Aristo Book 5 experiment answer

Topics: Chemical reaction, Chemistry, Reaction rate Pages: 15 (1994 words) Published: October 6, 2013
HKDSE CHEMISTRY – A Modern View (Chemistry)
Experiment Workbook 5
Suggested answers

Chapter 52 Importance of industrial processes
Chapter 53 Rate equation
Experiment 53.1 Determining the rate equation of a reaction using method of initial rate (A microscale experiment) 1
Chapter 54 Activation energy
Experiment 54.1 Determining the activation energy of a chemical reaction 3
Chapter 55 Catalysis and industrial processes
Experiment 55.1 Investigating the action of a catalyst
6
Experiment 55.2 Investigating homogeneous catalysis
8
Experiment 55.3Investigating ways to change the rate of a reaction with a suitable catalyst 9
Experiment 55.3 Sample laboratory report
13
Experiment 55.4Preparing ethanol by fermentation
16
Chapter 56 Industrial processes
Chapter 57 Green chemistry for industrial processes

Chapter 53Rate equation

Experiment 53.1Determining the rate equation of a reaction using method of initial rate (A microscale experiment)

7. and 11.(a)
Well number
1
2
3
4
5
6
7
8
Number of drops of 0.5 M Na2S2O3(aq)
10
9
8
7
6
5
4
3
Time, t (s)
14.2
15.8
17.8
20.4
23.8
28.6
35.7
47.6
(s1)
0.070
0.063
0.056
0.049
0.042
0.035
0.028
0.021

10. and 12.(a)
Well number
1
2
3
4
5
6
7
8
Number of drops of 1.0 M H2SO4(aq)
10
9
8
7
6
5
4
3
Time, t (s)
59.4
59.7
60.0
60.7
59.9
60.0
61.0
60.5
(s1)
0.017
0.017
0.017
0.016
0.017
0.017
0.016
0.017

11.(a)inversely
(b)

(c)1

12.(b)0
(c)From the results in Table 53.2, the readings of time are close, indicating that the reaction is of zeroth order with respect to H+(aq).

13.Rate = k[S2O32(aq)]

14.S2O32(aq) + 2H+(aq)  S(s) + SO2(g) + H2O(l)

15.In this experiment, the time for the formation of a fixed, but small amount of insoluble sulphur precipitate is measured. The shorter the time, the faster is the reaction. It is assumed that the extent of reaction is still small when the time is recorded, so that the time recorded can be used as a measurement of initial rate of the reaction. Chapter 54Activation Energy

Experiment 54.1Determining the activation energy of a chemical reaction

5.
Temperature of the reaction mixture (°C)
15
25
35
45
55
Time for the appearance of dark blue colour (s)
679
(at 11°C)
232
(at 27°C)
112
(at 37°C)
80
(at 43°C)
33
(at 56°C)

6.(a)rate constant; activation energy; Universal gas constant; temperature;
(b)
log ()
2.83
2.37
2.05
1.90
1.52

3.52
3.33
3.23
3.16
3.04

(c)

(d)2750
(e)slope = 2750 =
Ea = 2750 × 2.3 × 8.314 J mol1
= 52 586 J mol1
= 52.6 kJ mol1
7.Arrhenius equation; log k = log A
8.straight line;

9.S2O82(aq) + 2I(aq)  2SO42(aq) + I2(aq)

10.To monitor the formation of iodine from the reaction of S2O82(aq) ions and I(aq) ions.

11.When all S2O82(aq) ions have reacted, any iodine formed will turn the starch solution dark blue. The time for this colour change is a measure of the rate of reaction shown in question 9. (Note: The reaction rate is inversely proportional to the time taken for the starch solution to turn dark blue.)

12.The amount of reactants used in each experiment may not be exactly the same.
There may be an error in measuring or reading the temperatures from the thermometers.
As the colour change of the solution mixture is not a sudden one, especially at low temperatures, there may be an error in recording the time of colour change.

Chapter 55Catalysis and industrial processes

Experiment 55.1Investigating the action of catalyst

1.(b)No.

5.(b)
Time (s)
10
20
30
40
50
60
Volume of O2(g) released (cm3), with the addition of 0.5 g MnO2(s) 30
60
85
95
96
96
Time (s)
70
80
90
100
110
120
Volume of O2(g) released (cm3), with the addition of 0.5 g MnO2(s) 96

6.(b)
Time (s)
10
20
30
40
50
60
Volume of O2(g) released (cm3), with the addition of...
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