Page 147 - Bruno Linder Elementary Physical Chemistry

August 18, 2010 11:37 9in x 6in b985-appA Elementary Physical Chemistry

132 Elementary Physical Chemistry

12. NH 4 Cl(s) dissociates in accordance with the reaction

NH 4 Cl(s) NH 3 (g) + HCl(g)

3
The total pressure at 700K is 6.00 × 10 Pa and at 730K it is 11.00 ×
3
o
5
10 Pa. The standard state pressure is P = 101.2 × 10 Pa.
(a) Calculate the equilibrium constant K at T = 700 K and the

equilibrium constant K at T = 730 K.

o
(b) Calculate the standard enthalpy change, ∆H , for this reaction.
o
[Assume that within this temperature range ∆H is constant]
13. Calculate the standard potentials for the cell reactions
(a) Fe(s) + Pb 2+ (aq) → Fe 2+ (aq) + Pb(s)
(b) H 2 (g) + I 2 (g) → 2HI(aq)
14. Calculate the equilibrium constants at 298 K for the reactions
(a) Sn(s) + Sn 4+ (aq) → 2Sn 2+ (aq)
(b) Fe(s) + Hg 2+ (aq) → Hg(l) + Fe 2+ (aq)
+
(c) Cu 2+ (aq) + Cu(s) → 2Cu (aq)

Problem Set V. Chapter 7
1. The rate of formation of C in the reaction 3A + B → 2C + D is
2mol L −1 −1 . What is the rate of formation of D? What is the rate
s
of disappearance of A?
2. The reaction of Problem 1 was found to obey the reaction law r =
k[A][B][D]. What are the units of k?
3. The rate of reaction 2N 2O 5 (g) → 4NO 2 (g) + O 2 is first order in N 2 O 5,
i.e. r = k A [N 2 O 5 ]. The rate constant k A =3.46 × 10 −5 −1 at 298 K.
s
(a) Calculate t 1/2 for this reaction
(b) If the initial pressure of N 2 O 5 is 75.0 kPa, what is the total pressure
of the gases?

1. after 10 seconds?
2. after 1 hour?
4. The oxidation of ethanol is first order in C 2 H 5 OH. If the concentration
4
of ethanol decreased from 440mmol L −1 to 112mmol L −1 in 1.22×10 s,
calculate the rate constant of the reaction.