CHEM 180 DL1 Colligative Properties and Osmotic Pressure Lab Report

CHEM 180 DL1 Colligative Properties and Osmotic Pressure Lab Report

Chem 180-DL-1

Colligative Properties and Osmotic Pressure

In preparation in performing this activity, it enables me to;

• Explain the four colligative properties of a solution: vapor pressure lowering, freezing point depression, boiling point elevation, and osmotic pressure.
• Describe the process of osmosis and define osmotic pressure.
• Describe the mathematical relationship between osmotic pressure, molarity, and temperature.

In completing the activities, I should be able to;

• Observe and describe the process of osmosis through a semipermeable membrane.
• Determine the molecular mass of a compound using osmotic pressure data.
• Examine how the freezing and boiling points of solutions change as a result of the amount of solute present.

Procedure

1. Gather the bowl, distilled water, and the piece of dialysis tubing.
2. Soak the dialysis tubing for 5 minutes in a bowl filled with distilled water. Completely submerge it.
3. After the tubing has soaked 5 minutes, remove it from the water and put it on a paper towel.
4. Pour the water down the drain and rinse the bowl with distilled water. Refill the bowl halfway with distilled water.
5. To open the dialysis tubing, carefully rub the dialysis tubing between your fingers until the middle of the tubing opens.
6. Carefully close off 1 end of the dialysis tubing by folding the end and then tying it off using a cut rubber band. Test to make sure no leaks.
7. Insert the funnel into the open end of the dialysis tubing and hold the tubing snugly to the funnel during the next step.
8. Use the funnel to carefully fill the dialysis tubing one-third full with the light syrup.
9. Carefully push out most of the air that is inside the tubing above the lite syrup. Then close off the open end with the rubber band (as done previously). If any lite syrup does get onto the tubing, after folding over the other side of the dialysis tubing and tying it off with a rubber band, gently rinse the outside of the tubing with distilled water.
10. Gently pat the tubing dry with a paper towel. Place the plastic cup on the digital scale and tare the scale. Then, place the dialysis tubing with the lite syrup inside the plastic cup to determine the mass of the dialysis tubing/lite syrup. Record the mass.
11. Place the tubing filled with lite syrup into the distilled water in the cup or bowl. Ensure that the tubing is completely submerged. Allow the tubing to remain in the water for 30 minutes.
12. After 30 minutes, remove the tubing from the water. Gently pat the tubing dry with a paper towel and determine the mass of the dialysis tubing/corn syrup as done previously in Step 10. Record the mass.
13. Place the tubing filled with lite syrup back into the distilled water in the cup or bowl. Ensure that the tubing is completely submerged. Allow the tubing to remain in the water for another 30 minutes.
14. After 30 minutes, remove the tubing from the water. Gently pat the tubing dry with a paper towel and determine the mass of the dialysis tubing/lite syrup as done previously in Step 10. Record the mass.
15. Cleanup

Next

1. Gather the following equipment and set it up near a source of tap water: the large plastic cup, crushed ice (made from tap water), measuring spoon for a 0.5 teaspoon (~2.5 mL), salt, digital scale, thermometer, stopwatch, and 25 mL graduated cylinder.
2. Place 100 g of ice in the plastic cup. Place a cup on the digital scale and tare the cup. Carefully place enough ice in the cup, by adding small pieces, until you get 100.0 g.
3. Ensure that the thermometer and stopwatch are nearby. Pour 100 mL of tap water into the cup, using the graduated cylinder to pour the water in 25 mL at a time.
4. Begin timing for this exercise. Every 30 seconds, record the temperature of the water near the ice. Stir the solution continuously so the temperature is even throughout the cup. When measuring the temperature, keep the thermometer near the ice in the cup, remembering that ice floats in water. Record the temperature at each time point (every 30 seconds).
5. After recording is completed, empty the water and ice into a sink. Fully dry the plastic cup and repeat Step 2, weighing 100 g of ice in the cup.
6. Pour 0.5 tsp (2.5 mL) of salt into the plastic cup over the ice and stir. Ensure that when you stir the mixture, you also stir near the bottom of the cup to dissolve all of the salt into the solution.
7. Repeat Steps 4-6. When the water is poured into the cup, stir the water and salt mixture. Record all data.
8. Rinse the cup well with tap water a few times, pouring out the rinse water each time. Fully dry the plastic cup and repeat step 2, weighing 100 g of ice in the cup.
9. Pour 1.0 tsp (5 mL) of salt into the plastic cup over the ice and stir. Ensure that when you stir the mixture, you also stir near the bottom of the cup to dissolve all of the salt into the solution.
10. Repeat Steps 4-6. When the water is poured into the cup, stir the water and salt mixture. Record all data.
11. Make a graph of your data for all three columns of Data. Plot temperature on the y-axis and time on the x-axis. Input your data from the tap water and saltwater solutions. The 5 consecutive readings indicate the freezing point for the solution.
12. Cleanup

