Alex T. ZhaoGreg KerrIB Chemistry HLNovember 12, 2012

Molar Volume of Hydrogen GasPurpose:

In this experiment the volume of hydrogen gas that is produced when a small piece of magnesium reacts with hydrochloric acid is measured. The volume of hydrogen gas will be measured at room temperature and pressure, and the molar volume of hydrogen under standard conditions of temperature and pressure will be calculated.

Equipment: Coil of copper wire (about 10 cm) Hydrochloric acid [HCL] 3M (15mL) Gas measuring tube or burette (50 mL). One-hole stopper to fit the gas measuring tube Magnesium ribbon (about 3 cm) Stand and clamp Graduated cylinder (250 mL) Thermometer (-10—110C) Barometer Beaker (500m mL) Ruler

Procedure: See attached sheet

Data Collection: Criteria ValueLength of Magnesium ribbon 3.10 ± 0.05cmMass of 50 cm Mg ribbon 0.90 ± 0.05gRoom Temperature 296 ± 1KPressure 102.03 ± 0.05kPaVapor Pressure 2.81± 0.05kPaVolume of hydrogen: 0.057 ± 0.005dm3

Processing of results, and questions1. Mass of Magnesium used:

Hence the mass of magnesium used is 0.0558gramsNumber of mols of Magnesium:

2. Calculating the pressure of H2

IB Chemistry HL Lab 5 Nov 12, 2012

3. Calculating what volume Hydrogen gas will occupy at STP:

Volume of Hydrogen gas at STP is 0.051dm3

4. Calculating the volume if used 1 mole of magnesium

Volume of 1 mol of Hydrogen gas at STP is 22.4dm3

5. Equation of reaction:

For each mol of Magnesium, 1 mol of hydrogen gas is formed, or in other words, 2 mols of hydrogen atoms are formed.

6. From questions 4 and 5, we calculate the molar volume of hydrogen at STP to be 22.4dm3. This is identical to the established value of the molar volume of an ideal gas at STP.

7. In this experiment, we assumed that hydrogen gas is not soluble in water at atmospheric pressure. This assumes that all the hydrogen produced is captured in the tube. If hydrogen gas was soluble in water, then our calculated molar volume of hydrogen gas at STP will be inaccurate.

8. If we used sulfuric acid instead of hydrochloric acid, then the equation would be:

From this equation, we see that each mol of Mg still yields 1 mol of hydrogen gas. Hence, there will not have been any observable differences in the final result.

IB Chemistry HL Lab 5 Nov 12, 2012