Solved: The active compound in Pepto-Bismol contains C, H, O, and Bi. (a) When 0.22105 g

What two factors cause water to be polar?

What types of substances are most likely to be soluble in water?

What must be present in an aqueous solution for it to conduct an electric current? What general classes of compounds form solutions that conduct?

What occurs on the molecular level when an ionic compound dissolves in water?

Which of the following scenes best represents how the ions occur in an aqueous solution of: (a) CaCl2; (b) Li2SO4; (c) NH4Br?

Which of the following scenes best represents a volume from a solution of magnesium nitrate?

Why are some ionic compounds soluble in water and others are not?

Why are some covalent compounds soluble in water and others are not?

Some covalent compounds dissociate into ions when they dissolve in water. What atom do these compounds have in their structures? What type of aqueous solution do they form? Name three examples of such an aqueous solution.

State whether each of the following substances is likely to be very soluble in water. Explain. (a) Benzene, C6H6 (b) Sodium hydroxide (c) Ethanol, CH3CH2OH (d) Potassium acetate

State whether each of the following substances is likely to be very soluble in water. Explain. A B C = magnesium ion = nitrate ion A B C + + + + + 2+ 2+ 2+ 2+ 2 2 2 2 + + + + + + + + (a) Lithium nitrate (b) Glycine, H2NCH2COOH (c) Pentane (d) Ethylene glycol, HOCH2CH2OH

State whether an aqueous solution of each of the following substances conducts an electric current. Explain your reasoning. (a) Cesium bromide (b) Hydrogen iodide

State whether an aqueous solution of each of the following substances conducts an electric current. Explain your reasoning. (a) Potassium sulfate (b) Sucrose, C12H22O11

How many total moles of ions are released when each of the following samples dissolves completely in water? (a) 0.32 mol of NH4Cl (b) 25.4 g of Ba(OH)2_8H2O (c) 3.55_1019 formula units of LiCl

How many total moles of ions are released when each of the following samples dissolves completely in water? (a) 0.805 mol of Rb2SO4 (b) 3.85_10_3 g of Ca(NO3)2 (c) 4.03_1019 formula units of Sr(HCO3)2

How many total moles of ions are released when each of the following samples dissolves completely in water? (a) 0.75 mol of K3PO4 (b) 6.88_10_3 g of NiBr2_3H2O (c) 2.23_1022 formula units of FeCl3

How many total moles of ions are released when each of the following samples dissolves completely in water? (a) 0.734 mol of Na2HPO4 (b) 3.86 g of CuSO4_5H2O (c) 8.66_1020 formula units of NiCl2

How many moles and numbers of ions of each type are present in the following aqueous solutions? (a) 130. mL of 0.45 M aluminum chloride (b) 9.80 mL of a solution containing 2.59 g lithium sulfate/L (c) 245 mL of a solution containing 3.68_1022 formula units of potassium bromide per liter

How many moles and numbers of ions of each type are present in the following aqueous solutions? (a) 88 mL of 1.75 M magnesium chloride (b) 321 mL of a solution containing 0.22 g aluminum sulfate/L (c) 1.65 L of a solution containing 8.83_1021 formula units of cesium nitrate per liter

How many moles of H_ ions are present in the following aqueous solutions? (a) 1.40 L of 0.25 M perchloric acid (b) 6.8 mL of 0.92 M nitric acid (c) 2.6 L of 0.085 M hydrochloric acid

How many moles of H_ ions are present in the following aqueous solutions? (a) 1.4 mL of 0.75 M hydrobromic acid (b) 2.47 mL of 1.98 M hydriodic acid (c) 395 mL of 0.270 M nitric acid

To study a marine organism, a biologist prepares a 1.00-kg sample to simulate the ion concentrations in seawater. She mixes 26.5 g of NaCl, 2.40 g of MgCl2, 3.35 g of MgSO4, 1.20 g of CaCl2, 1.05 g of KCl, 0.315 g of NaHCO3, and 0.098 g of NaBr in distilled water. (a) If the density of the solution is 1.025 g/cm3, what is the molarity of each ion? (b) What is the total molarity of alkali metal ions? (c) What is the total molarity of alkaline earth metal ions? (d) What is the total molarity of anions?

Water softeners remove metal ions such as Ca2_ and Fe3_ by replacing them with enough Na_ ions to maintain the same number of positive charges in the solution. If 1.0_103 L of hard water is 0.015 M Ca2_ and 0.0010 M Fe3_, how many moles of Na_ are needed to replace these ions?

Which ions do not appear in a net ionic equation? Why?

Write two sets of equations (both molecular and total ionic) with different reactants that have the same net ionic equation as the following equation: (Sample Problems 4.2 and 4.3)

Why do some pairs of ions precipitate and others do not?

Use Table 4.1 to determine which of the following combinations leads to a precipitation reaction. How can you identify the spectator ions in the reaction? (a) Calcium nitrate(aq) _ sodium chloride(aq) (b) Potassium chloride(aq) _ lead(II) nitrate(aq)

The beakers represent the aqueous reaction of AgNO3 and NaCl. Silver ions are gray. What colors are used to represent NO3 _, Na_, and Cl_? Write molecular, total ionic, and net ionic equations for the reaction.

