The electrolysis of aqueous solutions
2 marks · EasyDuring the electrolysis of concentrated sodium chloride solution, a total of 8 cm³ of gas is collected at the cathode. The experiment is carried out at room temperature and pressure.
Name the product formed at the cathode.
What volume of chlorine gas would you expect to collect at the anode under the same conditions?
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(a) Hydrogen · must show hydrogen
(b) 8 cm³ cm^3
Common mistakes: Stating sodium at cathode; Halving or doubling wrong volume
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Marking points
B1 (a) · 1 mark · Names hydrogen as the product at the cathode.
A1 (b) · 1 mark · Gives expected volume of gas at anode as 8 cm³ (accept 8 or 8.0 cm³). Allow follow-through if part a is correct. (follow-through)
Worked solution
a) Hydrogen is formed at the cathode.
b) The volume of chlorine gas expected at the anode is also 8 cm³, because in this electrolysis an equal volume of hydrogen and chlorine gas should be produced.