Calculate the pH of a 2.00 M NH4CN solution.

Problem 178AP A 1.87-g sample of Mg reacts with 80.0 mL of a HCl solution whose pH is ?0.544. What is the pH of the solution after all the Mg has reacted? Assume constant volume.

Problem 2QP identify the acid-base conjugate pairs in each of the following reactions:

Problem 1VC Which weak acid has the largest Ka value? (a) i ________________ (b) ii ________________ (c) iii

Problem 2VC Which weak acid has the highest pH? (a) i ________________ (b) ii ________________ (c) iii

Problem 3QP Classify each of the following species as a Brønsted acid or base, or both:

Problem 3VC For which weak acid solution can we most likely neglect x in the denominator of the equilibrium expression in the determination of pH? (a) i ________________ (b) ii ________________ (c) iii

Problem 1QP For a species to act as a Brønsted base, an atom in the species must possess a lone pair of electrons. Explain why this is so.

Problem 4QP Write the formula for the conjugate acid of each of the following bases:

In the event that we cannot neglect x in the denominator of the equilibrium expression, ____________________ to solve for pH. (a) we cannot use an equilibrium table (b) we must use the quadratic equation (c) it is unnecessary

Problem 5QP Write the formulas of the conjugate bases of the following acids: (formic acid).

Problem 6QP Oxalic acid (H2C2O4) has the following structure: An oxalic acid solution contains the following species in varying concentrations: and H+. (a) Draw Lewis structures of HC2O4, and .(b) Which of the four species can act only as acids, which can act only as bases, and which can act as both acids and bases?

Problem 7QP Write the formula for the conjugate base of each of the following acids:

Problem 8QP List four factors that affect the strength of an acid.

Problem 9QP How does the strength of an oxoacid depend on the electronegativity and oxidation number of the central atom?

Problem 10QP Predict the relative acid strengths of the following compounds: H2O. H2S, and H2Se.

Compare the strengths of the following pairs of acids: \(\text { (a) } \mathrm{H}_{2} \mathrm{SO}_{4} \text { and } \mathrm{H}_{2} \mathrm{SeO}_{4} \text {, (b) } \mathrm{H}_{3} \mathrm{PO}_{4} \text { and } \mathrm{H}_{3} \mathrm{AsO}_{4}\)

Problem 12QP Which of the following is the stronger acid: CH2CICOOH or CHCl2COOH? Explain your choice.

Problem 14QP Write the equilibrium expression for the autoionization of water.

Problem 13QP Consider the following compounds: Experimentally, phenol is found to be a stronger acid than methanol. Explain this difference in terms of the structures of the conjugate bases. (Hint: A more stable conjugate base favors ionization. Only one of the conjugate bases can be stabilized by resonance.)

Problem 15QP Write an equation relating [H+] and [OH?] in solution at 25°C.

The equilibrium constant for the autoionization of water \(\mathrm{H}_{2} \mathrm{O}(l) \rightleftarrows \mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q)\) is \(1.0 \times 10^{-14}\) at \(25^{\circ} \mathrm{C}\) and \(3.8 \times 10^{-14}\) at \(40^{\circ} \mathrm{C}\). Is the forward process endothermic or exothermic?

Problem 17QP Compare the magnitudes of [H+] and [OH-] in aqueous solutions that are acidic, basic, and neutral.

Problem 18QP Calculate the OH concentration in an aqueous solution at 25°C with each of the following OH- concentrations: (a) 1.13 X 10~4 M (b) 4.55 X 1 (Ts M, (c) 7.05 X 10~" XI, (d) 3.13 x 10 2 M.

Problem 19QP Calculate the H3O+ concentration in an aqueous solution at 25°C with each of the following OH- concentrations: (a) 2.50 × 10-2 M. (b) 1.67 X 10-5 M, (c) 8.62 X 10-3 M. (d) 1.75 X 10-12 M.

Problem 21QP The value of Kw at 100°C is 5.13 × 10-13 Calculate the H3O+concentration in each of the aqueous solutions from Problem 16.15 at 100°C.

Problem 20QP The value of Kw at 50°C is 5.48 x 10-14. Calculate the OH- concentration in each of the aqueous solutions from Problem 16.14 at 50°C.

Problem 22QP Define pH. Why do chemists normally choose to discuss the acidity of a solution in terms of pH rather than hydrogen ion concentration [H+]? Define pOH. Write the equation relating pH and pOH.

