Lab Experiment 1 - Generating hydrogen gas - for online class PDF

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Lab experiment, is one of the many lab exercises. It shows what we are required to do during lab and what we should be focusing on during the lab....

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Generating Hydrogen Gas Objectives 1. To determine the experimental molar volume of hydrogen gas at STP 2. To learn how to collect a gas over water 3. To learn how to read a barometer Procedure Part A 1. Cut a strip of Mg of mass between 0.07 and 0.09 g. Record its mass. Roll it into a coil and wrap it with a copper strip. 2. Fill a 1 L beaker with about 700 mL water and drop the copper-wrapped magnesium into the water. 3. Fill a 100 mL graduated cylinder with water up to the rim. 4. Place a small filter paper over the rim and allow it to absorb water. 5. Invert the cylinder and carefully put it into the 1 L beaker. (Be careful not to lose any water during the inversion.) As the filter paper floats free, place the mouth of the cylinder over the copper-wrapped magnesium. The cylinder is now at an angle leaning against the inner wall of the beaker. 6. Add 25 mL dilute HCl into the beaker using a long-stem filter funnel. Gas bubbles are observed when the acid reacts with magnesium. 7. When the reaction is complete, tilt the cylinder vertically and record the volume of the gas collected. 8. Place a thermometer into the beaker and observe the temperature. Since the hydrogen gas is collected over water, the temperature of hydrogen gas is the same as the temperature of the water in the beaker. 9. Record the atmospheric pressure using the barometer. 10. Find the vapor pressure of water from the data in Table 1. 11. Calculate the molar volume of hydrogen at STP. Table 1: Vapor pressure of water Temperature, °C 16 17 18 19 20

Pressure, mm Hg 14 15 16 17 18

Temperature, °C 21 22 23 24 25

Pressure, mm Hg 19 20 21 22 23

Temperature, °C 26 27 28 29 30

Pressure, mm Hg 25 27 28 30 32

Data for this experiment A sample of 0.0750 g Mg reacts with HCl acid to produce 77.5 mL hydrogen gas. The ‘wet’ gas is collected over water at 20° C and at an atmospheric pressure of 763 mmHg. Calculate the experimental molar volume of hydrogen gas at STP.

Prepared by Chandra Nanthakumar / Generating Hydrogen Gas

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