What volume of hydrogen gas at STP may be prepared by the reaction of 7.62 g gallium (Ga) with an excess of hydrochloric acid (HCl)? Use the following reaction

Question

I need help solving this question. The reaction is 2 Ga (s) + 6 HCl (aq) ⟶ 2 GaCl3 (aq) ­+ 3 H2 (g)

Answer 1

2 Ga (s) + 6 HCl (aq) ⟶ 2 GaCl3 (aq) ­+ 3 H2 (g)  Balanced equation

Always be sure to start with a correctly balanced equation.

 

moles Ga = 7.62 g Ga x 1 mole/69.72 g = 0.0957 moles Ga

From balanced equation, 2 moles Ga = 3 moles H2, therefore...

Moles H2 formed = 0.0957 moles Ga x 3 moles H2/2 moles Ga = 0.1456 moles H2 formed

Volume H2 at STP = 0.1456 moles H2 x 22.4 liters/mole = 3.26 liters H2