Problem 23QP The pH of a solution is 6.7. From this statement alone, can you conclude that the solution is acidic? If not, what additional information would you need? Can the pH of a solution be zero or negative? If so, give examples to illustrate these values.

Calculate the concentration of \(\mathrm{H}^{+}\) ions in a 0.62 M NaOH solution.

Problem 25QP Calculate the concentration of OH- ions in a 1.4 × 10-3 MHCl solution.

Problem 26QP Calculate the pH of each of the following solutions:

Problem 27QP Calculate the pH of each of the following solutions:

Problem 28QP Calculate the hydrogen ion concentration in mol/L for each of the following solutions: (a) a solution whose pH is 5.20. (b) a solution whose pH is 16.00. (c) a solution whose hydroxide concentration is 3.7 X 10-9M.

Problem 29QP Calculate the hydrogen ion concentration in mol/L for solutions with the following pH values: (a) 2.42, (b) 11.21, (c) 6.96, (d) 15.00.

Problem 31QP Complete the following table for a solution:

Problem 32QP Calculate the number of moles of KOH in 5.50 mL of a 0.360 M KOH solution. What is the pOH of the solution at 25°C?

Problem 33QP The pOH of a solution is 9.40 at 25°C. Calculate the hydrogen ion concentration of the solution.

Problem 30QP Fill in the word acidic, basic, or neutral for the following solutions: (a) pOH > 7: solution is________________ ________________ (b) pOH = 7; solution is________________ ________________ (c) pOH<7: solution is________________

Problem 34QP A solution is made by dissolving 18.4 g of HCl in enough water to make 662 mL of solution. Calculate the pH of the solution at 25°C.

Problem 35QP How much NaOH (in grams) is needed to prepare 546 mL of solution with a pH of 10.00 at 25°C?

Problem 36QP Which of the following statements are true regarding a 1.0 M solution of a strong acid HA at 25°C? (Choose all that apply.)

Problem 37QP Why are ionizations of strong acids and strong bases generally not treated as equilibria?

Problem 38QP Calculate the pH of an aqueous solution at 25°C that is (a) 0.12 M in HCl. (b) 2.4 M in HNO3. and (c) 3.2 x 10-4 M in HClO4.

Problem 39QP Calculate the pH of an aqueous solution at 25°C that is (a) 1.02 M in HI. (b) 0.035 .Win HClO4, and (c) 1.5 x 10-6M in HCl.

Problem 40QP Calculate the concentration of HBr in a solution at 25°C that has a pH of (a) 0.12, (b) 2.46. and (c) 6.27.

Problem 41QP Calculate the concentration of HNO3 in a solution at 25°C that has a pH of (a) 4.21, (b) 3.55, and (c) 0.98.

Problem 42QP Calculate the pOH and pH of the following aqueous solutions at 25°C: (a) 0.066 MKOH, (b) 5.43 MNaOH. (c) 0.74 ,MBa(OH)2.

Calculate the pOH and pH of the following aqueous solutions at \(25^{\circ} \mathrm{C}\): (a) 1.24 M LiOH, (b) 0.22 M \(\mathrm{Ba}(\mathrm{OH})_{2}\), (c) 0.085 M NaOH.

Problem 44QP An aqueous solution of a strong base has a pH of 9.78 at 25°C. Calculate the concentration of the base if the base is (a) LiOH and (b) Ba(OH)2.

Problem 45QP An aqueous solution of a strong base has a pH o f 11.04 at 25°C. Calculate the concentration of the base if the base is (a) KOH and (b) Ba(OH)2.

Problem 46QP Determine [H+] and pH for a raindrop in which the carbonic acid concentration is 1.8 × 10?5 M. Assume that carbonic acid is the only acid in the raindrop and that the second ionization is negligible.

Problem 47QP A sample of acid rain collected from a pond was shown to have a pH = 4.65. What concentration of HNO3 does this pH correspond to?

Problem 48QP Explain what is meant by the strength of an acid.

Problem 49QP What does the ionization constant tell us about the strength of an acid?

Problem 51QP Why do we normally not quote Ka values for strong acids such as HCl and HNO3?

Problem 50QP List the factors on which the Ka of a weak acid depends.

Problem 52QP Why is it necessary to specify temperature when giving Ka values?

Problem 53QP Which of the following solutions has the highest pH:

Problem 54QP Classify each of the following species as a weak or strong acid:

Problem 55QP Classify each of the following species as a weak or strong base:

Problem 56QP Which of the following statements are true for a 0.10 M solution of a weak acid HA? (Choose all that apply.)

