Solution of problem 624 of the collection on general ch

Solution of problem 624 of the collection on general ch

624. Write the equations for the half reactions of oxidation and reduction for the following reactions and determine in which cases hydrogen serves as an oxidizer and in which as a reducing agent:

A) 2Al + 6HCl = 2AlCl3 + 3H2

B) 2H2 + O2 = 2H2O

C) 2Na + 2H2O = NaOH + H2

D) BaH2 + 2H2O = Ba (OH) 2 + 2H2