Electrolysis of aqueous solutions Flashcards
What are the products of electrolysis with brine?
1) Chlorine gas is produced at the anode
2) Hydrogen gas is produced at the cathode
3) Sodium hydroxide solution is formed
What happens at the positive electrode when using electrolysis on brine?
The negative chloride ions are attracted to the positive electrode. When they get there they each lose one electron. The chlorine atoms bond together in pairs and are given off as chlorine gas, Cl2
What happens at the negative electrode when using electrolysis on brine?
H+ ions are attracted to the negative electrode. The sodium ions, are also also attracted to the same electrode. Hydrogen ions are discharged and sodium ions stay in solution as aqueous ions.
When H+ ions reach the negative electrode, they each gain one electron. The hydrogen atoms formed bond together in pairs and are given off as hydrogen gas. H2
How can you test the remaining solution around the cathode? (brine)
With an acid/base indicator. It shows that the solution is alkaline. This is because the Cl- ions and H+ ions are removed during electrolysis. So this leaves a solution containing Na+ and OH- (aq) which is a solution of alkaline sodium hydroxide.