Problem 57QP The Ka, for benzoic acid is 6.5 × 10-5 Calculate the pH of a 0.10 M aqueous solution of benzoic acid at 25°C.

Problem 58QP The Ka for hydrofluoric acid is 7.1 × 10-4. Calculate the pH of a 0.15 M aqueous solution of hydrofluoric acid at 25°C.

Calculate the \(\mathrm{pH}\) of an aqueous solution at \(25^{\circ} \mathrm{C}\) that is \(0.095 M\) in hydrocyanic acid (HCN). ( \(K_{\mathrm{a}}\) for hydrocyanic acid \(=4.9 \times 10^{-10}\).)

Calculate the pH of an aqueous solution at 25°C that is 0.34 M in phenol \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}\right)\). (K\(K_{\mathrm{a}}\) for phenol = \(1.3 \times 10^{-10}\).)

Determine the percent ionization of the following solutions of formic acid at 25°C: (a) 0.016 M, \(\text { (b) } 5.7 \times 10^{-4} \mathrm{M} \text {, (c) } 1.75 \mathrm{M}\).

Problem 62QP Determine the percent ionization of the following solutions of phenol: (a) 0.56 M,(b) 0.25 M, (c)1.8 x 10-6 M.

Problem 64QP Calculate the concentration at which a monoprotic acid with Ka, = 4.5 × 10-5 will be 2.5 percent ionized.

Problem 63QP A 0.015 M solution of a monoprotic acid is 0.92 percent ionized. Calculate the ionization constant for the acid.

Problem 65QP Calculate the Ka of a weak acid if a 0.19 M aqueous solution of the acid has a pH of 4.52 at 25°C.

Problem 66QP The pH of an aqueous acid solution is 6.20 at 25°C. Calculate the Ka for the acid. The initial acid concentration is 0.010 M

Problem 67QP What is the original molarity of a solution of formic acid (HCOOH) whose pH is 3.26 at 25°C? (Ka, for formic acid = 1.7 X 10-4.)

Problem 68QP What is the original molarity of a solution of a weak acid whose Ka, is 3.5 × 10-5 and whose pH is 5.26 at 25°C?

In biological and medical applications, it is often necessary to study the autoionization of water at 37°C instead of 25°C. Given that \(K_{\mathrm{w}}\) for water is \(2.5 \times 10^{-14}\) at 37°C, calculate the pH of pure water at this temperature.

Compare the pH values for 0.10-M solutions of NaOH and of \(\mathrm{NH}_{3}\) to illustrate the difference between a strong base and a weak base.

Problem 71QP Which of the following has a higher pH: (a) 1.0 MNH3 (b) 0.20 M NaOH (Kb for NH3, = 1.8 × 10-5)?

Problem 72QP Calculate the pH for each of the following solutions at 25°C: (a) 0.10 MNH3 (b) 0.050 MC5H5N (pyridine). (Kb for pyridine = 1.7 X 10-9.)

Problem 74QP What is the original molarity of an aqueous solution of ammonia (NH3) whose pH is 11.22 at 25°C? (Use the Kb for ammonia provided in Problem 16.67.)

The pH of a 0.30-M solution of a weak base is 10.66 at \(25^{\circ} \mathrm{C}\). What is the \(K_{\mathrm{b}}\) of the base?

Calculate the pH at \(25^{\circ} \mathrm{C}\) of a 0.61-M aqueous solution of a weak base B with a \(K_{\mathrm{b}} \text { of } 1.5 \times 10^{-4}\).

Problem 76QP Determine the Kb of a weak base if a 0.19 M aqueous solution of the base at 25°C has a pH of 10.88.

Problem 78QP Write the equation relating Ka, for a weak acid and Kb for its conjugate base. Use NH3, and its conjugate acid to derive the relationship between Ka and Kb.

The following diagrams represent aqueous solutions of three different monoprotic acids: \(\mathrm{HA}, \mathrm{HB}\), and \(\mathrm{HC}\). (a) Which conjugate base \(\left(\mathrm{A}^{-}, \mathrm{B}^{-}, or \mathrm{C}^{-}\right)\) has the smallest \(K_{\mathrm{b}}\) value? (b) Which anion is the strongest base? The water molecules have been omitted for clarity.

Problem 79QP From the relationship KaKb =Kw what can you deduce about the relative strengths of a weak acid and its conjugate base?

