acetaldehyde to ethanol, hydrogen is transferred to the Re face. The enzyme fumarase catalyzes the addition of water to the double bond of fumaric acid. The ? OH group and the pro-R hydrogen of the CH2 group of (S)-(?)malic acid come from water. What stereochemical pathway describes the addition of water to the double bond? A. syn Addition B. anti Addition

Consider two chemical changes: one occurring at a tetrahedral sp3 carbon C(x,x,y,z), the other at a trigonal sp2 carbon C(x,y,z), where x, y, and z are different atoms or groups attached to C. Each reactant is achiral; both are converted to the chiral product C(w,x,y,z). In the first case w replaces one of the x atoms or groups, in the other w adds to the trigonal carbon. Both transformations convert C in each achiral reactant to a chirality center in the product. The two achiral reactants are classified as prochiral. C is a prochirality center in C(x,x,y,z) and has two prochiral faces in C(x,y,z). In achiral molecules with tetrahedral prochirality centers, substitution of one of the two x groups by w gives the enantiomer of the product that results from substitution of the other. The two x groups occupy mirror-image sites and are enantiotopic. Enantiotopic groups are designated as pro-R or pro-S by a modification of Cahn–Ingold–Prelog notation. One is assigned a higher priority than the other without disturbing the priorities of the remaining groups, and the R,S configuration of the resulting chirality center is determined in the usual way. If it is R, the group assigned the higher rank is pro-R. If S, this group is pro-S. Ethanol and citric acid illustrate the application of this notation to two prochiral molecules. Citric acid played a major role in the development of the concept of prochirality. Its two CH2CO2H chain groups behave differently in a key step of the Krebs cycle, so differently that some wondered whether citric acid itself was really involved. Alexander Ogston (Oxford) provided the answer in 1948 when he pointed out that the two CH2CO2H groups are differentiated when citric acid interacts with the chiral environment of an enzyme. The two prochiral faces of a trigonal atom C(x,y,z) are enantiotopic and designated Re and Si according to whether x, y, and z trace a clockwise (Re) or counterclockwise (Si) path in order of decreasing Cahn–Ingold–Prelog precedence. An acetaldehyde molecule that lies in the plane of the paper, for example, presents either the Re or Si face according to how it is oriented. The stereochemical aspects of many enzyme-catalyzed reactions have been determined. The enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde by removing the pro-R hydrogen (abbreviated as HR). When the same enzyme catalyzes the reduction of acetaldehyde to ethanol, hydrogen is transferred to the Re face. To which prochiral face of the double bond of fumaric acid does the OH group add to in the fumarase-catalyzed hydration of fumaric acid described in the preceding problem? A. Re B. Si

Consider two chemical changes: one occurring at a tetrahedral sp3 carbon C(x,x,y,z), the other at a trigonal sp2 carbon C(x,y,z), where x, y, and z are different atoms or groups attached to C. Each reactant is achiral; both are converted to the chiral product C(w,x,y,z). In the first case w replaces one of the x atoms or groups, in the other w adds to the trigonal carbon. Both transformations convert C in each achiral reactant to a chirality center in the product. The two achiral reactants are classified as prochiral. C is a prochirality center in C(x,x,y,z) and has two prochiral faces in C(x,y,z). In achiral molecules with tetrahedral prochirality centers, substitution of one of the two x groups by w gives the enantiomer of the product that results from substitution of the other. The two x groups occupy mirror-image sites and are enantiotopic. Enantiotopic groups are designated as pro-R or pro-S by a modification of Cahn–Ingold–Prelog notation. One is assigned a higher priority than the other without disturbing the priorities of the remaining groups, and the R,S configuration of the resulting chirality center is determined in the usual way. If it is R, the group assigned the higher rank is pro-R. If S, this group is pro-S. Ethanol and citric acid illustrate the application of this notation to two prochiral molecules. Citric acid played a major role in the development of the concept of prochirality. Its two CH2CO2H chain groups behave differently in a key step of the Krebs cycle, so differently that some wondered whether citric acid itself was really involved. Alexander Ogston (Oxford) provided the answer in 1948 when he pointed out that the two CH2CO2H groups are differentiated when citric acid interacts with the chiral environment of an enzyme. The two prochiral faces of a trigonal atom C(x,y,z) are enantiotopic and designated Re and Si according to whether x, y, and z trace a clockwise (Re) or counterclockwise (Si) path in order of decreasing Cahn–Ingold–Prelog precedence. An acetaldehyde molecule that lies in the plane of the paper, for example, presents either the Re or Si face according to how it is oriented. The stereochemical aspects of many enzyme-catalyzed reactions have been determined. The enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde by removing the pro-R hydrogen (abbreviated as HR). When the same enzyme catalyzes the reduction of acetaldehyde to ethanol, hydrogen is transferred to the Re face. A method for the stereoselective synthesis of chiral epoxides gave the product shown in high enantiomeric excess. To which faces of the doubly bonded carbons is oxygen transferred? A. Re Re B. Re Si C. Si Si D. Si Re

