Chemistry 12
Unit 1 Reaction Kinetics
Worksheet 1.1 Calculating Reaction Rate
1.
Which of the following units can be used to describe rate?
g/min, mol/s, g/L, mol/L, L/s, mol/L/s
2.
A chemist wishes to determine the rate of reaction of magnesium with hydrochloric acid. The
equation for the reaction is:
Mg(s) + 2H+(aq)  Mg2+(aq) + H2(g)
A piece of magnesium was dropped into 1.00 L of 0.100 M HCl and the following data were
collected:
Time Mass of Mg
3.
0s
0.012 g
2s
0.010 g
6s
0.006 g
8s
0.004 g
a)
Calculate the rate of reaction in terms of moles of Mg consumed per second.
b)
As this magnesium reacts with hydrochloric acid, does the pH increase or decrease?
Support your answer with an explanation.
The decomposition of N2O5 occurs according to the following equation:
2N2O5  4NO2 + O2
The following data are collected for the above reaction:
Time (sec) Moles of N2O5
0s
1.62
200 s
1.46
400 s
1.30
600 s
1.14
Using the above data, calculate the reaction rate.
WS 1.1b Calculating Reaction Rates.doc
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Chemistry 12
4.
5.
Unit 1 Reaction Kinetics
A strip of magnesium was cut into 4 pieces, each of length 1.0 cm and mass of 0.00864 g. Each
piece was placed into a test tube containing 5.0 mL of different concentrations of HCl. The time
required for each piece of magnesium to be completely consumed was recorded:
Trial
[HCl]
Time (s)
1
0.50 M
200
2
1.0 M
38
3
3.0 M
12
4
6.0 M
6
a)
Calculate the rate of reaction for magnesium in 3.0 M HCl.
b)
How does the [HCl] affect the reaction rate?
An experiment is performed by displacement of water to determine the rate of the following
reaction:
Zn(s) +2HCl(aq)  H2(g) + ZnCl2(aq)
Time
(s)
Volume of H2
(mL)
0.0
0.0
10.0
21.1
20.0
40.9
30.0
60.0
40.0
77.6
a)
Calculate the average rate of formation of H2 in mL/s for the time interval between
20 and 40 seconds.
b)
How does the rate of this reaction change as the reaction proceeds? Explain why.
WS 1.1b Calculating Reaction Rates.doc
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Chemistry 12
6.
Unit 1 Reaction Kinetics
Consider the reaction:
A + 2B  3C
If the rate of consumption of A is 5.6 × 10–3 mol/s, what are the rates of B and C?
7.
Consider the following reaction:
Mg(s) + 2HCl(aq)  MgCl2(aq) + H2(g)
A 0.024 g sample of Mg reacts completely with HCl in 14.0 s. Calculate the average rate of
consumption of HCl in mol/s.
8.
Consider the following reaction:
3Cu(s) + 8HNO3(aq)  3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l)
A piece of copper is added to a nitric acid solution in an open beaker, allowing the NO(g) to
escape. The following data was obtained:
9.
a)
Calculate the reaction rate for the time period 2.0 to 6.0 min.
b)
Calculate the mass of copper consumed in the first 5 minutes.
Consider the following reaction:
C12H22O11(s)  11H2O(g) + 12C(s)
The rate of decomposition of C12H22O11 is 0.75 mol/min. What mass of C is produced in 10.0
seconds?
WS 1.1b Calculating Reaction Rates.doc
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Chemistry 12
10.
Unit 1 Reaction Kinetics
Consider the reaction:
2Al(s) + 6HCl(aq)  2AlCl3(aq) + 3H2(g)
A 10.0 g sample of Al reacts completely in excess HCl in 300.0 s. What is the rate of production of
H2 in g/s ?
11.
Consider the reaction:
2H2O(l)  2H2(g) + O2(g)
The rate of production of O2 is 1.2 × 10–2 mol/s . How many seconds will it take to decompose
100.0 g H2O?
12.
Consider the following reaction in an open flask:
CaCO3(s) + 2HCl(aq)  CaCl2(aq) + H2O(l) + CO2(g)
A 155.0 g sample of CaCO3(s) is placed in the flask and HCl(aq) is added. The reaction consumes
HCl(aq) at an average rate of 0.200 mol/min for 10.0 min. What mass of CaCO3(s) remains?
WS 1.1b Calculating Reaction Rates.doc
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