Problem 80QP The following diagrams represent solutions of three salts NaX (X = A, B, or C). (a) Which X- has the weakest conjugate acid? (b) Arrange the three X- anions in order of decreasing base strength. The Na+ion and water molecules have been omitted for clarity.

Problem 81QP Calculate Kb for each ofthc follow ine ions: CN- .F-,CH3COO-

Problem 82QP Write all the species (except water) that are present in a phosphoric acid solution. Indicate which species can act as a Brønsted acid, which as a Brønsted base, and which as both a Brønsted acid and a Brønsted base.

Problem 83QP Write the and expressions for sulfurous acid, H2SO3.

Problem 84QP The first and second ionization constants of a diprotic acid H2A are and at a certain temperature. Under what conditions will ?

Problem 86QP What are the concentrations of , and H+ in a 0.20M KHSO4 solution? (Hint:H2SO4 is a strong acid: Ka, for = 1.3 × 10-2)

Problem 85QP Compare the pH of a 0.040M HCl solution with that of a 0.040M H2SO4 solution. (Hint: H2SO4 is a strong acid; Ka, for =1.3 × 10?2)

Problem 87QP Calculate the concentrations of and in a 0.025 M H2CO3 solution.

Problem 89QP Calculate the pH at 25°C of a 0.25 M aqueous solution of oxalic acid (H2C2O4) ( for oxalic acid are 6 5 × 10-2and 6.1 × 10-5, respectively.)

(1) Which of the following diagrams represents a solution of a weak diprotic acid? (2) Which diagrams represent chemically implausible situations? (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.)

Problem 88QP Calculate the pH at 25°C of a 0.25 M aqueous solution of phosphoric acid (H3PO4). for phosphoric acid are 7.5 × 10-3,6.25 x 10-8. and 4.8 × 10-13, respectively.)

Problem 91QP Define salt hydrolysis. Categorize salts according to how they affect the pH of a solution.

Problem 92QP Al3+ is not a Brønsted acid, but Al is. Explain.

Problem 93QP Specify which of the following salts will undergo hydrolysis:

Problem 94QP Predict the of aqueous solutions containing the following salts:

Problem 95QP Predict whether the following solutions are acidic, basic, or nearly neutral:

A certain salt, MX (containing the \(\mathbf{M}^{+}\) and \(x^{\prime}\) ions), is dissolved in water, and the pH of the resulting solution is 7.0. What can you say about the strengths of the acid and the base from which the salt is derived?

Problem 97QP In a certain experiment, a student finds that the pHs of 0.10 M solutions of three potassium salts KX, KY, and KZ are 7.0, 9.0, and 11.0. respectively. Arrange the acids HX, HY, and HZ in order of increasing acid strength.

Problem 98QP Predict whether a solution containing the salt K2HPO4 will be acidic, neutral, or basic.

Problem 99QP Predict the pH (>7,<7, or ?7) of a NaHCO3, solution.

Calculate the pH of a 0.36 M \(0.36 M \mathrm{CH}_{3} \mathrm{COONa}\) solution. \(\left(K_{\mathrm{a}} \text { for acetic acid }=1.8 \times 10^{-5} .\right)\)

Problem 101QP Calculate the pH of a 0.42 .1/ NH4C1 solution. (Kb for ammonia = 1.8 × 105)

Problem 102QP Calculate the pH of a 0.082 M NaF solution. (Kafor HF = 7.1 × 10-4.)

Problem 103QP Calculate the pH of a 0.91 M C2H5NH3I solution. (Kb for C2H5NH2 = 5.6 × 10-4)

Problem 105QP Write equations for the reactions between (a) CO2 and NaOH(aq). (b) Na2O and HNO3,(aq).

Problem 104QP Classify the following oxides as acidic, basic, amphoteric, or neutral: (a) CO2, (b) K2O, (c) CaO, (d) N2O5, (e) CO, (f) NO, (g) SnO2, (h) SO3, (i) Al2O3, (J) BaO.

Problem 106QP Explain why metal oxides tend to be basic if the oxidation number of the metal is low and tend to be acidic if the oxidation number of the metal is high. (Hint: Metallic compounds in which the oxidation numbers of the metals are low are more ionic than those in which the oxidation numbers of the metals are high.)

Problem 107QP Arrange the oxides in each of the following groups in order of increasing basicity: (a) K2O, Al2O3, BaO, (b) CrO3. CrO. Cr2O3.

Problem 108QP Zn(OH)2; is an amphoteric hydroxide. Write balanced ionic equations to show its reaction with (a) HCl. (b) NaOH [the product is ].

