Avogadro’s law is the basis for calculating the volume of gas produced in a reaction: equal volumes of gases at constant temperature and constant pressure contain the same number of molecules.
The volume occupied by 1 mole of a gas at a particular temperature and pressure is known as its molar volume.
- At standard temperature and pressure (273K, 101kPa) the molar volume is 22.4 dm3
- At room temperature and pressure (298K, 101kPa) the molar volume is 24.0 dm3
The key is to remember that when we are working with gases, it’s all about molar ratios, which makes calculations simple and logical 😊.
Practice questions
- What volume of carbon dioxide if produced when 6.0g of calcium carbonate react with excess hydrochloric acid at room temperature and pressure?
- What volume of oxygen is needed to completely react with 10.0 cm3 of hydrogen at room temperature and pressure?
- Calculate the volume of hydrogen produced when 1.4g of magnesium reacts with excess sulphuric acid.
Answers
