Question

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.)

Answer 1

46.0g Na

Since 22.4L of anything at STP is one mole, you can use your mole fraction to easily determine the # of moles of Na to produce one mole of H2. In this case, 2 moles of Na yield 1 mole H2, so all you need to do now is convert to grams. (Moles x Molar mass) which is 2 moles Na X 23g . this gives you the answer of 46g of Na.