The number of moles of oxygen in 1 L of air containing 21 % oxygen by volume, under standard conditions, is

Question

The number of moles of oxygen in 1 L of air containing 21 % oxygen by volume, under standard conditions, is (A) 0.0093 mole (B) 2.10 moles (C) 0.186 mole (D) 0.21 mole

Tardigrade Admin · Accepted Answer

Volume of oxygen in 1 L of air (21/100) × 1000=210 mL ∴ 22400 mL volume at STP is occupied by oxygen =1 mole Therefore, number of moles occupied by 210 mL (210/22400) =0.0093 mol

Q. The number of moles of oxygen in $1 L$ of air containing $21%$ oxygen by volume, under standard conditions, is

0.0093 mole

2.10 moles

0.186 mole

0.21 mole

Volume of oxygen in $1 L$ of air
$\frac{21}{100} \times 1000 = 210 m L$
$∴ 22400 m L$ volume at STP is occupied by oxygen $= 1$ mole
Therefore, number of moles occupied by $210 m L$
$\frac{210}{22400}$
$= 0.0093 m o l$

Q. The number of moles of oxygen in 1L of air containing 21% oxygen by volume, under standard conditions, is