Complete the following precipitation reactions with balanced molecular, total ionic, and net ionic equations: (a) Hg2(NO3)2(aq) _ KI(aq) (b) FeSO4(aq) _ Sr(OH)2(aq)

Complete the following precipitation reactions with balanced molecular, total ionic, and net ionic equations: (a) CaCl2(aq) _ Cs3PO4(aq) (b) Na2S(aq) _ ZnSO4(aq)

When each of the following pairs of aqueous solutions is mixed, does a precipitation reaction occur? If so, write balanced molecular, total ionic, and net ionic equations: (a) Sodium nitrate _ copper(II) sulfate (b) Ammonium bromide _ silver nitrate

When each of the following pairs of aqueous solutions is mixed, does a precipitation reaction occur? If so, write balanced molecular, total ionic, and net ionic equations: (a) Potassium carbonate _ barium hydroxide (b) Aluminum nitrate _ sodium phosphate

When each of the following pairs of aqueous solutions is mixed, does a precipitation reaction occur? If so, write balanced molecular, total ionic, and net ionic equations. + Ba(NO3)2(aq) _ Na2CO3(aq)BaCO3(s) _ 2NaNO3(aq) (a) Potassium chloride _ iron(III) nitrate (b) Ammonium sulfate _ barium chloride

When each of the following pairs of aqueous solutions is mixed, does a precipitation reaction occur? If so, write balanced molecular, total ionic, and net ionic equations: (a) Sodium sulfide _ nickel(II) sulfate (b) Lead(II) nitrate _ potassium bromide

If 38.5 mL of lead(II) nitrate solution reacts completely with excess sodium iodide solution to yield 0.628 g of precipitate, what is the molarity of lead(II) ion in the original solution?

If 25.0 mL of silver nitrate solution reacts with excess potassium chloride solution to yield 0.842 g of precipitate, what is the molarity of silver ion in the original solution?

With ions shown as spheres and solvent molecules omitted for clarity, the circle (right) illustrates the solid formed when a solution containing K_, Mg2_, Ag_, or Pb2_ (blue) is mixed with one containing ClO4 _, NO3 _, or SO4 2_ (yellow). (a) Identify the solid. (b) Write a balanced net ionic equation for the reaction. (c) If each sphere represents 5.0_10_4 mol of ion, what mass of product forms?

The precipitation reaction between 25.0 mL of a solution containing a cation (purple) and 35.0 mL of a solution containing an anion (green) is depicted below (with ions shown as spheres and solvent molecules omitted for clarity). (a) Given the following choices of reactants, write balanced total ionic and net ionic equations that best represent the reaction: (1) KNO3(aq) _ CuCl2(aq) (2) NaClO4(aq) _ CaCl2(aq) (3) Li2SO4(aq) _AgNO3(aq) (4) NH4Br(aq) _ Pb(CH3COO)2(aq) (b) If each sphere represents 2.5_10_3 mol of ion, find the total number of ions present. (c) What is the mass of solid formed?

The mass percent of Cl_ in a seawater sample is determined by titrating 25.00 mL of seawater with AgNO3 solution, causing a precipitation reaction. An indicator is used to detect the end point, which occurs when free Ag_ ion is present in solution after all the Cl_ has reacted. If 53.63 mL of 0.2970 MAgNO3 is required to reach the end point, what is the mass percent of Cl_ in the seawater (d of seawater _ 1.024 g/mL)?

Aluminum sulfate, known as cake alum, has a wide range of uses, from dyeing leather and cloth to purifying sewage. In aqueous solution, it reacts with base to form a white precipitate. (a) Write balanced total and net ionic equations for its reaction with aqueous NaOH. (b) What mass of precipitate forms when 185.5 mL of 0.533 M NaOH is added to 627 mL of a solution that contains 15.8 g of aluminum sulfate per liter?

Is the total ionic equation the same as the net ionic equation when Sr(OH)2(aq) and H2SO4(aq) react? Explain.

State a general equation for a neutralization reaction.

(a) Name three common strong acids. (b) Name three common strong bases. (c) What is a characteristic behavior of a strong acid or a strong base?

(a) Name three common weak acids. (b) Name one common weak base. (c) What is the major difference between a weak acid and a strong acid or between a weak base and a strong base, and what experiment would you perform to observe it?

Do either of the following reactions go to completion? If so, what factor(s) cause(s) each to do so? (a) MgSO3(s) _ 2HCl(aq) MgCl2(aq) _ SO2(g) _ H2O(l) (b) 3Ba(OH)2(aq) _ 2H3PO4(aq) Ba3(PO4)2(s) _ 6H2O(l)

The net ionic equation for the aqueous neutralization reaction between acetic acid and sodium hydroxide is different from that for the reaction between hydrochloric acid and sodium hydroxide. Explain by writing balanced net ionic equations.

Complete the following acid-base reactions with balanced molecular, total ionic, and net ionic equations: (a) Potassium hydroxide(aq) _ hydrobromic acid(aq) (b) Ammonia(aq) _ hydrochloric acid(aq)

Complete the following acid-base reactions with balanced molecular, total ionic, and net ionic equations: (a) Cesium hydroxide(aq) _ nitric acid(aq) (b) Calcium hydroxide(aq) _ acetic acid(aq)

Limestone (calcium carbonate) is insoluble in water but dissolves when a hydrochloric acid solution is added. Write balanced total ionic and net ionic equations, showing hydrochloric acid as it actually exists in water and the reaction as a protontransfer process.

