Question

How much H is need to react with 6.58 g of O, in this reaction?
H2 + O2 -> H2O

Answer 1

Balance the equation first

`2H_(2) \ + \ O_(2) \ --> \ 2H_(2)O`

6.58g of Oxygen gas

Divide 6.58g by molar mass of oxygen (32g/mol)

6.58/32 = 0.205625 mol

Use mol to mol ratio from looking at the coefficients of the reactants, the mol ratio of Hydrogen gas to Oxygen gas is 2:1, so for every 1 mol of Oxygen, you need 2 times the mol of hydrogen for it to make water.

0.205625 * 2 = 0.41125 mol

To get the mass of hydrogen gas needed in the reaction, turn 0.41125 mol into mass by multiplying it with Hydrogen gas's molar mass, which is 2.02 g/mol.

0.41125 * 2.02 ≈ 0.83g of H2