Question

Begin by writing formulas for the reactants and products, including physical states. When necessary use coefficients to balance the equation

(a) When solid sodium hydride, NaH, is added to water, hydrogen gas is released and
    aqueous sodium hydroxide forms.

   

AP 1

   (b) Aluminum metal reacts with chlorine gas to form solid aluminum chloride.

Answer 1

A)

formulas of the reactents and products

NaH (s) + H2O (aq) -------> NaOH (aq) + H2 (g)

both sides 1 Na

both sides 3H and

both sides one O

so no meed to balance this reaction this waas already balanced

b)

formulas of the reactents and products

Al (s) + Cl2 (g) -----> AlCl3

right side 3Cl are there but left side only two

so multiply right side with 2 and left side with 3

Al (s) + 3Cl2 (g) -----> 2AlCl3   now both sides 6Cl

now comming to Al

right side has 2 Al and left side have 1 Al

so multiply left side with 2 and right side with 1

so

2Al (s) + 3Cl2 (g) -----> 2AlCl3 this is the complete balanced reaction