The molar volume (in units of litres per mole) is the same for all gases at the same temperature and pressure - Scottish Highers Chemistry - Question 10 - 2018

To measure the molar volume of gases, one could conduct an experiment involving a reaction between an acid and a metal, such as using hydrochloric acid and zinc. Here's a step-by-step guide:

1. Reacting the Metal with Acid: Place a known quantity of zinc in a flask and add hydrochloric acid. This reaction produces hydrogen gas:

   $Zn + 2HCl \rightarrow ZnCl_2 + H_2$

   This reaction generates hydrogen, and the moles of hydrogen produced can be measured.

2. Collecting the Gas: Use a gas syringe or an inverted measuring cylinder filled with water to collect the hydrogen gas produced. This method allows for the accurate measurement of the gas volume.

3. Recording the Volume: Record the volume of hydrogen gas at room temperature and pressure once the reaction has completed.

4. Calculating Moles of Gas: Using the ideal gas law, you can relate the volume of the gas collected to the number of moles. The molar volume (in L/mol) can be calculated using:

   $PV = nRT$ or rearranging gives $n = \frac{PV}{RT}$ where P is the pressure, V is the volume, R is the gas constant, and T is the temperature in Kelvin.

5. Comparing Molar Volumes: Repeat the experiment with different gases, such as hydrogen and carbon dioxide, and compare their molar volumes collected under the same conditions of temperature and pressure.

Using this method, one can effectively measure and compare the molar volumes of different gases.