Molar gas volume - Higher
At a given temperature and Force exerted over an area. The greater the pressure, the greater the force exerted over the same area., one The amount of substance that contains the same number of particles as there are atoms in 12 g of carbon-12 (contains the Avogadro's constant 6.0 ×10²³ number of particles). of any gas occupies the same The volume of a three-dimensional shape is a measure of the amount of space or capacity it occupies, eg an average can of fizzy drink has a volume of 330 ml.:
- the The volume occupied by one mole of any gas (24 dm³ or 24000 cm³ at room temperature and pressure). is the volume occupied by one mole of any gas, at room temperature and pressure
The molar volume is equal to 24 dm3 (24,000 cm3). This volume is given in questions that need it.
Using the molar volume
Calculating the volume of a gas
The volume of a known In chemistry, a measure of the number of particles in a substance. of gas can be calculated:
Volume = amount in mol × molar volume
Question
Calculate the volume of 0.25 mol of hydrogen at room temperature and pressure. (Molar volume = 24 dm3)
volume = amount in mol × molar volume
volume = 0.25 × 24
= 6 dm3
Question
Calculate the volume of 0.10 mol of oxygen at room temperature and pressure. (Molar volume = 24,000 cm3)
Volume = amount in mol × molar volume
Volume = 0.10 × 24,000
= 2,400 cm3
Calculating the amount of a gas
The amount of a known volume of gas can be calculated:
Amount in mol = \(\frac{\textup{volume}}{\textup{molar~volume}} \)
Question
Calculate the amount of carbon dioxide that occupies 120 cm3 at room temperature and pressure. (Molar volume = 24,000 cm3)
Amount in mol = \(\frac{\textup{volume}}{\textup{molar~volume}} \)
Amount in mol = \(\frac{\textup{120}}{\textup{24,000}} \)
= 0.005 mol
Question
Calculate the amount of helium that occupies 36 dm3 at room temperature and pressure. (Molar volume = 24 dm3)
Amount in mol = \(\frac{\textup{volume}}{\textup{molar~volume}} \)
Amount in mol = \(\frac{\textup{36}}{\textup{24}}\)
= 1.5 mol