Problem 109QP Al(OH)3 is insoluble in water. It dissolves in concentrated NaOH solution. Write a balanced ionic equation for this reaction. What type of reaction is this?

Problem 110QP How do the chemical properties of oxides change from left to right across a period? How do they change from top to bottom within a particular group?

Problem 111QP Write balanced equations for the reactions between each of the following oxides and water: (a) Li2O, (b) CaO. (c) SO3.

Problem 112QP What are the Lewis definitions of an acid and a base? In what way are they more general than the Brønsted definitions?

In terms of orbitals and electron arrangements, what must be present for a molecule or an ion to act as a Lewis acid (use \(\mathrm{H}^{+} \text {and } \mathrm{BF}_{3}\) as examples)? What must be present for a molecule or ion to act as a Lewis base (use \(\mathrm{OH}^{-} \text {and } \mathrm{NH}_{3}\) as examples)?

Problem 115QP Describe the following reaction in terms of the Lewis theory of acids and bases:

Problem 116QP Which would be considered a stronger Lewis acid: (a) BF3 or BCl3. (b) Fe2+ or Fe3+? Explain.

Problem 117QP All Brønsted acids are Lewis acids, but the reverse is not true. Give two examples of Lewis acids that are not Brønsted acids.

Problem 114QP Classify each of the following species as a Lewis acid or a Lewis base:

Identify the Lewis acid and the Lewis base in the following reactions: (a) \(\mathrm{Fe}(s)+5 \mathrm{CO}(g) \longrightarrow \mathrm{Fe}(\mathrm{CO})_5(l)\) (b) \(\mathrm{BCl}_3(\mathrm{~g})+\mathrm{NH}_3(g) \longrightarrow \mathrm{Cl}_3 \mathrm{BNH}_3(s)\) (c) \(\mathrm{Hg}^{2+}(a q)+4 \mathrm{I}^{-}(a q) \longrightarrow \mathrm{HgI}_4^{2-}(a q)\)

Problem 119QP Identify the Lewis acid and the Lewis base in the following reactions:

Problem 121AP Which of the following diagrams best represents a strong acid. such as HCl. dissolved in water? Which represents a weak acid? Which represents a very weak acid? (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.)

\(\mathrm{H}_{2} \mathrm{SO}_{4}\) is a strong acid, but \(\mathrm{HSO}_{4}^{-}\) is a weak acid. Account for the difference in strength of these two related species.

Predict the direction that predominates in this reaction: \(\mathrm{F}^{-}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftarrows \mathrm{HF}(a q)+\mathrm{OH}^{-}(a q)\)

Problem 123AP Predict the products and tell whether the following reaction will occur to any measurable extent:

Problem 124AP In a 0.080 M NH3, solution, what percent of the NH3, is present as ?

Problem 125AP Calculate the pH and percent ionization of a 0.88 MHNO2 solution at 25°C.

A typical reaction between an antacid and the hydrochloric acid in gastric juice is \(\mathrm{NaHCO}_3(s)+\mathrm{HCl}(a q) \rightleftarrows \mathrm{NaCl}(a q)+\mathrm{H}_2 \mathrm{O}(l)+\mathrm{CO}_2(g)\) Calculate the volume (in liters) of \(\mathrm{CO}_2\) generated from \(0.350 \mathrm{~g}\) of \(\mathrm{NaHCO}_3\) and excess gastric juice at \(1.00 \mathrm{~atm}\) and \(37.0^{\circ} \mathrm{C}\).

Problem 127AP To which of the following would the addition of an equal volume of 0.60 M NaOH lead to a solution having a lower pH: (a) water, (b) 0.30 M HCl, (c) 0.70 MKOH, (d) 0.40 M NaNO3?

Like water, liquid ammonia undergoes autoionization: \(\mathrm{NH}_{3}+\mathrm{NH}_{3} \rightleftarrows \mathrm{NH}_{4}^{+}+\mathrm{NH}_{2}^{-}\) (a) Identify the Brønsted acids and Brønsted bases in this reaction. (b) What species correspond to \(\mathrm{H}^{+}\) and \(\mathrm{OH}^{-}\) , and what is the condition for a neutral solution?

Problem 128AP The pH of a 0.0642 M solution of a monoprotic acid is 3.86. Is this a strong acid?

Problem 130AP HA and HB are both weak acids although HB is the stronger of the two. Will it take a larger volume of a 0.10 M NaOH solution to neutralize 50.0 mL of 0.10 M HB than would be needed to neutralize 50.0 mL of 0.10 M HA?

