chemistry lab

Unit 7 Lab: Liquids and Solids

CHEM 1806

Purpose: To measure boiling and melting points

Materials: Student Supplied –spoon, isopropyl alcohol, rubber bands, white paper

LabPaq materials: 100mL glass beaker, burner fuel, burner stand, gloves, test tubes, thermometer, Liquids and Solids experiment bag

Procedure:

Boiling point

1. Place approximately 1mL of isopropyl alcohol in a test tube.

2. Attach a thermometer to the outside of the test tube with a small rubber band. The thermometer bulb should be even with the test tube’s bottom.

3. Insert an inverted closed – end capillary tube into the test tube. (open side down in the liquid)

4. Put approximately 50mL of warm tap water in the beaker.

5. Place the test tube assembly into the water bath so that the surface level of the alcohol is beneath the surface level of the water.

6. Place the beaker on the burner stand and the burner under the stand.

7. Light the fuel.

8. Stir the water bath frequently to ensure even heating until the water bath boils and a rapid stream of bubbles emerges from the capillary tube.

9. Extinguish the burner by setting the cap over the flame.

10. When the last bubble emerges from the capillary tube, record the temperature as the boiling point of isopropyl alcohol.

Melting point

1. While wearing gloves, insert powdered acetamide into the open end of new capillary tube by gently pushing and tapping the capillary tube into the powder. **I had to put some acetamide on a paper towel, cover with another paper towel, and crush with a meat hammer. That way the powder goes in the tube MUCH easier.

2. Flip the capillary tube over and gently tap the closed end on the counter to move the solid towards the closed end. It is easier than it sounds.

3. Repeat 1 & 2 until there is approximately 2 mm of powder in the tube that is in the last quarter of the tube towards the closed end.

4. Carefully attach the filled capillary tube to a thermometer with a rubber band and align the bulb with the bottom of the capillary tube.

5. Prepare a water bath as with the previous procedure.

6. Place the capillary tube assembly in the water bath and heat until the acetamide melts. Extinguish the burner flame.

7. Let the acetamide cool and re-crystallize. Record the temperature that recrystallization occurs.

Dispose of the capillary tubes by wrapping them in paper and place them in the trash. Excess acetamide and isopropyl alcohol can be flushed down the drain.

(3 pts)Discuss potential errors in your experiment. (Use complete sentences.)

(3 pts) The published boiling point of isopropyl alcohol is 82.4 C. The published melting point of acetamide is 81 What is the percent error in your measurements?

(9 pts) Insert a picture of your lab set up.

When you have finished, please save the file as LASTNAME_Liquids and upload to the Unit 7 Lab dropbox.