Electrolysis of Aqueous Solution
- An aqueous solution is solution of water of a substance. For example, if you heat sodium chloride until it melts, it is called molten sodium chloride, but if you dissolve sodium chloride in water, it is called aqueous sodium chloride.
- Electrolysis of aqueous solution is different from electrolysis of molten electrolyte because an aqueous solution contain more types of ions.
Ions presence in molten sodium chloride are Na+ and Cl–
NaCl –> Na+ + Cl–
Ions presence in sodium chloride solution are Na+, H+, O2-and Cl–
In an aqueous solution, it can be more than 1 positive and negative ions.
- When the ions move to the anode and cathode, only 1 negative ion and 1 positive ion will be selected to be discharged, and this is called selective discharge.
- There are three main factors that affect the selective discharge in electrolysis:
- position in the electrochemical series
- the concentration and
- the type of electrode