Figuring out Mole equations

Question

How many grams of hydrogen are needed to produce 1.80 g of water according to this equation? 2H2+ O2→2H2O

Answer 1

Hey there!

Always start with what you're given and then convert from there.

1.8 g H2O * ( 1 mol H2O / 18 g H2O) = 0.1 mol H2O (You find this using the periodic table)

Now convert using the equation, which gives mole to mol ratios:

0.1 mol H2O * (2 mol H2 / 2 mol H2O) = 0.1 mol H2

Now convert back to grams using the periodic table:

0.1 mol H2 * (2 g H2 / 1 mol H2) = 0.2 g H2