MYP 10 Chemistry 2013-14
Kinetics Worksheet 3
Name: _________________________________ ( )
Class: _________ Date: _____________
_________________________________________________________________________________
1. The decomposition of aqueous hydrogen peroxide is catalysed by adding a small amount of
manganese(IV) oxide.
(a) Write a balanced equation, including state symbols for the reaction which takes place when hydrogen
peroxide decomposes.
(b) Briefly explain how manganese(IV) oxide increase the rate of decomposition of hydrogen peroxide.
2. The graph below was obtained when calcium carbonate reacted with dilute hydrochloric acid, under two
different conditions, X and Y.
(a)(i) Name the gas produced in the reaction.
(ii) Write a balanced equation for the reaction occurring.
(b) Identify the volume of gas produced and the time taken for the reaction under condition X to be
complete.
(c)(i) Explain the shape of curve Y in terms of collision theory.
(ii) Suggest two possible reasons for the differences between curves X and Y.
3(a) Magnesium carbonate was added to equal volumes of 3 mol/dm3 hydrochloric acid and 3 mol/dm3
sulfuric acid separately. When the reaction were completed, some solids remained.
(a) Write the equations for the reactions.
(i) In which acid would the reaction be faster at the start. Explain your answer.
(ii) The rate of reaction can be determined by measuring the volume of gas liberated at certain time
intervals. Sketch the graphs you would expect for the two reactions. Use the same axes for the two
acids and label your graphs.
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Volume of carbon dioxide (cm3)
(b) When the carbonates of some metals were heated they decompose to produce carbon dioxide.
In one experiment, 0.01 mol of magnesium carbonate and 0.01 mol of copper(II) carbonate were
heated separately to the same temperature. The volume of carbon dioxide produced was measured at
certain time interval. A graph was plotted.
copper(II)
carbonate
magnesium
carbonate
Time (minutes)
(i) Which carbonate decomposed at a faster rate? Explain the difference in their rate of decomposition.
(ii) Explain why the same number of moles of carbonate had to be used rather tha the same mass of
carbonate to get a fair comparison.
(iii) Apart from the volume of the carbon dioxide collected, how would you tell the decomposition of
copper(II) carbonate was complete?
4. The gas-phase reaction of hydrogen and iodine monochloride,
H2(g) + 2ICl(g)  2 HCl(g) + I2(g)
is first order in ICl.
(a) What is the rate law?
(b) What are the units of the rate constant?
5(a) Determine the rate law for the following reaction
A + 2B  AB2
A (molarity) B (molarity) Rate (M/s)
2
2
5
2
4
10
4
4
40
(i) Using the data from the problem, calculate the rate constant
(ii) What would the rate be if the [A] = 2.5 mol dm-3 and [B] = 3.0 mol dm-3?
(b) Determine the rate law for the following reaction
C2 + 2 D  2 CD
C2
D
Rate (M/s)
(molarity)
(molarity)
0.5
0.01
5
0.5
0.02
5
1.0
0.02
10
(i) Using the data from the problem, calculate the rate constant
(ii) What would the rate be if the [C] = 2.5 mol dm-3 and [D] = 3.0 mol dm-3?
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6. At 6000C, acetone (CH3COCH3) decomposes to ketone (CH2=C=O) and various hydrocarbons.
Given the initial rate data in the table:
(a) Determine the rate constant.
(b) Calculate the rate constant.
(c) Calculate the rate of decomposition when the acetone concentration is 1.8 x 10-3 M.
Experiment
1
2
Initial
Initial Rate of Decomposition
[CH3COCH3] of CH3COCH3 (M/s)
6.0 103
5.2 105
9.0 103
7.8 105
[(b)8.7 x 10-3/s(c)1.6x10-5M/s]
7. Initial rate data at 250C are listed in the table for the reaction:
NH4+(aq) + NO2-(aq)  N2(g) + 2H2O(l)
Experiment
1
2
3
Initial [NH4+] Initial [NO2-]
0.24
0.12
0.12
0.10
0.10
0.15
Initial Rate of Consumption
of NH4+ (M/s)
7.2 106
3.6 106
5.4 106
(a) What is the rate law?
(b) What is the value of the rate constant?
(c) What is the reaction rate when the concentrations are [NH4+] = 0.39 M and [NO2-] = 0.052 M?
[(b)3.0 x 10-4/ (M.s)(c)6.1x10-6M/s]
8. The initial rates listed in the table were determined for the reaction:
2 NO(g) + Cl2(g)  2 NOCl(g)
Experiment
1
2
3
Initial [NO]
Initial [Cl2]
0.13
0.26
0.13
0.20
0.20
0.10
Initial Rate of Consumption
of Cl2 (M/s)
1.0 102
4.0  10 2
5.0 103
(a) What is the rate law?
(b) What is the value of the rate constant?
(c) What is the reaction rate when both reactant concentrations are 0.12M?
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9. Sorbital (C6H12O6) is a substance used as a sweetener in foods, is prepared by reaction of glucose with
hydrogen in the presence of a catalyst:
C6H12O6(aq) + H2()  C6H14O6(aq)
Which of the following quantities are affected by the catayst?
(a) Rate of the forward reaction.
(b) Rate of the reverse reaction.
(c) Spontaneity of the reaction.
(d) ΔHƟ
(e) ΔSƟ
(f) ΔGƟ
(g) the equilibrium constant.
(h) time required to reach equilibrium.
10(a) Consider the following reaction taking place at 3750C in a 1.00 dm3 closed container.
Cl2(g) + SO2(g)
SO2Cl2(g) ΔHƟ = - 84.5 kJ
(i) Deduce the equilibrium constant expression, Kc , for the reaction.
(ii) If the temperature of the reaction is changed to 3000C, predict, stating a reason in each case, whether the
equilibrium concentration of SO2Cl2 and the value of Kc will increase or decrease.
(iii) If the volume of the container is changed to 1.50 dm3, predict, stating a reason in each case, how this
will affect the equilibrium concentration of SO2Cl2 and the value of Kc.
(iv) Suggest, stating a reason, how the addition of a catalyst at constant pressure and temperature will affect
the equilibrum concentration of SO2Cl2.
(b) Graphing is an important method in the study of rates of chemical reaction. Sketch a graph to show how
the reactant concentration changes with time in a typical chemical reaction taking place in solution. Show
how the rate of the reaction at a particular time can be determined.
(c) A solution of hydrogen peroxide, H2O2, is added to a solution of sodium iodide, NaI, acidified
with hydrochloric acid, HCl. The yellow colour of the iodine, I2, can be used to determine the rate of
reaction.
H2O2(aq) + 2NaI(aq) + 2HCl(aq)  2NaCl(aq) + I2(aq) + 2H2O(l)
The experiment is repeated with some changes to the reaction conditions. For each of the changes that
follow, predict, statng a reason, its effect on the rate of reaction.
(i)
The concentration of H2O2 is increased at constant temperature.
(ii)
The solution of NaI is repared from a fine powder instead of large crystals.
(d) Explain why the rate of reaction increases when the temperature of the system increases.
[SL paper 2, Nov 09]
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