Specification Point 1.35 (Paper 2C Only):
Understand how to carry out calculations involving Gas Volumes and the Molar Volume of a Gas ( 24 dm3 and 24 000 cm3 at room temperature and pressure (rtp))

Volume of one mole of any gas is molar volume. It is 24dm3 or 24000 cm3 at R.T.P.

Calculations Involving Gases

General Equation:

Equation for amount of gas, Edexcel IGCSE Chemistry

Calculating Volume

Equation:

Volume of Gas ( dm3 )      =      Amount of Gas ( mol )     x    24

OR             

Volume of Gas ( cm3 )      =     Amount of Gas ( mol )     x    24000

Example:

Name of gas Amount of gas Volume of gas
Hydrogen 3 mol ( 3 x 24 ) = 72 dm3
Carbon Dioxide 0.25 mol ( 0.25 x 24 ) = 6 dm3
Oxygen 5.4 mol ( 5.4 x 24000 ) = 129600 cm3
Ammonia 0.02 mol ( 0.02 x 24 ) = 0.48 dm3

Calculating Moles

Equation:

Equation for amount of gas, Edexcel IGCSE Chemistry

Example:

Name of gas Volume of gas Moles of gas
Methane 225.6 dm3 ( 225.6 ÷ 24 ) = 9.4 mol
Carbon Monoxide 7.2 dm3 ( 7.2 ÷ 24 ) = 0.3 mol
Sulfur Dioxide 960 dm3 ( 960 ÷ 24 ) = 40 mol
Oxygen 1200 cm3 ( 1200 ÷ 24000 ) = 0.05 mol

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.