Colligative properties freezing point depression and molar mass lab report

Final Report

Exercise 1

Data Table 1: Dialysis Tubing Results

CHEM 182 DL1 Colligative Propert ies and Osmotic Pressure

The light corn syrup in the dialysis tubing is hypotonic to the water because it increased in mass over the amount of time.

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

The molar mass of the antibiotic is 7.47 x 102 g/mol. This is because: 23.6 C = 296.75 K. 8.34 mm Hg x 1/760 mm Hg = .0197 atm. .0197 atm = M x (.0821 (L)(atm) / (mol)(K)) x 296.75 K. .0197 atm / 24.36 (L)(atm) / (mol). M = .0197 atm / 24.36 x (mol-1)(atm). M + 8.09 x 10-4mol/L. .604 g / 8.09 x 10-4mol = g / 1 mol = 7.46 x 102g/mol.

2. 0.302 grams of an antibiotic was dissolved in enough water at 23.6°C to make 500.0 mL of solution. T he solution has an osmotic pressure of 8.34 mm Hg. What is the molar mass of the antibiotic? Show your work.

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Exercise 2

Data Table 2: Temperature Readings for Freezing Point

Time Mass of Dialysis Tubing and Contents

0 minutes

30 minutes

60 minutes

17.2g

20.9g

25.2g

The three freezing points all differ. The first was 2, the second 0, and the third -2. I think there is relationship between the amount of solute in the solution and the freezing temperatures because each started at a lower temperature than the one before and they dropped and ended at a lower freezing point than the one before.

1. Describe the three f reezing points. Is there a relationship between the amount of solute in the solution and the f reezing temperature?

Some practical applications of freezing point depression are antifreeze for example, used in car radiators. Also, salt, when it is used on ice in winter.

2. What are some practical applications of f reezing point depression?

Time (seconds) Temp (°C) of Control (tap water)

30

60

90

4

3

3

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120

150

180

210

240

270

300

330

360

390

420

450

480

510

540

570

600

Time (seconds) Temp (°C) of Solution +0.5 tsp (~2.5 mL) salt

30

60

3

2

2

1

1

1

1

1

1

1

1

1

1

1

0

0

0

2

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90

120

150

180

210

240

270

300

330

360

390

420

450

480

510

540

570

600

Time (seconds) Temp (°C) of Solution +1.0

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

0

0

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tsp (~5 mL) salt

30

60

90

120

150

180

210

240

270

300

330

360

390

420

450

480

510

540

570

0

0

-1

-1

-1

-2

-2

-2

-2

-2

-2

-2

-2

-2

-2

-2

-2

-2

-2

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Graph 1: Freezing Point Depression of Salt Solutions

Exercise 3

600 -2

The three boiling points were quite close. I think there is a relationship between the amount of solute in the solution and the boiling temperature because the more solute, the higher the boiling points were.

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

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Data Table 3: Temperature Readings for Boiling Point

Some practical applications of the boiling point elevation are when ethylene glycol is added to increase the boiling point of a solution or when we use salt in the water when we cook in order to make the food boil quicker.

2. What are some practical applications of boiling point elevation?

Temp (°C) of Control (tap water)

Temperature at Rolling Boil

Temp (°C) of Solution +0.5 tsp (~2.5 mL) salt

Temperature at Rolling Boil

Temp (°C) of Solution +1.0 tsp (~5 mL) salt

Temperature at Rolling Boil

101 ºC

104 ºC

106 ºC