A student combines 5 g of sodium with 10 g of water and produces 8 grams of sodium hydroxide and hydrogen. How many grams of hydrogen gas are produced?

Answer 1

First, write the unbalanced chemical equation:

Na + H2O --> NaOH + H2

Then, balance the equation:

2Na + 2H2O --> 2NaOH + H2

We can now use the mass of NaOH produced to determine how much H2 is produced using dimensional analysis:

__g H2 = 8 g NaOH x 1 mol NaOH/ 39.99 g NaOH x 1 mol H2/2 mols NaOH x 2 g H2/1 mol H2 = 0.2 g H2