Page 197 - Basic physical chemistry for the atmospheric sciences

Answers, hints, and solutions to exercises

[H30 + (aq)] = (5 . 6 0 x 1 0 - 10) x (2.00)
= l l . 2 X l Q - IO
:.pH = - log[H 30 + ( aq)]

= - log(l l .2 x 1 0 - 10)
= - ( l . 05 - I O )

Therefore,
pH = 8 . 9 5

5 . 1 8 . (a) 2 . 6 x w - 4 M . (b) pH would decrease by 0 . 2 2 pH units.
(c) pH would increase by 0. 1 4 pH units . (c) 2 . 6 x 1 0 - 4 M.
5
Hints: See Exercises . 4 and . 5 .
5
o
3
5 . 1 9 . Range f p H values is . 7 to 6 . 5 . A pH of 6.5 would not be
achieved because buffering capacity of C02 in the air would
hold pH to ::::; 5 . 7 .

CHAPTER 6
1
6. 2 . (a) The oxidation half-reaction is
+
Cu ( aq � ) Cu2 + (aq) + e­
The reduction half-reaction is
Fe3 + ( aq) + e - � Fe 2 + (aq)
3
Fe + (aq) is the oxidant and Cu + (aq) the reductant.
(b) The oxidation half-reaction is

Zn(s)� Zn 2 + (aq) + 2e -
The reduction half-reaction is
2H + (aq) + 2e - � H2(g)

H + (aq) is the oxidant and Zn(s) the reductant.
6. 1 3 . (a) Oxidation number of oxygen and nitrogen are - 2 and 3 ,
respectively . (b) Oxidation number f oxygen and nitrogen
o
are - 2 and 5, respectively . (c) Oxidation number of hydro­
ge , oxygen and nitrogen are I , - 2 , and 5 , respectively.
n
(d) Oxidation number of hydrogen, oxygen, and sulfur are
, - 2 , and 4, respectively.
I