The Molar Volume of Gas Mg(s) + 2 HCl (aq) = H2 (g) + MgCl2 (aq)

Trial 1 Trial 2

1. Weight of Mg ribbon 0.0342 g ___0.0350 g

2. Moles of Mg 0.00141 ? mole 0.00144 ? mole

3. Moles of H2 0.00141? mole 0.00144? mole

4. Temperature of H2O 21.2 °C 21.2 °C (assume it’s after temp equalization)

5. Barometric pressure mmHg mmHg (assume this to be 1.00 atm)

6. Volume of Hydrogen 26.5 mL 37.4 mL

7. Vapor pressure of H2O mmHg mmHg

8. Pressure of dry H2 mmHg mmHg

9. Volume of dry H2 at STP L L (show your work below)

10. Molar Volume of H2 at STP (V0) L/mol L/mol

11. Average Molar Volume of H2 L/mol

12. Percent deviation % %

In the space below, show your work, including units, for finding the molar volume of dry H2 at STP.

Trial 1: Trial 2:

1) After the reaction was complete it was necessary to equalize the pressures between the room and the tube. Before the pressures were equalized, assume that the level of the gas in the tube was above the level of the water in the smaller jar (before transferring to the large tank to equalize the pressure). In this case, which was at a higher pressure, the lab room, or the gases in the collection tube?

2) After the reaction was completed, it was necessary to wait ~ 5 minutes before measuring the gas volume in order to equalize the temperatures between the tube and the water.

A. Why was it important to wait rather than collect data immediately after the reaction ended? Give specific reason(s).

B. If you hadn’t waited, would your molar volume result be too large or too small? Explain.

3) We know the accepted value of molar volume at STP and now we have two experimentally determined molar volume values, plus their calculated average. These numbers are: Vo, accepted = Vo, trial 1 = Vo, trial 2 = Vo, avg =

A. Comparison of which two of the four values above can be used to indicate the accuracy of these experimental results?

B. Comparison of which two of the four values above best indicates the precision of the experimental results?