Question

What would be the purpose of this lab based on the following information?

Colligative Properties II

Colligative Property is a property of a solution that depends only on the number of solute molecule present. Osmotic pressure, freezing point depression, boiling point elevation, and vapor pressure lowering are all colligative properties. In today’s lab we will look at three of these properties.

Electrolytes are substances that forms ions in solution that conduct electricity. Electrolytes can either be an acid, base or a salt. Not all electrolytes conduct electricity to the same degree. Strong electrolytes 100% ionizes in water and therefore the solution contains more ions. This means that the solution will be a strong conductor of electricity. Weak electrolytes only partially ionizes in water and therefore the solution contains less ions. This means that the solution will be a weak conductor of electricity. Nonelectrolytes are substances that do not dissociate when dissolved in water. Since there are no free ions present, the solution does not conduct electricity. Nonelectrolytes include all covalently bonded compounds. In today’s lab, you will use a conductivity probe to determine if a solution is a strong electrolyte, weak electrolyte or nonelectrolyte.

The freezing point of a solvent can be lowered and the boiling point raised by adding a solute to the solvent. How far the freezing point is lowered is dependent upon the number of solute molecules present in the solution. Some substances, called electrolytes, dissociate in water and breaks down into its individual ions while other do not. Since the freezing point depression, boiling point elevation, and osmotic pressure depends on the number of particles in the solution, the more particles in solution the greater the change in boiling point, freezing point depression and osmotic pressure.

When two solutions of different concentrations are separated by a semipermeable membrane, the solvent will flow through the semipermeable membrane from a solution of lesser concentration to that of greater concentration. This process is called osmosis. When the pressure becomes sufficient, the rate of solvent transfer is equal for both sides therefore the volume changes cease and the system is in equilibrium. The net result is the dilute solution is now more concentrated in solute and the concentrated solution is less concentrated in solute. In the first part of this lab, we will determine how the concentration of a solution that was left from last week is affected by osmosis.

Answer 1

There is a lot of discussion regarding colligative properties: freezing point depression, boiling point elevation and osmotic pressures, which are properties of solutions that depend only on the concentration and not on the identity of the solute.

The purpose seems to be (at least for the first part, as it says), to study the osmosis process using a solution that was previously prepared. My guess is that you will have to determine how concentration affects the difussion of your solute through an osmosis membrane.

There isn't any more information on other experiments, but you will surely perform freezing point depression and boiling point elevation and, again, will study how these fenomena can be explained in terms of solute concentration.

If there's something more you need, I'll try to help you in the comments, let me know!