According to the equation 2Na + 2H2O mc012-1.jpg 2NaOH+H2, what mass of Na is required to yield 22.4 L of H2 at STP? (The atomic mass of Na is 22.99 u.)

a.1.00 g
b.2.00 g
c.23.0 g
d.46.0 g

Question

According to the equation 2Na + 2H2O mc012-1.jpg 2NaOH+H2, what mass of Na is required to yield 22.4 L of H2 at STP? (The atomic mass of Na is 22.99 u.)

a.1.00 g
b.2.00 g
c.23.0 g
d.46.0 g

cuanchi · Answer

2Na + 2H2O -> 2NaOH+H2

22.4L is the molar volume of one mole of any gas at STP conditions. From the stoichiometry of the reaction you can see that 2 moles of Na will produce one mol of H2. Then if you have to produce one mole of H2 you will need 2 moles of Na. The problem also said that the atomic mass of Na is 23.99 g/mol.
If you need 2 mol of Na, then 23.99g x 2 = ?