MULUNGUSHI UNIVERSITY
SCHOOL OF NATURAL AND APPLIED SCIENCES
ACADEMIC YEAR 2024/2025
SEMESTER II
CHE112: INTRODUCTION TO CHEMISTRY II
1st March , 2025
TUTORIAL SHEET 1:
NOTE: Discuss during tutorial sessions.
1. Define reaction rate. Distinguish between the initial rate, average rate and
instantaneous rate of a chemical reaction.
2. A first-order reaction is 38.5% complete in 480 s.
a. Calculate the value of the rate constant.
b. What is the value of the half-life.
c. How long will it take for the reaction to reach 95% completion.
3. Given reaction rate data for:
F2(g) + 2ClO2(g) → N2(g) + FClO2(g)
Experiment
1
2
3
[𝐹2 ] (M)
0.10
0.10
0.20
[𝐶𝑙𝑂2] (M)
0.010
0.040
0.010
Initial Rate (M/s)
1.2 x 10-3
4.8 x 10-3
2.4 x 10-3
(a) Determine the order of each reactant and the overall reaction order.
(b) Write the rate law for the reaction.
(c) Calculate the rate constant, K and state its units.
4. Consider the table of initial rate for the reaction between hemoglobin (Hb) and
carbon monoxide.
Experiment
[HB]o, mol/L
[CO] o, mol/L
Initial Rate, mol/(L . s)
1
2.21
1.00
0.619
2
4.42
1.00
1.24
3
3.36
2.40
2.26
(a) Order with respect to HB:
(b) Order with respect to CO:
1
(c) Rate law for this reaction:
(d) Value and units for the rate constant:
5. The decomposition reaction of hydrogen iodide at 508oC.
2HI (g) → H2 (g) + I2 (g)
Time (s)
0
50
100
150
200
250
300
350
Concentration 0.1000 0.0716 0.0558 0.0457 0.0387 0.0336 0.0296 0.0265
of HI (M)
(a) Plot the concentration time graph.
(b) Calculate from the graph;
i. Average rate between 50 and 250 seconds
ii. Instantaneous rate at 200 s
iii. Initial instantaneous rate
6. The rate of this reaction depends only on NO2: NO2 + CO →NO + CO2. (Use the
integrated rate laws and graphing to get orders).
The following data were collected.
Time (s)
[NO2] (mol/L)
0
0.500
1200.
0.444
3000.
0.381
4500.
0.340
9000.
0.250
18000.
0.174
a. Order with respect to NO2:
b. Rate law for this reaction:
c. [NO2] at 2.7 x 104 s after the start of the reaction.
7. A cache of Hebrew manuscripts known as the Dead Sea Scroll was found in 1947. The
specific activity of Carbon-14 in the linen wrappings of the book of Isaiah was about
0.200 disintegration per second per gram (dps g-1.). Carbon-14 in living materials has
a specific activity of 0.255 dps g-1. The half-life of Carbon-14 is
5.73 x103 years. Carbon-14 decay by First order rate law. Calculate the approximate
age of the linen.
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8. Consider the reaction:
2NO2 (g) → 2NO(g) + O2 (g)
The rate constant at 650 K is 1.66 s-1. The rate constant at 7000 K is 7.39 s-1. Calculate
the activation energy.
9. A certain gas reaction has the following kinetic data:
T(K)
650.0
750.0
800.0
k (s-1)
2.24 x10-6
0.00112
0.01405
Determine the activation energy and the rate constant A.
10. Draw the concentration versus rates of reaction graphs for zero, first and second
order reaction.
11. Consider the exothermic reaction between reactants A and B?
A + B → E (fast)
E + B → C + D (slow)
a. What is the order with respect to reactants A and B?
b. What is the rate law for the reaction?
c. Sketch a potential energy diagram for this reaction. Identify the activation energy
for the overall forward reaction. Identify the location of reactants,
intermediate(s), activated complex(es), and products.
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