Question

2H2(g)+O2(g)→2H2O(g) how many moles of O2 are required to react with 3.9 mol of H2 ?

Answer 1

Step 1

The reaction must be written and balanced:

2H2(g) + O2(g) → 2H2O(g)

(Numbers next to the chemical formulas in bold mean number of moles)

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Step 2

Procedure:

2 x 1 mole H2 -------- 1 mole O2

3.9 moles H2 -------- X

X = (3.9 moles H2 x 1 mole O2)/2 x 1 mole H2 = 1.95 moles O2

Answer: 1.95 moles O2