Boiling Point Elevation
4-4 Boiling Point Elevation
If you dissolve a substance such as ordinary table salt (NaCl) in water, the boiling point of the water will increase relative to the boiling point of the pure water. In this assignment, you will dissolve a sample of NaCl in water and then measure the boiling point elevation for the solution.
1. Start Virtual ChemLab and select Boiling Point Elevation from the list of assignments. The lab will open in the Calorimetry laboratory with a calorimeter on the lab bench and a sample of sodium chloride (NaCl) on the balance.
2. Record the mass of the sodium chloride in the data table. If it is too small to read, click on the Balance area to zoom in, record the reading, and then
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1. Start Virtual ChemLab and select Boyle’s Law: Pressure and Volume from the list of assignments. The lab will open in the Gases laboratory. 2. Note that the balloon in the chamber is filled with 0.300 moles of an ideal gas (MW = 4 g/mol) at a temperature of 298 K, a pressure of 1.00 atm, and a volume of 7.336 L. To the left of the Pressure LCD controller is a lever that will decrease and increase the pressure as it is moved up or down; the digit changes depending on how far the lever is moved. Digits may also be clicked directly to type in the desired number. You may want to practice adjusting the lever so that you can decrease and increase the pressure accurately. Make sure the moles, temperature, and pressure are returned to their original values before proceeding. 3. Click on the Lab Book to open it. Back in the laboratory, click on the Save button to start recording P, V, T, and n data to the lab book. Increase the pressure from 1 atm to 10 atm one atmosphere at a time. Click Stop to stop recording data, and a blue data link will appear in the lab book. To help keep track of your data links, enter ‘Ideal Gas 1’ next to the link. 4. Zoom Out by clicking the green arrow next to the Save button. Click Return Tank on the gas cylinder. On the table underneath the experimental chamber is a switch to choose Real gases or Ideal gases. Click on the Ideal Gases and choose the cylinder