Question
If a concentrated solution of potassium bromide is electrolysed, what gas will be produced at the cathode? Answer in words not symbols
Answer
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(215 Votes)
Jeremy
Master · Tutor for 5 years
Answer
So, in summary, at the cathode of an electrolysis cell containing a concentrated solution of potassium bromide (KBr), the gas that would be formed is Hydrogen.
Explanation
Electrolysis of an ionic compound involves oxidation and reduction. In a KBr (Potassium Bromide) solution, there would be Potassium (K) ions and Bromide (Br) ions existing in the solution. According to the electrochemical series: hydrogen is stronger than potassium for reduction, meanwhile bromide is stronger than hydroxyl ions for oxidation. Consequently, the potassium ions would prefer hydrogen to receive electrons during the electrolysis process. As a result, after applying voltage and current to start electrolysis, on the reduction side (at the Cathode which attracts the positively charged ions) these Hydrogen ions would gain an electron to turn themselves into Hydrogen gas. At anode side, the oxidation happens and the bromide ions become bromine gas.