Zinc hydroxide is insoluble in water but dissolves when a nitric acid solution is added. Why? Write balanced total ionic and net ionic equations, showing nitric acid as it actually exists in water and the reaction as a proton-transfer process.

If 25.98 mL of a standard 0.1180 M KOH solution reacts with 52.50 mL of CH3COOH solution, what is the molarity of the acid solution?

If 26.25 mL of a standard 0.1850 M NaOH solution is required to neutralize 25.00 mL of H2SO4, what is the molarity of the acid solution?

An auto mechanic spills 88 mL of 2.6 M H2SO4 solution from a rebuilt auto battery. How many milliliters of 1.6 M NaHCO3 must be poured on the spill to react completely with the sulfuric acid?

Sodium hydroxide is used extensively in acid-base titrations because it is a strong, inexpensive base. A sodium hydroxide solution was standardized by titrating 25.00 mL of 0.1528 M standard hydrochloric acid. The initial buret reading of the sodium hydroxide was 2.24 mL, and the final reading was 39.21 mL. What was the molarity of the base solution?

An unknown amount of acid can often be determined by adding an excess of base and then back-titrating the excess. A 0.3471-g sample of a mixture of oxalic acid, which has two ionizable protons, and benzoic acid, which has one, is treated with 100.0 mL of 0.1000 M NaOH. The excess NaOH is titrated with 20.00 mL of 0.2000 M HCl. Find the mass % of benzoic acid.

One of the first steps in the enrichment of uranium for use in nuclear power plants involves a displacement reaction between UO2 and aqueous HF: How many liters of 2.40 M HF will react with 2.15 kg of UO2?

A mixture of bases can sometimes be the active ingredient in antacid tablets. If 0.4826 g of a mixture of Al(OH)3 and Mg(OH)2 is neutralized with 17.30 mL of 1.000 M HNO3, what is the mass % of Al(OH)3 in the mixture? (Sample Problems 4.7 to 4.11)

Describe how to determine the oxidation number of sulfur in (a) H2S and (b) SO3 2_.

Is the following a redox reaction? Explain.

Explain why an oxidizing agent undergoes reduction.

Why must every redox reaction involve an oxidizing agent and a reducing agent?

In which of the following equations does sulfuric acid act as an oxidizing agent? In which does it act as an acid? Explain. (a) 4H_(aq) _ SO4 2_(aq) _ 2NaI(s) 2Na_(aq) _ I2(s) _ SO2(g) _ 2H2O(l) (b) BaF2(s) _ 2H_(aq) _ SO4 2_(aq) 2HF(aq) _ BaSO4(s)

Identify the oxidizing agent and the reducing agent in the following reaction, and explain your answer:

Give the oxidation number of carbon in the following: (a) CF2Cl2 (b) Na2C2O4 (c) HCO3 _ (d) C2H6

Give the oxidation number of bromine in the following: (a) KBr (b) BrF3 (c) HBrO3 (d) CBr4

Give the oxidation number of nitrogen in the following: (a) NH2OH (b) N2F4 (c) NH4 _ (d) HNO2

Give the oxidation number of sulfur in the following: (a) SOCl2 (b) H2S2 (c) H2SO3 (d) Na2S

Give the oxidation number of arsenic in the following: (a) AsH3 (b) H2AsO4 _ (c) AsCl3

Give the oxidation number of phosphorus in the following: (a) H2P2O7 2_ (b) PH4 _ (c) PCl5

Give the oxidation number of manganese in the following: (a) MnO4 2_ (b) Mn2O3 (c) KMnO4

Give the oxidation number of chromium in the following: (a) CrO3 (b) Cr2O7 2_ (c) Cr2(SO4)3

Identify the oxidizing and reducing agents in the following: (a) 5H2C2O4(aq) _ 2MnO4 _(aq) _ 6H_(aq) 2Mn2_(aq) _ 10CO2(g) _ 8H2O(l) (b) 3Cu(s) _ 8H_(aq) _ 2NO3 _(aq) 3Cu2_(aq) _ 2NO(g) _ 4H2O(l)

Identify the oxidizing and reducing agents in the following: (a) Sn(s) _ 2H_(aq) Sn2_(aq) _ H2(g) (b) 2H_(aq) _ H2O2(aq) _ 2Fe2_(aq) 2Fe3_(aq) _ 2H2O(l)

Identify the oxidizing and reducing agents in the following: (a) 8H_(aq) _ 6Cl_(aq) _ Sn(s) _ 4NO3 _(aq) SnCl6 2_(aq) _ 4NO2(g) _ 4H2O(l) (b) 2MnO4 _(aq) _ 10Cl_(aq) _ 16H_(aq) 5Cl2(g) _ 2Mn2_(aq) _ 8H2O(l)

Identify the oxidizing and reducing agents in the following: (a) 8H_(aq) _ Cr2O7 2_(aq) _ 3SO3 2_(aq) 2Cr3_(aq) _ 3SO4 2_(aq) _ 4H2O(l) (b) NO3 _(aq) _ 4Zn(s) _ 7OH_(aq) _ 6H2O(l) 4Zn(OH)4 2_(aq) _ NH3(aq)

Discuss each conclusion from a study of redox reactions: (a) The sulfide ion functions only as a reducing agent. (b) The sulfate ion functions only as an oxidizing agent. (c) Sulfur dioxide functions as an oxidizing or a reducing agent.

