Collegiative Properties and Osmosis
Department of Chemistry
[Colligative Properties & Osmotic Pressure]
Purpose :
The experiment this week had two different purposes. The first is to teach us about freezing points. This lab was designed to show us the freezing point of a pure solvent, in comparison to a solvent in a solution with a non-volatile solute. The second goal of the experiment is to teach students about osmosis. In the experiment, we got to observe osmosis as well as understand dialysis.
Procecure :
Part 1. Colligative Properties
1. Create a water bath by filling ½ of the 100 mL beaker with cool water, adding crushed ice to the beaker so the water level is just below the top, and sprinkling salt into the beaker and mixing
2. Half fill a test tube with distilled water and place in a 24 well plate. Insert thermometer into tube and take readings every 30 seconds until readings are constant
3. Place test tube into water bath and put stopwatch to zero, stir water in test tube with thermometer and record temperature every 30 seconds. Supercooling should occur.
4. Once five consecutive readings were made, remove tube and dump contents.
5. Refill half a test tube with room temperature distilled water and add 1/8 teaspoon of salt to the water in tube. Mix until dissolved
6. Repeat steps 1-4 with the salt water solution prepared in 5. Supercooling may not occur
7. Drain contents and put equipment away
8. Make two graphs, one with data of pure water one of data of salt water. Plot temperature on y axis and time on x axis
9. Once information is plotted. Draw the best straight lines for the regions
10. Extend lines until they intersect, which represent freezing points
Part 2. Osmotic Pressure
1. ½ fill a glass bowl with D water. Place dialysis tubing in it and completely submerge for 20-30 minutes.
2. After 20-30 minutes, remove from water and place on paper towel.
3. Pour water down drain and rinse bowl with D water, then fill halfway
[Colligative Properties & Osmotic Pressure]
Purpose :
The experiment this week had two different purposes. The first is to teach us about freezing points. This lab was designed to show us the freezing point of a pure solvent, in comparison to a solvent in a solution with a non-volatile solute. The second goal of the experiment is to teach students about osmosis. In the experiment, we got to observe osmosis as well as understand dialysis.
Procecure :
Part 1. Colligative Properties
1. Create a water bath by filling ½ of the 100 mL beaker with cool water, adding crushed ice to the beaker so the water level is just below the top, and sprinkling salt into the beaker and mixing
2. Half fill a test tube with distilled water and place in a 24 well plate. Insert thermometer into tube and take readings every 30 seconds until readings are constant
3. Place test tube into water bath and put stopwatch to zero, stir water in test tube with thermometer and record temperature every 30 seconds. Supercooling should occur.
4. Once five consecutive readings were made, remove tube and dump contents.
5. Refill half a test tube with room temperature distilled water and add 1/8 teaspoon of salt to the water in tube. Mix until dissolved
6. Repeat steps 1-4 with the salt water solution prepared in 5. Supercooling may not occur
7. Drain contents and put equipment away
8. Make two graphs, one with data of pure water one of data of salt water. Plot temperature on y axis and time on x axis
9. Once information is plotted. Draw the best straight lines for the regions
10. Extend lines until they intersect, which represent freezing points
Part 2. Osmotic Pressure
1. ½ fill a glass bowl with D water. Place dialysis tubing in it and completely submerge for 20-30 minutes.
2. After 20-30 minutes, remove from water and place on paper towel.
3. Pour water down drain and rinse bowl with D water, then fill halfway