Question

Sodium and water react according to the following equation. If 31.5g of sodium are added to excess water, how many liters of hydrogen gas are formed at STP? Show all work for credit.

2Na + 2H2O 2NaOH + H2

Answer 1

first step: calculate the number of moles of sodium reacted
moles=mass/molar mass
31.5g/23g/mol =1.37moles
from the reaction above the reacting ratio of Na to H2 is 2:1 therefore moles of H2 is 1.37/2=0.685
At STP 1 mole = 22.4L what about 0.685 moles
22.4 x0.685=15.344L