Relative atomic masses needed: Na = 23, Cl = 35.5, H = 1, Cu = 63.5, Al = 27, O = 16 and the molar volume of any gas is 24 dm3 at room temperature and pressure. The common electrode equations you may come across are listed below.
electrode involved: (-) negative cathode or (+) positive anode for the Electrode Equation below
moles of electrons involved (mass of product formed)
example of industrial process where this electrode reaction happens
sodium (-) Na+(l) + e- ==> Na(l)
1 (23g) = 1.0 mol Na metal per mol e-s
electrolysis of molten chloride salts to make chlorine and the metal
chlorine (+) 2Cl-(l/aq) - 2e- ==> Cl2(g)
2 (71g) = 0.5 mol Cl2 gas (12 dm3) released per mol e-s
electrolysis of molten chloride salts or their aqueous solution to make chlorine
hydrogen (-) 2H+(aq) + 2e- ==> H2(g)
2 (2g) = 0.5 mol H2 gas (12 dm3) released per mol e-s
electrolysis of many salt solutions to make hydrogen
copper (-) Cu2+(aq) + 2e- ==> Cu(s)
2 (63.5g) = 0.5 mol Cu deposited per mol e-s
deposition of copper in its electrolytic purification or electroplating
copper (+) Cu(s) - 2e- ==> Cu2+(aq)
2 (63.5g) = 0.5 mol Cu dissolves per mol e-s
dissolving of copper in its electrolytic purification or electroplating
aluminium (-) Al3+(l) + 3e- ==> Al(l)
3 (27g) = 0.33 mol Al metal per mol e-s
extraction of aluminium in the electrolysis of its molten oxide ore
oxygen (+) 2O2-(l) - 4e- ==> O2(g)
4 (32g) = 0.25 mol O2 (12 dm3) gas released per mol e-s electrolysis of molten oxides
oxygen (+) 4OH-(aq) - 4e- ==> 2H2O(l) + O2(g)
4 (32g) = 0.25 mol O2 gas (6 dm3) released per mol e-s electrolysis of many salt solutions such as sulphates, sulphuric acid etc. gives oxygen (but chloride salts ==> chlorine)
(Thats some formulas for different elements that are commenly used)
