Calculations involving the volume of a gas are simpler than those involving a solid or a liquid because of a discovery made by the Italian chemist Amedeo Avogadro in 1811. Avogadro hypothesized that the volume of a gas depends only on the number of moles of the gas, regardless of the type of gas. Under equal conditions, the same number of moles of all gases have the same volume. Standard molar volume is the volume occupied by one mole of an ideal gas at STP (standard temperature and pressure), equal to 22.4 liters (L). The standard temperature is 273.15 kelvin (K), and the standard pressure is 1 atm.The relationship among the moles of a gas, the volume of the gas in liters, and the molar volume is similar to the mass-to-mass formula.
1. Write the balanced chemical equation for the reaction.
2. Determine the number of moles of the reactants.
3. Calculate the number of moles of the products.
4. Convert the moles of the products into volume.
Equations involving gases may be in volumes on both sides. In such cases, the steps to be followed are:
1. Write the balanced chemical equation.
2. Use the molar mass of a gas to convert moles to volume in liters.
3. Use the mole ratio to convert the number of moles of the products.
4. Use the molar volume to convert moles of the product to liters.