The following half-reactions are joined to form a galvanic cell that generates a current under standard conditions. Identify what is oxidized and what is reduced. Write a shorthand cell diagram, and calculate the standard cell potential (E°).
2 H+(aq) + 2 e- → H2(g) and Ni2+(aq) + 2 e- → Ni(s)

Reacting masses1 calcium carbonate breaks down on heating to produce calcium oxide and carbondioxide gas.caco3 + cao + co2a student heats 15 g of calcium carbonate strongly in a crucible.relative atomic masses (a): ca = 40, c = 12, o = 16.calculate the mass of calcium oxide produced by this reaction.(5 marks)