1.
The compounds with the molecular formula C4H9Br all undergo nucleophilic substitution
reactions when warmed with sodium hydroxide solution. The equation for each of the
reactions is
C4H9Br + OH–  C4H9OH + Br–
When the reaction of one of these compounds was investigated the following kinetic data were
obtained.
Experiment number
1
2
3
(a)
Initial [C4H9Br]
/ mol dm–3
0.010
0.020
0.020
Initial [OH–]
/ mol dm–3
0.010
0.010
0.020
Initial rate of reaction
/ mol dm–3 min–1
2.0 × 10−3
4.0 × 10−3
4.0 × 10−3
Deduce the order of reaction with respect to C4H9Br
1st order with respect to C4H9Br, concentration doubles and rate doubles/show math.
(b)
Deduce the order of reaction with respect to OH− and explain your answer.
Zero order with respect to OH−, concentration doubles in experiments 2 and 3 and the rate
does not change/show math.
(d)
State the rate expression for the reaction.
Rate = k[C4H9Br] or rate=k[C4H9Br][OH]0
(e)
Calculate the value of the rate constant for the reaction and state its units.
k = 0.20 min-1
1
2.
The reaction between NO2 and F2 gives the following rate data at a certain temperature.
What is the order of reaction with respect to NO2 and F2?
[NO2]/ mol dm−3
[F2]/ mol dm–3
Rate /mol dm–3
min–1
0.1
0.2
0.1
0.2
0.2
0.4
0.1
0.4
0.2
(a)
Deduce the order of reaction with respect to NO2
2nd order with respect to NO2, concentration doubles rate quadruples/show math.
(b)
Deduce the order of reaction with respect to F2 and explain your answer.
1st order with respect to F2, concentration doubles rate doubles/show math.
(d)
State the rate expression for the reaction.
Rate = k[NO2]2[F2]
(e)
Calculate the value of the rate constant for the reaction and state its units.
k = 50 mol-2 dm6 min-1
2
3.
Nitrogen(II) oxide reacts with hydrogen as shown by the following equation.
2NO(g) + 2H2(g) → N2(g) + 2H2O(g)
The table below shows how the rate of reaction varies as the reactant concentrations vary.
Experiment
1
2
3
4
(a)
Initial [NO] /
mol dm–3
0.100
0.100
0.200
0.300
Initial /[H2]mol
dm–3
0.100
0.200
0.100
0.100
Initial rate /
mol N2 dm–3 s–1
2.53 × 10–6
5.05 × 10–6
10.10 × 10–6
22.80 × 10–6
Determine the order of reaction with respect to NO and with respect to H2.
Explain how you determined the order for NO.
NO 2nd order, concentration doubles rate quadruples
H2 1st order, concentration doubles rate doubles
(b)
Write the rate expression for the reaction.
Rate = k[NO]2[H2]
(c)
Calculate the value for the rate constant, including its units.
k= 2.53 x10-3 mol-2 dm6 s-1
(f)
Deduce how the initial rate of formation of H2O(g) compares with that of N2(g) in
experiment 1. Explain your answer.
The rate should be the double because stoichiometrically they are 2:1/show conversion
3
4.
Gaseous hydrogen iodide, HI, decomposes into its elements when heated. The decomposition
was investigated in a series of experiments carried out at the same temperature. The following
data was obtained.
Experiment number
Initial (HI) / mol dm−3
1
2
3
4
(a)
Initial rate of reaction / mol dm−3 s−1
2.2 × 10−3
6.6 × 10−3
2.2 × 10−2
4.4 × 10−3
1.1 × 10−6
9.9 × 10−6
1.1 × 10−4
to be determined
Write the equation for the decomposition of hydrogen iodide.
2HI(g)  H2(g) + I2(g)
(b)
Deduce the order of the reaction and explain your answer.
2nd order with respect to HI, concentration triples and rate triples/[3]m = 9
(c)
State the rate expression for the reaction.
Rate = k[HI]2
(d)
Determine the initial rate of reaction in experiment 4.
k = 0.23 mol-1 dm3 s-1
Rate = 4.5 x10-6 mol dm-3 s-1
4