Lab 19 – Molar Volume of a Gas
Due Date: February 23, 2009
1) Obtain a piece of magnesium ribbon from you teacher. Find the mass of the ribbon and record in the data table.
2) Obtain a piece of thread about 15 cm long. Tie one end of the thread around the piece of magnesium ribbon, leaving about 10 cm of thread free. Bend the ribbon so that it will easily fit into the gas-measuring tube as shown in figure 1.
3) CAUTION: HANDLE ACIDS WITH CARE! Obtain about 10mL of 3M HCl. Carefully pour the HCl into the gas-measuring tube
4) Tilt the gas-measuring tube slightly. Using the 100 mL beaker of water, slowly fill the gas-measuring tube with water. Try to avoid mixing the acid and water as much as possible.
5) Lower the piece of magnesium ribbon 4 or 5 cm into the gas-measuring tube. Drape the thread over the edge of the tube and insert the one-hole stopper into the tube to hold the thread in place as shown in figure 2.
6) Place the 400 mL beaker of water in the position shown in figure 3.
7) Place your finger over the hole in the rubber stopper and invert the gas-measuring tube. Lower the stoppered end of the tube into the 400 mL beaker of water. Clamp the tube in place so that the stoppered end is a few cm above the bottom of the beaker as shown in figure 3. Record your visual observations under the date table.
8) Let the apparatus stand about five minutes after the magnesium has completely reacted. Then tap the sides of the tube to dislodge any gas bubbles that may have become attached to the sides of the tube. Place your finger over the hole in the stopper and transfer the tube to the 1000 mL beaker of water. Lower the end the tube in the water and remove you finger from the hole.
9) Move the tube up or down (to equalize pressure) until the water level in the tube is at the same height as the water level in the 1000 mL beaker. On the scale of the gas-measuring tube, read the volume of the gas in the tube. Record this volume in...