Answer Happy

Procedure 1. Start Virtual ChemLab, select Colligative Properties, and then select Molar Mass Determination by Freezing Point Depression from the list of assignments. The lab will open in the Calorimetry laboratory with a beaker containing 45.00 g of ice and a coffee cup calorimeter on the lab bench. A sample of of an unknown solid will also be on the balance. 2. Click on the Lab Book to open it. Record the mass of the solid in the data table. If it is too small to read, click on the Balance area to zoom in, record the mass, and then return to the laboratory. 3. 100 mL of water is already in the calorimeter. Use the density of water at 25°C (0.998 g/mL) to determine the mass from the volume and record it in the data table. Make certain the stirrer is On (you should be able to see the shaft rotating). IN the thermometer window, click Save to begin recording data in the lab book. Allow 20-30 seconds to obtain a baseline temperature of the water. Click the clock on the wall labeled Accelerate to accelerate the laboratory time if necessary. 4. Drag the beaker of ice until it snaps into place above the calorimeter and then pour the ice into the calorimeter. Click the thermometer and graph windows to bring them to the front and observe the change in temperature in the graph window until it reaches zero. Drag the weigh paper from the balance to the calorimeter and then pour it into the calorimeter. Observe the change in temperature until it reaches a stable minimum and click Stop in the temperature window. A data link icon will appear in the lab book. Click the data link icon and record the lowest temperature after adding the salt in the data table. (Remember that the water may have begun to warm back up.) 5. To repeat the experiment, click on the red disposal bucket to clear the lab, click on the Stockroom, click on the clipboard, and select Preset Experiment #1, Freezing Point Depression - NaCl. Data Table Trial 1 Trial 2 mass solid mass water mass ice mass water + ice minimum temperature