Discuss each conclusion from a study of redox reactions: (a) The nitride ion functions only as a reducing agent. (b) The nitrate ion functions only as an oxidizing agent. (c) The nitrite ion functions as an oxidizing or a reducing agent.

Use the oxidation number method to balance the following equations by placing coefficients in the blanks. Identify the reducing and oxidizing agents: (a) __HNO3(aq) _ __K2CrO4(aq) _ __Fe(NO3)2(aq) __KNO3(aq) _ __Fe(NO3)3(aq) _ __Cr(NO3)3(aq) _ __H2O(l) (b) __HNO3(aq) _ __C2H6O(l) _ __K2Cr2O7(aq) __KNO3(aq) _ __C2H4O(l) _ __H2O(l) _ __Cr(NO3)3(aq) (c) __HCl(aq) _ __NH4Cl(aq) _ __K2Cr2O7(aq) __KCl(aq) _ __CrCl3(aq) _ __N2(g) _ __H2O(l) (d) __KClO3(aq) _ __HBr(aq) __Br2(l) _ __H2O(l) _ __KCl(aq)

Use the oxidation number method to balance the following equations by placing coefficients in the blanks. Identify the reducing and oxidizing agents: (a) __HCl(aq) _ __FeCl2(aq) _ __H2O2(aq) __FeCl3(aq) _ __H2O(l) (b) __I2(s) _ __Na2S2O3(aq) __Na2S4O6(aq) _ __NaI(aq) (c) __HNO3(aq) _ __KI(aq) __NO(g) _ __I2(s) _ __H2O(l) _ __KNO3(aq) (d) __PbO(s) _ __NH3(aq) __N2(g) _ __H2O(l) _ __Pb(s)

The active agent in many hair bleaches is hydrogen peroxide. The amount of H2O2 in 14.8 g of hair bleach was determined by titration with a standard potassium permanganate solution: (a) How many moles of MnO4 _ were required for the titration if 43.2 mL of 0.105 M KMnO4 was needed to reach the end point? (b) How many moles of H2O2 were present in the 14.8-g sample of bleach? 5O2(g) _ 2Mn2_(aq) _ 8H2O(l) 2MnO4 _(aq) _ 5H2O2(aq) _ 6H_(aq) (c) How many grams of H2O2 were in the sample? (d) What is the mass percent of H2O2 in the sample? (e) What is the reducing agent in the redox reaction?

A persons blood alcohol (C2H5OH) level can be determined by titrating a sample of blood plasma with a potassium dichromate solution. The balanced equation is If 35.46 mL of 0.05961 M Cr2O7 2_ is required to titrate 28.00 g of plasma, what is the mass percent of alcohol in the blood? (Sample Problem 4.12)

Which type of redox reaction leads to the following? (a) An increase in the number of substances (b) A decrease in the number of substances (c) No change in the number of substances

Why do decomposition reactions typically have compounds as reactants, whereas combination and displacement reactions have one or more elements?

Which of the three types of reactions discussed in Section 4.6 commonly produce one or more compounds?

Are all combustion reactions redox reactions? Explain.

Give one example of a combination reaction that is a redox reaction and another that is not a redox reaction.

Balance each of the following redox reactions and classify it as a combination, decomposition, or displacement reaction: (a) Ca(s) _ H2O(l) Ca(OH)2(aq) _ H2(g) (b) NaNO3(s) NaNO2(s) _ O2(g) (c) C2H2(g) _ H2(g) C2H6(g)

Balance each of the following redox reactions and classify it as a combination, decomposition, or displacement reaction: (a) HI(g) H2(g) _ I2(g) (b) Zn(s) _AgNO3(aq) Zn(NO3)2(aq) _Ag(s) (c) NO(g) _ O2(g) N2O4(l)

Balance each of the following redox reactions and classify it as a combination, decomposition, or displacement reaction: (a) Sb(s) _ Cl2(g) SbCl3(s) (b) AsH3(g) As(s) _ H2(g) (c) Zn(s) _ Fe(NO3)2(aq) Zn(NO3)2(aq) _ Fe(s)

Balance each of the following redox reactions and classify it as a combination, decomposition, or displacement reaction: (a) Mg(s) _ H2O(g) Mg(OH)2(s) _ H2(g) (b) Cr(NO3)3(aq) _Al(s) Al(NO3)3(aq) _ Cr(s) (c) PF3(g) _ F2(g) PF5(g)

Predict the product(s) and write a balanced equation for each of the following redox reactions: (a) Sr(s) _ Br2(l) (b) Ag2O(s) (c) Mn(s) _ Cu(NO3)2(aq)

Predict the product(s) and write a balanced equation for each of the following redox reactions: (a) Mg(s) _ HCl(aq) (b) LiCl(l) (c) SnCl2(aq) _ Co(s)

Predict the product(s) and write a balanced equation for each of the following redox reactions: (a) N2(g) _ H2(g) (b) NaClO3(s) (c) Ba(s) _ H2O(l)

Predict the product(s) and write a balanced equation for each of the following redox reactions: (a) Fe(s) _ HClO4(aq) (b) S8(s) _ O2(g) (c) BaCl2(l)

Predict the product(s) and write a balanced equation for each of the following redox reactions: (a) Cesium _ iodine (b) Aluminum _ aqueous manganese(II) sulfate (c) Sulfur dioxide _ oxygen (d) Butane and oxygen (e) Write a balanced net ionic equation for (b).

