What Is an Example of a Lab for Finding the Molar Volume of a Gas?

An example of a lab for finding the molar volume of a gas involves using the reaction Mg(s) + 2HCl(aq) --> MgCl2(aq) + H2(g) to find the molar volume of hydrogen gas. The lab measures the hydrogen gas produced during the reaction through displacing water, the volume of which is then computed. The lab assumes conditions of standard temperature and pressure.

Another example of a lab for finding the molar volume of a gas uses the reaction 2KClO3(s) --> 2KCl(s) + 3O2(g), in which potassium chlorate is heated to a point where it decomposes and produces gaseous oxygen. The properly measured reaction produces known mass of oxygen gas, which can then be used to measure temperature, volume and pressure. Those values are necessary to calculate the molar volume of the oxygen with the formula V = RT/P, where V is the volume at standard temperature and pressure conditions divided by the moles of oxygen.

Equipment needed for these labs include a 1,000-milliliter flask, a 600-milliliter beaker, rubber tubing and a Bunsen burner. The pressure in the flask is determined by adding together the partial pressures of the water vapor and the oxygen. The lab requires two trials to ensure accuracy.