# Molar Volume Of a Gas Lab

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Molar Volume of a Gas PRE-LAB DISCUSSION Avogadro’s hypothesis states that equal volumes of all gases contain equal numbers of molecules under the same conditions of temperature and pressure. It follows from this hypothesis that all gas samples containing the same number of molecules will occupy the same volume under the same conditions of temperature and pressure. A special name is given to the volume occupied by 1-mole samples of gases at STP. This volume is called the molar volume. In this experiment, you will make an experimental determination of the molar volume. The basis of this experiment is the following reaction in which you will react a known mass of magnesium with excess hydrochloric acid to produce the substances shown: Mg(s) + 2HCl(aq) ( MgCl2(aq) + H2 (g) The hydrogen gas is the product that is of interest to you in this experiment. You will make an experimental determination of the number of moles of hydrogen molecules produced and the volume occupied by these molecules. The number of moles of hydrogen will be determined indirectly. The balanced equations for this reaction shows that the molar ratio of magnesium reacted to hydrogen gas produced is 1:1. Therefore, by determining the mass of magnesium that reacts and the number of moles that this mass is equal to, you will also be able to determine the number of moles of hydrogen gas produced. The volume of hydrogen gas produced will be measured directly on the scale of a gas-measuring tube. The gas laws of Boyle and Charles will be used to correct this volume, measured under laboratory conditions, to the volume the sample of gas would occupy at STP. The collected data (number of moles and volumes at STP) will be used to calculate that molar volume of the hydrogen gas. This experiment should aid in the understanding of the mole concept and the concepts of molar volume of a gas.