Predict the product(s) and write a balanced equation for each of the following redox reactions: (a) Pentane (C5H12) _ oxygen (b) Phosphorus trichloride _ chlorine (c) Zinc _ hydrobromic acid (d) Aqueous potassium iodide _ bromine (e) Write a balanced net ionic equation for (d).

How many grams of O2 can be prepared from the thermal decomposition of 4.27 kg of HgO? Name and calculate the mass (in kg) of the other product.

How many grams of chlorine gas can be produced from the electrolytic decomposition of 874 g of calcium chloride? Name and calculate the mass (in g) of the other product.

In a combination reaction, 1.62 g of lithium is mixed with 6.50 g of oxygen. (a) Which reactant is present in excess? (b) How many moles of product are formed? (c) After reaction, how many grams of each reactant and product are present?

In a combination reaction, 2.22 g of magnesium is heated with 3.75 g of nitrogen. (a) Which reactant is present in excess? (b) How many moles of product are formed? (c) After reaction, how many grams of each reactant and product are present?

A mixture of KClO3 and KCl with a mass of 0.950 g was heated to produce O2. After heating, the mass of residue was 0.700 g. Assuming all the KClO3 decomposed to KCl and O2, calculate the mass percent of KClO3 in the original mixture.

A mixture of CaCO3 and CaO weighing 0.693 g was heated to produce gaseous CO2. After heating, the remaining solid weighed 0.508 g. Assuming all the CaCO3 broke down to CaO and CO2, calculate the mass percent of CaCO3 in the original mixture.

Before arc welding was developed, a displacement reaction involving aluminum and iron(III) oxide was commonly used to produce molten iron (the thermite process). This reaction was used, for example, to connect sections of iron railroad track. Calculate the mass of molten iron produced when 1.50 kg of aluminum reacts with 25.0 mol of iron(III) oxide.

Iron reacts rapidly with chlorine gas to form a reddish brown, ionic compound (A), which contains iron in the higher of its two common oxidation states. Strong heating decomposes electricity compound A to compound B, another ionic compound, which contains iron in the lower of its two oxidation states. When compound A is formed by the reaction of 50.6 g of Fe and 83.8 g of Cl2 and then heated, how much compound B forms?

Why is the equilibrium state called dynamic?

In a decomposition reaction involving a gaseous product, what must be done for the reaction to reach equilibrium?

Describe what happens on the molecular level when acetic acid dissolves in water.

When either a mixture of NO and Br2 or pure nitrosyl bromide (NOBr) is placed in a reaction vessel, the product mixture contains NO, Br2, and NOBr. Explain.

Ammonia is produced by the millions of tons annually for use as a fertilizer. It is commonly made from N2 and H2 by the Haber process. Because the reaction reaches equilibrium before going completely to product, the stoichiometric amount of ammonia is not obtained. At a particular temperature and pressure, 10.0 g of H2 reacts with 20.0 g of N2 to form ammonia. When equilibrium is reached, 15.0 g of NH3 has formed. (a) Calculate the percent yield. (b) How many moles of N2 and H2 are present at equilibrium?

Nutritional biochemists have known for decades that acidic foods cooked in cast-iron cookware can supply significant amounts of dietary iron (ferrous ion). (a) Write a balanced net ionic equation, with oxidation numbers, that supports this fact. (b) Measurements show an increase from 3.3 mg of iron to 49 mg of iron per -cup (125-g) serving during the slow preparation of tomato sauce in a cast-iron pot. How many ferrous ions are present in a 26-oz (737-g) jar of the tomato sauce?

Limestone (CaCO3) is used to remove acidic pollutants from smokestack flue gases. It is heated to form lime (CaO), which reacts with sulfur dioxide to form calcium sulfite. Assuming a 70.% yield in the overall reaction, what mass of limestone is required to remove all the sulfur dioxide formed by the combustion of 8.5_104 kg of coal that is 0.33 mass % sulfur?

The brewing industry uses yeast microorganisms to convert glucose to ethanol for wine and beer. The baking industry uses the carbon dioxide produced to make bread rise: How many grams of ethanol can be produced from 100. g of glucose? What volume of CO2 is produced? (Assume 1 mol of gas occupies 22.4 L at the conditions used.)

A chemical engineer determines the mass percent of iron in an ore sample by converting the Fe to Fe2_ in acid and then titrating the Fe2_ with MnO4 _. A 1.1081-g sample was dissolved in acid and then titrated with 39.32 mL of 0.03190 M KMnO4. The balanced equation is Calculate the mass percent of iron in the ore.

Mixtures of CaCl2 and NaCl are used to melt ice on roads. Adissolved 1.9348-g sample of such a mixture was analyzed by using excess Na2C2O4 to precipitate the Ca2_ as CaC2O4. The CaC2O4 was dissolved in sulfuric acid, and the resulting H2C2O4 was titrated with 37.68 mL of 0.1019 M KMnO4 solution. (a) Write the balanced net ionic equation for the precipitation reaction. (b) Write the balanced net ionic equation for the titration reaction. (See Sample Problem 4.11.) (c) What is the oxidizing agent? (d) What is the reducing agent? (e) Calculate the mass percent of CaCl2 in the original sample.

