Equipment:

- Data collection system

- Stainless steel temperature sensor

- Erlenmeyer flask, 250-mL

- Beaker, 400-mL

- Test tube, 20-mL

- Copper wire coil

- Ring stand

- Hotplate

- Stirring bar

- Clamp (2), utility

- Lauric acid, CH3(CH2)10COOH, 8 g

- Unknown solute, 1.00 g

- Water, 300 mL

Safety:

1. Handle the hot water bath carefully while mounting and removing the test tube

2. Upon completion, wash all equipment properly with the assigned solvent for cleaning

Method:

1. Carefully transfer the solvent into the test tube

Important: Make sure there is no loss of the sample when doing a transfer

2. Turn on the hotplate and the stirring bar

3. When the crystals melt, place the stainless steel sensor with the copper coil wrapped around it into the melted crystals

Note: Observe the white deposit on the surface of the sensor

4. Once the test tube is clear (the crystals are melted), remove the test tube from the water bath, with the sensor and coil still in it, and clamp it in the empty Erlenmeyer flask

Important: Do not stop stirring while collecting data. Even a few seconds without stirring can affect your graph

5. Start recording data and start stirring the contents of the test tube by moving the copper coil up and down

6. Adjust the scale of the graph

7. Once the contents of the test tube are completely solidified, stop data recording

8. Mount the test tube into the water bath again and allow the contents of the test tube to melt

9. Measure about 0.5 g of the unknown sample to the nearest 0.01 g and record the mass in Table 1

10. Carefully transfer the solute into the test tube

Important: Make sure there is no loss of the sample when making the transfer

11. Once the test tube is clear (the crystals are melted), remove the test tube from the water bath, with the sensor and coil still in it, and clamp it in the empty Erlenmeyer flask

Important: Do not stop stirring while collecting data. Even a few seconds without stirring can affect your graph.

12. Start the data recording and start stirring the contents of the test tube by moving the copper coil up and down

13. Once the contents of the test tube are completely solidified, stop data recording

14. Display both data runs in the graph

15. From the curves, locate the freezing points of the pure solvent and the solution. Record these in Table 1.

16. Print the graph

17. Melt the contents of the test tube again and dispose of the chemicals into the designated waste container

18. Save your experiment and clean up according to your teacher's instructions