SuppEx Solution 4A E

Topic

10

Rate of Reaction

Part A Unit-based exercise
Unit 36 An introduction to rate of reaction
Fill in the blanks
1

concentration; time

2

instantaneous

3

a) the gaseous product / carbon dioxide evolved
b) loss in mass

4

a) colorimeter
b) standard alkali
c) the gaseous product / carbon dioxide evolved
1
time to reach the opaque stage

5

transmittance;

6

hydroxide; titrimetric

True or false
7

T In the oxidation of methanoic acid by bromine, the intensity of the orange colour of bromine decreases as the reaction proceeds.
When light is shone upon the reaction mixture, the absorbance of the reaction mixture is directly proportional to the colour intensity of the reaction mixture and the concentration of bromine in the reaction mixture.
Hence the progress of the reaction can be followed by using a colorimeter.

8

T Iodine and propanone react according to the following equation:
CH3COCH3(aq) + I2(aq)

CH3COCH2I(aq) + H+(aq) + I–(aq)

The concentration of H+(aq) ions in the reaction mixture increases as the reaction proceeds. Hence the progress of the reaction can be followed by measuring the concentration of H+(aq) ions by titrimetric analysis. 9

F

The hydrogen gas formed in the reaction between zinc and dilute hydrochloric acid CANNOT escape from a closed reaction vessel. Thus, the mass of the reaction mixture would NOT decrease as the reaction proceeds.

10 F

It is difficult to measure the volume of water produced from the reaction between oxalate ions and permanganate ions in aqueous solution.
1

11 T During the decomposition of hydrogen peroxide solution, oxygen gas is formed.
2H2O2(aq)

2H2O(l) + O2(g)

If the reaction vessel is a closed system, the pressure inside the vessel will increase. The progress of the reaction can be followed by measuring the pressure inside the vessel with a pressure sensor connected to a data-logger interface and a computer.
12 F

Sodium thiosulphate solution and dilute sulphuric acid react according to the following