EXPERIMENT 4 Determination of Molal Freezing Point Depression

Theory: A pure liquid has its own physical properties such as boiling point and

Theory: Colligative properties of solution: 1. Lowering in vapor pressure. 2. Boiling point elevation.

Procedure: 1. Weight dry test tube (W 1). 2. Add about 15 ml of

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EXPERIMENT (4) Determination of Molal Freezing Point Depression Constant

Theory: A pure liquid has its own physical properties such as boiling point and freezing point, but when a solute (non ionized & non volatile) is dissolved in this liquid to prepare a solution these properties will change (colligative properties).

Theory: Colligative properties of solution: 1. Lowering in vapor pressure. 2. Boiling point elevation. 3. Freezing point depression. 4. Osmotic pressure. Colligative properties depend on the number, but not the kind of solute particles in a given amount of solvent.

Procedure: 1. Weight dry test tube (W 1). 2. Add about 15 ml of benzene in the test tube, then re-weight the test tube (W 2) and find the weight of benzene (W 3). 3. Put the test tube in water bath, then in ice bath to lower the temperature very slowly. 4. Record the temperature at which it become constant at freeze (T 1). 5. Transfer exactly 2 gm of naphthalene to the test tube containing benzene. 6. Return the test tube to the water bath, the to the ice bath. 7. Record the constant temperature (T 2).