Next

1. Gather the following materials and set up near a source of tap water: 250 mL beaker, burner stand, burner fuel, matches, aluminum cup, aluminum pie pan, salt, measuring spoon for a 0.5 teaspoon (2.5 mL), thermometer, stopwatch, and 25 mL graduated cylinder.
2. Using the 25 mL graduated cylinder, measure 100 mL of tap water (in 25 mL increments), and pour the water into the 250 mL beaker.
3. Assemble the burner setup and light the fuel.
4. Boil the water in the beaker using the burner.
5. When the water is at a rolling boil, stir the water with the thermometer and take the temperature near the middle of the 250 mL beaker.  Record temperature.
6. Use the small, 2 oz. aluminum cup to extinguish the burner fuel flame. Carefully slide the burner fuel canister out from underneath the burner stand. The sides of the burner fuel canister will be warm, but not hot. Place the aluminum cup directly over the flame to smother it. The cup should rest on top of the fuel canister, with little or no smoke escaping. Do not disturb the burner stand and beaker; allow everything to cool completely.
7. Once the beaker has cooled, pour the water from the beaker down the drain.
8. Fully dry the beaker and repeat Step 2
9. Pour 0.5 tsp (2.5 mL) of salt into the beaker with water in it, and stir the mixture well with the measuring spoon or thermometer until the salt has dissolved into the mixture. Repeat Steps 3-7. Record data.
10. Rinse the beaker well with tap water a few times, pouring out the rinse water each time. Fully dry the beaker and repeat Step 2. Do not light the burner yet.
11. Pour 1.0 tsp (5 mL) of salt into the beaker with water in it, and stir the mixture well with the measuring spoon or thermometer until the salt has dissolved into the mixture.
12. Repeat steps 3-7. Record data.
13. Cleanup

Experiment 1.

From exercise one, the mass of the dialysis tubing increase over the given time period. The first 30 min the mass increased form 11.5g to 15.1g. For the second 30 min, the mass increased to 19.2g.

Time	Mass of dialysis tubing and contents
0	11.5g
30	15.1g
60	19.2g

Experiment 2

Time(sec)	Temp tap water	Temp solution 2.5 ml salt	Temp solution 5ml salt
30	4	1	0
60	3	1	0
90	1	1	-2
120	1	1	-2
150	1	1	-2
180	1	1	-2
210	1	1	-2
240	0	1	-2
270	0	1	-2
300	0	1	-2
330	0	1	-2
360	0	1	-2
390	0	1	-2
420	0	1	-2
450	0	1	-2
480	0	1	-2
510	0	1	-2
540	0	1	-2
570	0	1	-2
600	0	1	-2

Experiment 3

	Temp tap water	Temp solution 2.5 ml salt	Temp 5ml salt
Temp at rolling boil	101	103	105

Conclusion

These experiments showed us how a simple controlled substance can be altered by simply adding a solution to it. The freezing points and boiling points can be altered with the simple addition of salt and the mass of lite syrup can be greater if surrounding itself by water.The measurements of the water and salt could have been off if we did not use the graduated cylinder correctly or the right amount of salt. The dialysis could have had a pin hole in it allowing the water to come in more freely.Ultimately the data recorded in these experiments supported what science says should have happened in each test.

Questions

1.  In your experiment, is the light corn syrup in the dialysis tubing hypertonic or hypotonic to the water?

ANSWER: Hypotonic. The lite syrup gained mass over the given time period.

• 0.302 grams of an antibiotic was dissolved in 500 mL of water at 23.6°C. The solution has an osmotic pressure of 8.34 mm Hg. What is the molar mass of the antibiotic? Show your work.

ANSWER:

Solution

23.6*C = 296.75* K

8.34 mm Hg x 1/760 mm Hg = 0.0197 atm

0.0197 atm = M x (0.0821(L)(atm)/(mol)(K)) x 296.75 K

0.0197 atm = M x 24.36 (L)(atm)/(mol)

M = 0.0197 atm/24.36 x (mol^-1) x atm

M = 8.09 x 10^-4 mol/L

Mass per L = .302/.5L = 0.604g/L

0.604g/8.09 x 10^-4 mol = (x) grams/1.00 mol = 7.47 x 10^2 g/mol

Final Answer: 7.47 x 10^2 g/mol

• Describe the three freezing points. Is there a relationship between the amount of solute in the solution and the freezing temperature?

ANSWER:

The three freezing points are all slightly different. The solution with just water had a freezing point of 0* C. The solution with 0.5 tsp of salt lowered the freezing point to -1*C and the solution with the 1.0 tsp of salt dropped it to -2* C. The all dropped at the relatively same steady rate and began to flatten out at just about the same times.

• What are some practical applications of freezing point depression?

ANSWER:

Some practical applications of freezing point depression are antifreeze in a radiator.The antifreeze helps prevent the water from freezing in the radiator and during the months when we salt the roads to help melt the snow.

• Compare the three boiling points. Is there a relationship between the amount of solute in the solution and the boiling temperature?

ANSWER:

Yes, there is a relationship between the amount of solute in the solution and the boiling point temperature. As we can see from the data recorded in table 3, the boiling point temperature was increased with the amount of salt added to the solution.

• What are some practical applications of boiling point elevation?

ANSWER:

Antifreeze or coolant is another example again for boiling point elevation. The addition of coolant helps raise the boiling point temperature of the water solution to prevent the radiator from over-heating