Question

What volume is occupied by 0.25 grams of oxygen gas measured at 25.0 deg C

and 100.66 kPa? ( 5 marks)

  ( universal gas constant= 8.314 Kpa. L mol^-1 K^-1)

Answer 1

p = 100.66 kPa

T = 25 + 273 = 298 K

M(O₂) = 32 g/mol

m = 0.25 g

$n = \frac{m}{M} \\ n(O_2) = \frac{0.25}{32} = 0.0078 \;mol$

Ideal Gas Law

$pV = nRT \\ V = \frac{nRT}{p} \\ = \frac{0.0078 \times 8.314 \times 298}{100.66} \\ = 0.192 \;L$

Answer: 192 mL