1. a) Assume that phenol, C 6 H 5 OH (s), can form from C(s), O2(g) och H2(g) at
ID: 1035557 • Letter: 1
Question
1. a) Assume that phenol, C6H5OH (s), can form from C(s), O2(g) och H2(g) at 45 C and 1 bar. Use standard enthalpies of formation and standard sntropies at 25 C to calculate the maximum useful(non-expansion) work that can be done when 1 mol C6H5OH(s) is formed at 45 C. b) is the formation of phenol spontaneous at 45 C and 1 bar? motivate your answer.
2. a) the reaction A + B + C? D is of zeroth order with respect to reactant A. experimental studies show the concentration of A decreased from 30 mol dm-3 to 10 mol dm-3 in 60 s. what is the rate constant with respect to A? b) what is the half-life of A?
Explanation / Answer
1.)
The standard entropy change of formation, ?S? , of phenol, C6H5OH(s) at 343 K is –385 J K-1 mol–1 . Hence the process of formation of phenol is non-spontaneous in nature at 45oC and 1 bar pressure.
2.)
a.) The formula for rate constant for a zero order reaction is -
[A]t - [A]0 = - kt
where-
So, from the above equation
k = 1/3 M/s
b.) Half life of A
t1/2 = [A0] / 2k
so,
t1/2 = 45 seconds
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