Stoichiometry Gas Problem

Question

Sodium reacts vigorously with water to produce hydrogen and sodium hydroxide 2Na(s) + 2H2O(i) -> 2NaOH(aq) + H2(g). If 0.027 g of sodium react with excess water, what volume of hydrogen at STP is formed?

Answer 1

2Na(s) + 2H₂O(l) ==> 2NaOH(aq) + H₂(g) ... balanced equation

0.027g......xs........................................?.........

moles Na used = 0.027 g x 1 mol Na/23 g = 0.00117 moles Na

moles H₂ produced = 0.00117 mol Na x 1 mol H₂ / 2 mol Na = 0.000587 moles H₂ formed

At STP 1 mol of an idea gas = 22.4 L

Volume H₂ formed = 0000587 mol x 22.4 L/mole = 0.0131 L = 0.013 L (2 significant figures)