Consider two chemical changes: one occurring at a tetrahedral sp3 carbon C(x,x,y,z), the other at a trigonal sp2 carbon C(x,y,z), where x, y, and z are different atoms or groups attached to C. Each reactant is achiral; both are converted to the chiral product C(w,x,y,z). In the first case w replaces one of the x atoms or groups, in the other w adds to the trigonal carbon. Both transformations convert C in each achiral reactant to a chirality center in the product. The two achiral reactants are classified as prochiral. C is a prochirality center in C(x,x,y,z) and has two prochiral faces in C(x,y,z). In achiral molecules with tetrahedral prochirality centers, substitution of one of the two x groups by w gives the enantiomer of the product that results from substitution of the other. The two x groups occupy mirror-image sites and are enantiotopic. Enantiotopic groups are designated as pro-R or pro-S by a modification of Cahn–Ingold–Prelog notation. One is assigned a higher priority than the other without disturbing the priorities of the remaining groups, and the R,S configuration of the resulting chirality center is determined in the usual way. If it is R, the group assigned the higher rank is pro-R. If S, this group is pro-S. Ethanol and citric acid illustrate the application of this notation to two prochiral molecules. Citric acid played a major role in the development of the concept of prochirality. Its two CH2CO2H chain groups behave differently in a key step of the Krebs cycle, so differently that some wondered whether citric acid itself was really involved. Alexander Ogston (Oxford) provided the answer in 1948 when he pointed out that the two CH2CO2H groups are differentiated when citric acid interacts with the chiral environment of an enzyme. The two prochiral faces of a trigonal atom C(x,y,z) are enantiotopic and designated Re and Si according to whether x, y, and z trace a clockwise (Re) or counterclockwise (Si) path in order of decreasing Cahn–Ingold–Prelog precedence. An acetaldehyde molecule that lies in the plane of the paper, for example, presents either the Re or Si face according to how it is oriented. The stereochemical aspects of many enzyme-catalyzed reactions have been determined. The enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde by removing the pro-R hydrogen (abbreviated as HR). When the same enzyme catalyzes the reduction of acetaldehyde to ethanol, hydrogen is transferred to the Re face. When the achiral dione shown (below left) was incubated in water with baker’s yeast, reduction of one of the C=O groups occurred to give a single stereoisomer of the product. This product corresponded to hydrogen transfer to the Re face of the pro-R carbonyl group. Which product is this?

(a) Where is the plane of symmetry in trans-1,3-cyclobutanediol? (b) Does cis-1,3-cyclobutanediol possess a center of symmetry? A plane of symmetry? Is it chiral or achiral?

A sample of the chiral molecule limonene is 95% enantiopure. What percentage of each enantiomer is present? What is the percent enantiomeric excess?

(a) Cholesterol isolated from natural sources is enantiopure. The observed rotation of a 0.3-g sample of cholesterol in 15 mL of chloroform solution contained in a 10-cm polarimeter tube is ?0.78°. Calculate the specific rotation of cholesterol. (b) A sample of synthetic cholesterol consisting entirely of (+)-cholesterol was mixed with some natural (?)-cholesterol. The specific rotation of the mixture was ?13°. What fraction of the mixture was (+)-cholesterol?

Find the chirality center in the molecular model of thalidomide shown above and identify its configuration as R or S.

Assign the R or S configuration to the chirality centers in the four isomeric 2,3-dihydroxybutanoic acids shown in the preceding Fischer projections. Consult Figure 4.7 to check your answers.

Draw Fischer projections of the four stereoisomeric 3-amino-2-butanols, and label each erythro or threo as appropriate.

One other stereoisomer of 3-amino-2-butanol is a crystalline solid. Which one?

One of the stereoisomers of 1,3-dimethylcyclohexane is a meso form. Which one?

Using R and S descriptors, write all the possible combinations for a molecule with three chirality centers.

There are two other stereoisomeric tartaric acids. Write their Fischer projections, and specify the configuration at their chirality centers.

Could the unusual, optically inactive form of tartaric acid studied by Pasteur have been meso-tartaric acid?

In the resolution of 1-phenylethylamine using (S)-(?)-malic acid, the compound obtained by recrystallization of the mixture of diastereomeric salts is (R)-1-phenylethylammonium (S)-malate. The other component of the mixture is more soluble and remains in solution. What is the configuration of the more soluble salt?

When applying Cahn–Ingold–Prelog R,S stereochemical notation to phosphines, the unshared electron pair of phosphorus is taken to be the lowest ranked substituent. Use this information to verify that (+)-benzylmethylphenylphosphine (shown above) has the S configuration.

Including stereoisomers, write structural formulas for all of the compounds that are trichloro derivatives of (a) cyclobutane (b) cyclopentane Which are chiral? Which are achiral?

(?)-Menthol is the most stable stereoisomer of 2-isopropyl-5-methylcyclohexanol and has the R configuration at the hydroxyl-substituted carbon. (a) Draw the preferred conformation of (?)-menthol. (b) (+)-Isomenthol has the same constitution as (?)-menthol. The configurations at C-1 and C-2 of (+)-isomenthol are the opposite of the corresponding chirality centers of (?)-menthol. Write the preferred conformation of (+)-isomenthol.

(a) An aqueous solution containing 10 g of optically pure fructose was diluted to 500 mL with water and placed in a polarimeter tube 20 cm long. The measured rotation was ?5.20°. Calculate the specific rotation of fructose. (b) If this solution were mixed with 500 mL of a solution containing 5 g of racemic fructose, what would be the specific rotation of the resulting fructose mixture? What would be its optical purity?