Problem 131AP A solution contains a weak monoprotic acid HA and its sodium salt NaA both at 0.1 M concentration. Show that

Problem 132AP The three common chromium oxides are CrO. Cr2O3,.and CrO3,. If Cr2O3, is amphoteric, what can you say about the acid–base properties of CrO and CrO3?

Problem 134AP Use the data in Table 16.6 to calculate the equilibrium constant for the following reaction:

Problem 135AP Most of the hydrides of Group 1A and Group 2A metals are ionic (the exceptions are BeH2 and MgH2,, which are covalent compounds), (a) Describe the reaction between the hydride ion (H-) and water in terms of a Brønsted acid-base reaction.(b) The same reaction can also be classified as a redox reaction Identify the oxidizing and reducing agents.

Use the data in Table 16.7 to calculate the equilibrium constant for the following reaction: \(\mathrm{HCOOH}(a q)+\mathrm{OH}^{-}(a q) \rightleftarrows \mathrm{HCOO}^{-}(a q)+\mathrm{H}_{2} \mathrm{O}(l)\)

Problem 136AP Calculate the pH of a 0.20 M ammonium acctate (CH3COONH4) solution.

Problem 137AP Novocaine. used as a local anesthetic by dentists, is a weak base (Kb = 8.91 × 10-6). What is the ratio of the concentration of the base to that of its acid in the blood plasma (pH = 7.40) of a patient? (As an approximation, use the Ka values at 25°C.)

Problem 140AP The ion product of D2O is 1.35 x 10-15 at 25°C. (a) Calculate pD where pD = ?log [D ]. (b) For what values of pD will a solution be acidic in D2O? (c) Derive a relation between pD and pOD.

Give an example of (a) a weak acid that contains oxygen atoms, (b) a weak acid that does not contain oxygen atoms, (c) a neutral molecule that acts as a Lewis acid, (d) a neutral molecule that acts as a Lewis base, (e) a weak acid that contains two ionizable \(\mathrm{H}\) atoms, (f) a conjugate acid-base pair, both of which react with \(\mathrm{HCl}\) to give carbon dioxide gas.

Problem 139AP Which of the following is a stronger base: NH, or PH,? (Hint: The N—H bond is stronger than the P—H bond.)

Problem 142AP What is the pH of 250.0 mL of an aqueous solution containing 0.616 g of a strong acid?

(a) Use VSEPR to predict the geometry of the hydronium ion \(\left(\mathrm{H}_3 \mathrm{O}^{+}\right)\). (b) The \(\mathrm{O}\) atom in \(\mathrm{H}_2 \mathrm{O}\) has two lone pairs and in principle can accept two \(\mathrm{H}^{+}\) ions. Explain why the species \(\mathrm{H}_4 \mathrm{O}^{2+}\) does not exist. What would be its geometry if it did exist?

Problem 138AP Which of the following is the stronger base: NF3, or NH3,? (Hint: F is more electronegative than H.)

Problem 144AP HF is a weak acid, but its strength increases with concentration. Explain. (Hint: F reacts with HF to form ,. The equilibrium constant for this reaction is 5.2 at 25°C.)

Problem 145AP When chlorine reacts with water, the resulting solution is weakly acidic and reacts with AgNO3 to give a white precipitate. Write balanced equations to represent these reactions. Explain why manufacturers of household bleaches add bases such as NaOH to their products to increase their effectiveness.

Problem 146AP When the concentration of a strong acid is not substantially higher than 1.0 × 10-7 M, the ionization of water must be taken into account in the calculation of the solution’s pH. (a) Derive an expression for the pH of a strong acid solution, including the contribution to [H+] from H2O. (b) Calculate the pH of a 1.0 X 10-7 M HCl solution.

Calculate the \(\mathrm{pH}\) of a \(2.00 \mathrm{M} \mathrm{NH}_4 \mathrm{CN}\) solution.

Problem 149AP In the vapor phase, acetic acid molecules associate to a certain extent to form dimers: At 51°C. the pressure ofa certain acetic acid vapor system is 0.0342 aim in a 360-ml. flask. The vapor is condensed and neutralized with 13.8 mL of 0.0568 M NaOH. (a) Calculate the degree of dissociation (?) of the dimer under these conditions: (b) Calculate the equilibrium constant Kp for the reaction in part (a).