You are given solutions of HCl and NaOH and must determine their concentrations. You use 27.5 mL of NaOH to titrate 100. mL of HCl and 18.4 mL of NaOH to titrate 50.0 mL of 0.0782 M H2SO4. Find the unknown concentrations.

The flask (right) represents the products of the titration of 25 mL of sulfuric acid with 25 mL of sodium hydroxide. (a) Write balanced molecular, total ionic, and net ionic equations for the reaction. (b) If each orange sphere represents 0.010 mol of sulfate ion, how many moles of acid and of base reacted? (c) What are the molarities of the acid and the base?

To find the mass percent of dolomite [CaMg(CO3)2 in a soil sample, a geochemist titrates 13.86 g of soil with 33.56 mL of 0.2516 M HCl. What is the mass percent of dolomite in the soil?

On a lab exam, you have to find the concentrations of the monoprotic (one proton per molecule) acids HA and HB. You are given 43.5 mL of HA solution in one flask. A second flask contains 37.2 mL of HA, and you add enough HB solution to it to reach a final volume of 50.0 mL. You titrate the first HA solution with 87.3 mL of 0.0906 M NaOH and the mixture of HA and HB in the second flask with 96.4 mL of the NaOH solution. Calculate the molarity of the HA and HB solutions.

Nitric acid, a major industrial and laboratory acid, is produced commercially by the multistep Ostwald process, which begins with the oxidation of ammonia: Step 1. 4NH3(g) _ 5O2(g) 4NO(g) _ 6H2O(l) Step 2. 2NO(g) _ O2(g) 2NO2(g) Step 3. 3NO2(g) _ H2O(l) 2HNO3(l) _ NO(g) (a) What are the oxidizing and reducing agents in each step? (b) Assuming 100% yield in each step, what mass (in kg) of ammonia must be used to produce 3.0_104 kg of HNO3?

For the following aqueous reactions, complete and balance the molecular equation and write a net ionic equation: (a) Manganese(II) sulfide _ hydrobromic acid (b) Potassium carbonate _ strontium nitrate (c) Potassium nitrite _ hydrochloric acid (d) Calcium hydroxide _ nitric acid (e) Barium acetate _ iron(II) sulfate (f) Zinc carbonate _ sulfuric acid (g) Copper(II) nitrate _ hydrosulfuric acid (h) Magnesium hydroxide _ chloric acid (i) Potassium chloride _ ammonium phosphate ( j) Barium hydroxide _ hydrocyanic acid

There are various methods for finding the composition of an alloy (a metal-like mixture). Show that calculating the mass % of Mg in a magnesium-aluminum alloy (d _ 2.40 g/cm3) gives the same answer (within rounding) using each of these methods: (a) a 0.263-g sample of alloy (d of Mg _ 1.74 g/cm3; d of Al _ 2.70 g/cm3); (b) an identical sample reacting with excess aqueous HCl forms 1.38_10_2 mol of H2; (c) an identical sample reacting with excess O2 forms 0.483 g of oxide.

Use the oxidation number method to balance the following equations by placing coefficients in the blanks. Identify the reducing and oxidizing agents: (a) __KOH(aq) _ __H2O2(aq) _ __Cr(OH)3(s) __K2CrO4(aq) _ __H2O(l) (b) __MnO4 _(aq) _ __ClO2 _(aq) _ __H2O(l) __MnO2(s) _ __ClO4 _(aq) _ __OH_(aq) (c) __KMnO4(aq) _ __Na2SO3(aq) _ __H2O(l) __MnO2(s) _ __Na2SO4(aq) _ __KOH(aq) (d) __CrO4 2_(aq) _ __HSnO2 _(aq) _ __H2O(l) __CrO2 _(aq) _ __HSnO3 _(aq) _ __OH_(aq) (e) __KMnO4(aq) _ __NaNO2(aq) _ __H2O(l) __MnO2(s) _ __NaNO3(aq) _ __KOH(aq) (f ) __I_(aq) _ __O2(g) _ __H2O(l) __I2(s) _ __OH_(aq)

In 1995, Mario Molina, Paul Crutzen, and F. Sherwood Rowland shared the Nobel Prize in chemistry for their work on atmospheric chemistry. One of several reaction sequences proposed for the role of chlorine in the decomposition of stratospheric ozone (well see another sequence in Chapter 16) is (1) Cl(g) _ O3(g) ClO(g) _ O2(g) (2) ClO(g) _ ClO(g) Cl2O2(g) (3) Cl2O2(g) 2Cl(g) _ O2(g) Over the tropics, O atoms are more common in the stratosphere: (4) ClO(g) _ O(g) Cl(g) _ O2(g) (a) Which, if any, of these are oxidation-reduction reactions? (b) Write an overall equation combining reactions 13.

Sodium peroxide (Na2O2) is often used in self-contained breathing devices, such as those used in fire emergencies, because it reacts with exhaled CO2 to form Na2CO3 and O2. How many liters of respired air can react with 80.0 g of Na2O2 if each liter of respired air contains 0.0720 g of CO2?

A student forgets to weigh a mixture of sodium bromide dihydrate and magnesium bromide hexahydrate. Upon strong heating, the sample loses 252.1 mg of water. The mixture of anhydrous salts reacts with excess AgNO3 solution to form 6.00_10_3 mol of solid AgBr. Find the mass % of each compound in the original mixture.

