Volumes of Gases [Chemistry only, Higher Tier]

Molar volume

• Equal amounts in moles of any gases occupy the same volume at the same temperature and pressure
• At room temperature and pressure (20 °C and 1 atmosphere) one mole of any gas occupies 24 dm³, which is 24 000 cm³

$$\text{volume (dm}^3) = \text{moles} \times 24 \qquad \text{moles} = \frac{\text{volume (dm}^3)}{24}$$

• Worked example: volume of 0.5 mol of hydrogen at rtp: $0.5 \times 24 = 12$ dm³
• From a mass: moles first. 8 g of oxygen ($M_r = 32$) is 0.25 mol, so $0.25 \times 24 = 6$ dm³