Chapter 16 Text

Exercises 655
16.28 Complete the following table by calculating the missing
entries. In each case indicate whether the solution is acidic
or basic.
pH
6.21
pOH
10.13
[H+]
3.5 X 10~3 M
[OH']
5.6 X 10~4 M
acidic
or basic?
16.29 The average pH of normal arterial blood is 7.40. At normal
body temperature (37°C), Kw = 2.4 x 10"14. Calculate
[H+] and [OH~] for blood at this temperature.
16.30 Carbon dioxide in the atmosphere dissolves in raindrops
to produce carbonic acid (H2CO3), causing the pH of
clean, unpolluted rain to range from about 5.2 to 5.6.
What are the ranges of [H+] and [OH~] in the raindrops?
Strong Acids and Bases
16.31 (a) What is a strong acid? (b) A solution is labeled 0.500 M
HC1. What is [H+] for the solution? (c) Which of the following
are strong acids: HF, HC1, HBr, HI?
16.32 (a) What is a strong base? (b) A solution is labeled
0.125 M Sr(OH)2. What is [OH~] for the solution? (c) Is
the following statement true or false? Because Mg(OH)2
is not very soluble, it cannot be a strong base. Explain.
16.33 Calculate the pH of each of the following strong acid solutions:
(a) 8.5 X 10~3MHBr; (b) 1.52 g of HNO3 in
575 mL of solution; (c) 5.00 mL of 0.250 M HC1O4 diluted
to 50.0 mL; (d) a solution formed by mixing 10.0 mL
of 0.100 M HBr with 20.0 mL of 0.200 M HCL
16.34 Calculate the pH of each of the following strong acid solutions:
(a) 0.0575 M HNO3; (b) 0.723 g of HC1O4 in 2.00 L
of solution; (c) 5.00 mL of 1.00 M HC1 diluted to 0.750 L;
(d) a mixture formed by adding 50.0 mL of 0.020 M HC1
to 125 mL of 0.010 M HI.
16.35 Calculate [OH'] and pH for (a) 1.5 x 10~3 M Sr(OH)2;
(b) 2.250 g of LiOH in 250.0 mL of solution; (c) 1.00 mL
of 0.175 M NaOH diluted to 2.00 L; (d) a solution
formed by adding 5.00 mL of 0.105 M KOH to 15.0 mL
of 9.5 X 10~2MCa(OH)2.
16.36 Calculate [OH""] and pH for each of the following strong
base solutions: (a) 0.0050 M KOH; (b) 2.055 g of KOH in
500.0 mL of solution; (c) 10.0 mL of 0.250 M Ca(OH)2
diluted to 500.0 mL; (d) a solution formed by mixing
10.0 mL of 0.015 M Ba(OH)2 with 30.0 mL of
7.5 X 1Q-3 M NaOH.
16.37 Calculate the concentration of an aqueous solution of
NaOH that has a pH of 11.50.
16.38 Calculate the concentration of an aqueous solution of
Ca(OH)2 that has a pH of 12.00.
[16.39] Calculate the pH of a solution made by adding 15.00 g of
sodium hydride (NaH) to enough water to make 2.500 L
of solution.
[16.40] Calculate the pH of a solution made by adding 2.50 g of
lithium oxide (Li2O) to enough water to make 1.200 L of
solution.
Weak Acids
16.41 Write the chemical equation and the Ka expression for
the ionization of each of the following acids in aqueous
solution. First show the reaction with H+(aq) as a product
and then with the hydronium ion: (a) HBrO2;
(b)HC3H502.
16.42 Write the chemical equation and the Ka expression for the
acid dissociation of each of the following acids in aqueous
solution. First show the reaction with H+(aq) as a
product and then with the hydronium ion: (a) HQH5O;
(b) HC03~.
16.43 Lactic acid (HC3H5O3) has one acidic hydrogen. A 0.10 M
solution of lactic acid has a pH of 2.44. Calculate Ka.
16.44 Phenylacetic acid (HC8H7O2) is one of the substances
that accumulates in the blood of people with phenylketonuria,
an inherited disorder that can cause mental
retardation or even death. A 0.085 M solution of
HC8H7O2 is found to have a pH of 2.68. Calculate the
Ka value for this acid.
16.45 A 0.200 M solution of a weak acid HA is 9.4% ionized.
Using this information, calculate [H+], [A~], [HA], and Ka
for HA.
16.46 A 0.100 M solution of chloroacetic acid (C1CH2COOH)
is 11.0% ionized. Using this information, calculate
[ClCH2COCn, [H+], [C1CH2COOH], and Ka for
chloroacetic acid.
16.47 A particular sample of vinegar has a pH of 2.90. Assuming
that acetic acid is the only acid that vinegar contains
(Ktt = 1.8 X 10^5), calculate the concentration of acetic
acid in the vinegar.
16.48 How many moles of HP (Ka = 6.8 X 10~4) must be present
in 0.500 L to form a solution with a pH of 2.70?
16.49 The acid-dissociation constant for benzole acid (HC7HsO2)
is 6.3 X 10~5, Calculate the equilibrium concentrations of
H3O+, C7H5O2~, and HC7H5O2 in the solution if the initial
concentration of HC7H5O2 is 0.050 M.
16.50 The acid-dissociation constant for hypochlorous acid
(HC1O) is 3.0 X 1CT8. Calculate the concentrations of
H3O+, C1O~, and HC1O at equilibrium if the initial concentration
of HC1O is 0.0075 M.
16.51 Calculate the pH of each of the following solutions (Ka
and Kb values are given in Appendix D): (a) 0.095 M propionic
acid (HC3H5O2); (b) 0.100 M hydrogen chrornate
ion (HCrO4~);