Magnesium is used in lightweight alloys for airplane bodies and other structures. The metal is obtained from seawater in a process that includes precipitation, neutralization, evaporation, and electrolysis. How many kilograms of magnesium can be obtained from 1.00 km3 of seawater if the initial Mg2_ concentration is 0.13% by mass (d of seawater _ 1.04 g/mL)?

A typical formulation for window glass is 75% SiO2, 15% Na2O, and 10.% CaO by mass. What masses of sand (SiO2), sodium carbonate, and calcium carbonate must be combined to produce 1.00 kg of glass after carbon dioxide is driven off by thermal decomposition of the carbonates?

Physicians who specialize in sports medicine routinely treat athletes and dancers. Ethyl chloride, a local anesthetic commonly used for simple injuries, is the product of the combination of ethylene with hydrogen chloride: If 0.100 kg of C2H4 and 0.100 kg of HCl react: (a) How many molecules of gas (reactants plus products) are present when the reaction is complete? (b) How many moles of gas are present when half the product forms?

The salinity of a solution is defined as the grams of total salts per kilogram of solution. An agricultural chemist uses a solution whose salinity is 35.0 g/kg to test the effect of irrigating farmland with high-salinity river water. The two solutes are NaCl and MgSO4, and there are twice as many moles of NaCl as MgSO4. What masses of NaCl and MgSO4 are contained in 1.00 kg of the solution?

Thyroxine (C15H11I4NO4) is a hormone synthesized by the thyroid gland and used to control many metabolic functions in the body. A physiologist determines the mass percent of thyroxine in a thyroid extract by igniting 0.4332 g of extract with sodium carbonate, which converts the iodine to iodide. The iodide is dissolved in water, and bromine and hydrochloric acid are added, which convert the iodide to iodate. (a) How many moles of iodate form per mole of thyroxine? (b) Excess bromine is boiled off and more iodide is added, which reacts as shown in the following unbalanced equation: How many moles of iodine are produced per mole of thyroxine? (Hint: Be sure to balance the charges as well as the atoms.) What are the oxidizing and reducing agents in the reaction? (c) The iodine reacts completely with 17.23 mL of 0.1000 M thiosulfate as shown in the following unbalanced equation: What is the mass percent of thyroxine in the thyroid extract?

Over time, as their free fatty acid (FFA) content increases, edible fats and oils become rancid. To measure rancidity, the fat or oil is dissolved in ethanol, and any FFApresent is titrated with KOH dissolved in ethanol. In a series of tests on olive oil, a stock solution of 0.050 M ethanolic KOH was prepared at 25_C, stored at 0_C, and then placed in a 100-mL buret to titrate any oleic acid [CH3(CH2)7CH CH(CH2)7COOH] present in the oil. Each of four 10.00-g samples of oil took several minutes to titrate: the first required 19.60 mL, the second 19.80 mL, and the third and fourth 20.00 mL of the ethanolic KOH. (a) What is the apparent acidity of each sample, in terms of mass % of oleic acid? (Note: As the ethanolic KOH warms in the buret, its volume increases by a factor of 0.00104/_C.) (b) Is the variation in acidity a random or systematic error? Explain. (c) What is the actual acidity? How would you demonstrate this?

Carbon dioxide is removed from the atmosphere of space capsules by reaction with a solid metal hydroxide. The products are water and the metal carbonate. (a) Calculate the mass of CO2 that can be removed by reaction with 3.50 kg of lithium hydroxide. (b) How many grams of CO2 can be removed by 1.00 g of each of the following: lithium hydroxide, magnesium hydroxide, and aluminum hydroxide?

A chemist mixes solid AgCl, CuCl2, and MgCl2 in enough water to give a final volume of 50.0 mL. N I2(aq) _ S2O3 2_(aq)I_(aq) _ S4O6 2_(aq) IO3 _(aq) _ H_(aq) _ I_(aq)I2(aq) _ H2O(l) C2H4(g) _ HCl(g)C2H5Cl(g) (a) With ions shown as spheres and solvent molecules omitted for clarity, which of the following best represents the resulting mixture? (b) If each sphere represents 5.0_10_3 mol of ions, what is the total concentration of dissolved (separated) ions? (c) What is the total mass of solid?

Calcium dihydrogen phosphate, Ca(H2PO4)2, and sodium hydrogen carbonate, NaHCO3, are ingredients of baking powder that react with each other to produce CO2, which causes dough or batter to rise: [unbalanced] If the baking powder contains 31% NaHCO3 and 35% Ca(H2PO4)2 by mass: (a) How many moles of CO2 are produced from 1.00 g of baking powder? (b) If 1 mol of CO2 occupies 37.0 L at 350_F (a typical baking temperature), what volume of CO2 is produced from 1.00 g of baking powder?

In a titration of HNO3, you add a few drops of phenolphthalein indicator to 50.00 mL of acid in a flask. You quickly add 20.00 mL of 0.0502 M NaOH but overshoot the end point, and the solution turns deep pink. Instead of starting over, you add 30.00 mL of the acid, and the solution turns colorless. Then, it takes 3.22 mL of the NaOH to reach the end point. (a) What is the concentration of the HNO3 solution? (b) How many moles of NaOH were in excess after the first addition?

