1a. Define the term stoichiometric coefficient.

b. Balance these equations.

(i) Al(s) + O2(g) Al2O3(s)

(ii) N2(g) + H2(g) NH3(g)

(iii) C6H6(l) + O2(g) : H2O(l) + CO2(g)

(iv) CaC2(s) + H2O(l) Ca(OH)2(s) + C2H2(g)

(v) (NH4)2Cr2O7(s) Cr2O3(s) + N2(g) + H2O(g)

(vi) CH3NH2(g) + O2(g) CO2(g) + N2(g) + H2O(g)