Calculate the concentrations of all species in a \(0.100~M~ \mathrm{H_3PO_4}\) solution.

Calculate the concentrations of all the species in a 0.100 M \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) solution.

Problem 151AP Henry’s law constant for CO2 at 38°C is 2.28 × 10-3) mol/L aim. Calculate the pH of a solution of CO2 at 38°C in equilibrium with the gas al a partial pressure of 3.20 atm.

Hydrocyanic acid (HCN) is a weak acid and a deadly poisonous compound—in the gaseous form (hydrogen cyanide), it is used in gas chambers. Why is it dangerous to treat sodium cyanide with acids (such as HCl) without proper ventilation?

Problem 153AP How many grams of NaCN would you need to dissolve in enough water to make exactly 250 mL of solution with a pH of 10.00?

Problem 154AP A solution of formic acid (HCOOH) has a pH of 2.53. How many grams of formic acid are there in 100.0 mL of the solution?

Calculate the pH of a 1-L solution containing 0.150 mole of \(\mathrm{CH}_{3} \mathrm{COOH}\) and 0.100 mole of HCl.

Problem 156AP Predict the products of the following oxides with water: Na2O, BaO, CO2. N2O5, P4O10, SO3. Write an equation for each of the reactions. Specify whether the oxides are acidic, basic, or amphoteric.

The equilibrium constant \(K_{P}\) for the reaction \(2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \rightleftarrows 2 \mathrm{H}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g})\) is \(2 \times 10^{-42}\) at \(25^{\circ} \mathrm{C}\). (a) What is \(K_{c}\) for the reaction at the same temperature? (b) The very small value of \(K_{p}\) (and \(K_{c}\)) indicates that the reaction overwhelmingly favors the formation of water molecules. Explain why, despite this fact, a mixture of hydrogen and oxygen gasses can be kept at room temperature without any change.

Problem 158AP Use Le Châtelier’s principle to predict the effect of the following changes on the extent of hydrolysis of sodium nitrite (NaNO2) solution: (a) HCl is added, (b) NaOH is added, (c) NaCl is added, (d) the solution is diluted.

Problem 160AP The disagreeable odor of fish is mainly due to organic compounds (RNH2) containing an amino group. —NH2 where R is the rest of the molecule. Amines are bases just like ammonia. Explain why putting some lemon juice on fish can greatly reduce the odor

A \(0.400 \mathrm{M}\) formic acid ( \(\mathrm{HCOOH})\) solution freezes at \(-0.758^{\circ} \mathrm{C}\). Calculate the \(K_{\mathrm{a}}\) of the acid at that temperature. (Hint: Assume that molarity is equal to molality. Carry out your calculations to three significant figures and round off to two for \(K_{\mathrm{a}}\).)

A solution of methylamine \(\left(\mathrm{CH}_{3} \mathrm{NH}_{2}\right\) has a pH of 10.64. How many grams of methylamine are there in 100.0 mL of the solution?

Problem 162AP Describe the hydration of SO2 as a Lew is acid–base reaction.

Problem 165AP Explain the action of smelling salt, which is ammonium carbonate [(NH4);CO3]. (Hint: The thin film of aqueous solution that lines the nasal passages is slightly basic.)

Both the amide ion \(\left(\mathrm{NH}_2\right)\) and the nitride ion \(\left(\mathrm{N}^{3-}\right)\) are stronger bases than the hydroxide ion and hence do not exist in aqueous solutions. (a) Write equations showing the reactions of these ions with water, and identify the Brønsted acid and base in each case. (b) Which of the two is the stronger base?

Problem 166AP About half of the hydrochloric acid produced annually in the United States (3.0 billion pounds) is used in metal pickling. This process involves the removal of metal oxide layers from metal surfaces to prepare them for coating, (a) Write the overall and net ionic equations for the reaction between iron (III) oxide, which represents the rust layer over iron, and HCl, Identify the Brønsted acid and base, (b) Hydrochloric acid is also used to remove scale (which is mostly CaCO3) from water pipes. Hydrochloric acid reacts with calcium carbonate in two stages: the first stage forms the bicarbonate ion. which then reacts further to form carbon dioxide. Write equations for these two stages and for the overall reaction, (c) Hydrochloric acid is used to recover oil from the ground. It dissolves rocks (often CaCO3) so that the oil can flow more easily. In one process, a 15 percent (by mass) HCl solution is injected into an oil well to dissolve the rocks. If the density of the acid solution is 1.073 g/mL, what is the pH of the solution ?

