Separation techniques.

Mixtures.

A mixture is 2 or more elements that are not chemically bonded.

As they are not chemically bonded, they are easy to separate.

You can change the amounts of the different substances in a mixture, and the substances in a mixture keep their properties.

If they have become chemically bonded(compound), a new substance has been made, and it is no longer a mixture.

How to identify pure and impure substances.

A pure substance is a substance that has no other substances mixed with it.

An impure substance is a substance that has different substances mixed within it.

Pure substances have sharp melting points.

Examples of separation techniques.

The magnet will attract magnetic materials, such as iron, and leave non-magnetic materials behind.

Funnel and filter paper have tiny holes in them. Only extremely small particles can get through. Large particles will stay on the filter paper.

Sieve-sieves contain holes. Only particles that are smaller than the holes can get through. Larger particles will stay inside the sieve.

Solutions.

A solution is when a solid or gas dissolves into a liquid.

This forms a mixture.

When a solute dissolves into a solvent, the solute particles break apart and mix with the solvent's particles.

The individual components that make up a mixture are called components.

Equation of a solution.

Solute+solvent=solution.

(Solid/gas)+(liquid)=(dissolved mixture).

Testing solutions.

1. Taste/smell(sensory).

2. Boiling points(pure substances have consistent boiling points. But solutions do not).

3. Mass(solutions have greater mass due to the solute + solvent mass together).

Solubility.

Solubility- How easy it is for a solute dissolves into a solvent.

The solubility of a substance varies with the temperature.

Soluble- Can dissolve.

Insoluble- Can not dissolve.

Saturated solution- A solution with the maximum mass of solute dissolved.

Filtration

Filtration -The process of separating a liquid from an insoluble solid.

For example, Filter paper contains tiny holes that only water molecules are small enough to fit through.

Any other molecules trapped in the paper are called residue.

In the liquid state, water passes through the holes. This is called the filtrate.

When a solution has been formed, the solute has dissolved and, therefore, can not be filtered from the solvent.

When you filter a mixture of a saturated solution and its undissolved solid, only the undissolved solid will end up in the paper.

Evaporation and distillation.

Evaporation -The process of a liquid turning into a gas.

Condensation - The process of a gas turning into a liquid.

Factors affecting condensation.

1. Humidity

2. Temperature.

3. Wind.

4. Surface area.

Distillation- The separation of substances using evaporation and condensation based on different boiling points.

1. Water in the salt solution boils.

2. Steam leaves the solution.

3. Steam travels through the condenser and cools down.

4. The steam condenses to form liquid water.

5. Distilled liquid water drips into the beaker.

Chromatography.

Chromatography is a technique that is used to separate two or more substances that have been dissolved in a solvent/separate substances in a mixture.

You can separate substances is a mixture by chromatography if all the substances are soluble in the same solvent.

Separating substances are based on their solubility.

The more soluble, the further up the paper will go.

Key practical points

1. The baseline must be in pencil so that it won’t contaminate the ink spot.

2. The baseline must be above the solvent so that the ink moves up the paper properly.

3. The bottom of the paper must be touching the solvent so water can move up.