Kinetics Self-Test 2
Answer to Prob 6, Lecture 2, p9.

2nd order in subst A; 0.5 order in subst B; overall order is 2.5

a)Calculate the values of
(i) 1/(a-x) and (ii) ln((b.(a-x))/(a.(b-x))) for each time, and plot these quantities (vertically) against time (horizontally). Inspect the graphs to see which gave a straight line. If (i) is straight, it is second order, equal. If (ii) is straight, it is second order unequal. If both appear straight, not enough measurements have been taken.

b)Reaction is second order equal. No second reactant is given, so first, or second order equal is expected. 2k = 0.288 L/mol.s

• 1

The concentration/time graph for a zero order reaction has which form?

All are plots of reactant concentration (vertically) against time (horizontally).

 a b c d e f

a
b
c
d
e
f

Answer to Prob 9, L2, p12

693 seconds

Answer to Prob 10, L2, p13

Half life = 23.1 s
at 100 s, c = 0.003 mol/L
time to fall 0.01 to 0.002 = 53.6 s

i) 66.7 s
ii) 6667 s.

a) 0.0197 L/mol.s
b) 508 s
c) 0.039 s-1 ; 17.6 s
d) 0.0578mol/L
e) 546 s

• 2

A reaction of the type

is first order in each reactant, and starts off with [A]0 = [B]0 = 0.06 mol/L. If [A]t drops to 0.022 mol/L in 100 s, calculate 2k in L/mol.s units.

• 3 Using the correct rate constant, and starting with [A]0 = 0.06 mol/L, calculate the concentration of A in mol/L after 200s.

• 4

For the same reaction, calculate the time, in seconds, for [A] to drop from 0.022 to 0.0022 mol/L