Problem 164AP When carbon dioxide is bubbled through a clear calcium hydroxide solution, the solution appears milky. Write an equation for the reaction, and explain how this reaction illustrates that CO2 is an acidic oxide.

Which of the following does not represent a Lewis acid-base reaction? (a) \(\mathrm{H}_{2} \mathrm{O}+\mathrm{H}^{+} \longrightarrow \mathrm{H}_{3} \mathrm{O}^{+}\) (b) \(\mathrm{NH}_{3}+\mathrm{BF}_{3} \longrightarrow \mathrm{H}_{3} \mathrm{NBF}_{3}\) (c) \(\mathrm{PF}_{3}+\mathrm{F}_{2} \longrightarrow \mathrm{PF}_{5}\) (d) \(\mathrm{Al}(\mathrm{OH})_{3}+\mathrm{OH}^{-} \longrightarrow \mathrm{Al}(\mathrm{OH})_{4}^{-}\)

Determine whether each of the following statements is true or false. If false, explain why the statement is wrong. (a) All Lewis acids are \(\text { Brønsted }\) acids. (b) The conjugate base of an acid always carries a negative charge. (c) The percent ionization of a base increases with its concentration in solution. (d) A solution of barium fluoride is acidic.

Problem 169AP How many milliliters of a strong monoprotic acid solution at pH = 4.12 must be added to 528 mL of the same acid solution at pH = 5.76 to change its pH to 5.34? Assume that the volumes are additive.

Hemoglobin (Hb) is a blood protein that is responsible for transporting oxygen. It can exist in the protonated form as \(\mathrm{HbH}^{+}\). The binding of oxygen can be represented by the simplified equation \(\mathrm{HbH}^{+}+\mathrm{O}_{2} \rightleftarrows \mathrm{HbO}_{2}+\mathrm{H}^{+}\) (a) What form of hemoglobin is favored in the lungs where oxygen concentration is highest? (b) In body tissues, where the cells release carbon dioxide produced by metabolism, the blood is more acidic due to the formation of carbonic acid. What form of hemoglobin is favored under this condition? (c) When a person hyperventilates, the concentration of \(\mathrm{CO}_{2}\) in his or her blood decreases. How does this action affect the given equilibrium? Frequently a person who is hyperventilating is advised to breathe into a paper bag. Why does this action help the individual?

Problem 174AP Use the van’t Hoff equation (see Problem 15.118) and the data in Appendix 2 to calculate the pH of water at its normal boiling point.

Problem 173AP Tooth enamel is largely hydroxyapatltc [Ca,(PO4)3OH]. When it dissolves in water (a process called demineralization), it dissociates as follows: The reverse process, called remineralization. is the body's natural defense against tooth decay. Acids produced from food remove the OH- ions and thereby weaken the enamel layer. Most toothpastes contain a fluoride compound such as NaF or SnF2. What is the function of these compounds in preventing tooth decay?

Problem 172AP Calculate the pH of a solution that is 1.00 M HCN and 1.00 M HF. Compare the concentration (in molarity) of the CN- ion in this solution with that in a 1.00 M HCN solution. Comment on the difference.

Problem 175AP Write the formulas and names of the oxides of the second period elements (Li to N). Identify the oxides as acidic, basic, or amphoteric. Use the highest oxidation state of each element.

Problem 171AP A 20.27-g sample of a metal carbonate (MCO3) is combined with 500 mL of a 1.00 M HCl solution. The excess HCl acid is then neutralized by 32.80 mL ofO.588 M NaOH. Identify M.

The atmospheric sulfur dioxide \(\left(\mathrm{SO}_2\right)\) concentration over a certain region is \(0.12 \mathrm{ppm}\) by volume. Calculate the \(\mathrm{pH}\) of the rainwater due to this pollutant. Assume that the dissolution of \(\mathrm{SO}_2\) does not affect its pressure. \(\left(K_{\mathrm{a}}\right.\) for \(\left.\mathrm{H}_2 \mathrm{SO}_3=1.3 \times 10^{-2}.\right)\)

Problem 177AP Sulfuric acid (H2SO4) accounts for as much as 80 percent of the acid in acid rain. Its first ionization is complete, producing H+ and the hydrogen sulfate ion: Its second ionization, which produces additional H+ and the sulfate ion, has an ionization constant of 1.3 × 10?2. Calculate the concentration of all species in a raindrop in which the sulfuric acid concentration is 4.00 × 10?5 M. Assume that sulfuric acid is the only acid present.