Question

Water can be formed according to the equation: 2h2 (g) + o2 (g) → 2h2o (g) if 8.0 l of hydrogen is reacted at stp, exactly how many liters of oxygen at stp would be needed to allow complete reaction?

Answer 1

Four litre of oxygen will be required

Answer 2

Answer:

3.99  liters of oxygen at STP would be needed to allow complete reaction.

Explanation:

$2H_2+2O_2\rightarrow 2H_2O$

At STP, 1 mol of gas occupies = 22.4 L

Then 1 Liter of volume will be occupied by:

$1 L=\frac{1}{22.4 } mol$

The 8 Liter of volume will be occupied by:

$\frac{1}{22.4 }\times 8 mol=0.3571 mol$

Moles of hydrogen gas = 0.3571 mol

According to reaction, 2 moles of hydrogen gas reacts with 1 mol of oxygen gas.

Then 0.3571 moles of hydrogen gas will react with:

$\frac{1}{2}\times 0.3571 mol=0.1785 mol$ of oxygen

Moles of oxygen required to react completely = 0.1785 moles

At STP, 1 mol of gas occupies = 22.4 L

Then 0.1785 moles of oxygen will occupy:

$0.1785 moles\times 22.4 L = 3.99 L$

3.99  liters of oxygen at STP would be needed to allow complete reaction.