The active compound in Pepto-Bismol contains C, H, O, and Bi. (a) When 0.22105 g of it was burned in excess O2, 0.1422 g of bismuth(III) oxide, 0.1880 g of carbon dioxide, and 0.02750 g of water were formed. What is the empirical formula of this compound? (b) Given a molar mass of 1086 g/mol, determine the molecular formula. (c) Complete and balance the acid-base reaction between bismuth( III) hydroxide and salicylic acid (HC7H5O3), which is used to form this compound. (d) A dose of Pepto-Bismol contains 0.600 mg of the active ingredient. If the yield of the reaction in part (c) is 88.0%, what mass (in mg) of bismuth(III) hydroxide is required to prepare one dose?

Two aqueous solutions contain the ions indicated below. (a) Write balanced molecular, total ionic, and net ionic equations for the reaction that occurs when the solutions are mixed. (b) If each sphere represents 0.050 mol of ion, what mass (in g) of precipitate forms, assuming 100% reaction? (c) What is the concentration of each ion in solution after reaction?

In 1997, at the United Nations Conference on Climate Change, the major industrial nations agreed to expand their research efforts to develop renewable sources of carbon-based fuels. For more than a decade, Brazil has been engaged in a program to replace gasoline with ethanol derived from the root crop manioc (cassava). (a) Write separate balanced equations for the complete combustion of ethanol (C2H5OH) and of gasoline (represented by the formula C8H18). (b) What mass of oxygen is required to burn completely 1.00 L of a mixture that is 90.0% gasoline (d _ 0.742 g/mL) and 10.0% ethanol (d _ 0.789 g/mL) by volume? (c) If 1.00 mol of O2 occupies 22.4 L, what volume of O2 is needed to burn 1.00 L of the mixture? (d) Air is 20.9% O2 by volume. What volume of air is needed to burn 1.00 L of the mixture?

In a car engine, gasoline (represented by C8H18) does not burn completely, and some CO, a toxic pollutant, forms along with CO2 and H2O. If 5.0% of the gasoline forms CO: (a) What is the ratio of CO2 to CO molecules in the exhaust? (b) What is the mass ratio of CO2 to CO? (c) What percentage of the gasoline must form CO for the mass ratio of CO2 to CO to be exactly 1/1?

The amount of ascorbic acid (vitamin C; C6H8O6) in tablets is determined by reaction with bromine and then titration of the hydrobromic acid with standard base: Acertain tablet is advertised as containing 500 mg of vitamin C. One tablet was dissolved in water and reacted with Br2. The solution was then titrated with 43.20 mL of 0.1350 M NaOH. Did the tablet contain the advertised quantity of vitamin C? HBr _ NaOHNaBr _ H2O C6H8O6 _ Br2C6H6O6 _ 2HBr + Na+ CO3 2 Ca2+ Cl = = = = 250. mL 250. mL

In the process of salting-in, protein solubility in a dilute salt solution is increased by adding more salt. Because the protein solubility depends on the total ion concentration as well as the ion charge, salts yielding doubly charged ions are often more effective than those yielding singly charged ions. (a) How many grams of MgCl2 must dissolve to equal the ion concentration of 12.4 g of NaCl? (b) How many grams of CaS must dissolve? (c) Which of the three salt solutions would dissolve the most protein?

In the process of pickling, rust is removed from newly produced steel by washing the steel in hydrochloric acid: (1) 6HCl(aq) _ Fe2O3(s) 2FeCl3(aq) _ 3H2O(l) During the process, some iron is lost as well: (2) 2HCl(aq) _ Fe(s) FeCl2(aq) _ H2(g) (a) Which reaction, if either, is a redox process? (b) If reaction 2 did not occur and all the HCl were used, how many grams of Fe2O3 could be removed and FeCl3 produced in a 2.50_103-L bath of 3.00 M HCl? (c) If reaction 1 did not occur and all the HCl were used, how many grams of Fe could be lost and FeCl2 produced in a 2.50_103-L bath of 3.00 M HCl? (d) If 0.280 g of Fe is lost per gram of Fe2O3 removed, what is the mass ratio of FeCl2 to FeCl3?

At liftoff, a space shuttle uses a solid mixture of ammonium perchlorate and aluminum powder to obtain great thrust from the volume change of solid to gas. In the presence of a catalyst, the mixture forms solid aluminum oxide and aluminum trichloride and gaseous water and nitrogen monoxide. (a) Write a balanced equation for the reaction, and identify the reducing and oxidizing agents. (b) How many total moles of gas (water vapor and nitrogen monoxide) are produced when 50.0 kg of ammonium perchlorate reacts with a stoichiometric amount of Al? (c) What is the volume change from this reaction? (d of NH4ClO4 _ 1.95 g/cc, Al _ 2.70 g/cc, Al2O3 _ 3.97 g/cc, and AlCl3 _ 2.44 g/cc; assume 1 mol of gas occupies 22.4 L.)

A reaction cycle for an element is a series of reactions beginning and ending with that element. In the following copper reaction cycle, copper has either a 0 or a _2 oxidation state. Write balanced molecular and net ionic equations for each step in the cycle. (1) Copper metal reacts with aqueous bromine to produce a green-blue solution. (2) Adding aqueous sodium hydroxide forms a blue precipitate. (3) The precipitate is heated and turns black (water is released). (4) The black solid dissolves in nitric acid to give a blue solution. (5) Adding aqueous sodium phosphate forms a green precipitate. (6) The precipitate forms a blue solution in sulfuric acid. (7) Copper metal is recovered from the blue solution when zinc metal is added.