Separating Mixtures

 A mixture is made when two or more substances are combined, but they are not combined chemically.
General properties of a mixture:
The components of a mixture can be easily separated.
The components each keep their original properties.
The proportion of the components is variable.
A mixture is the combination of two or more substances that can be easily separated.
True or False?

• True
• False

 Filtration is a common method of separating an insoluble solid from a liquid. An example of a mixture is sand and water. This process involves the use of a filter paper placed in a filter funnel. The funnel is placed in a beaker and the mixture of water and sand is poured into the funnel. The liquid part drains through the filter paper into the beaker, leaving the solid sand particles trapped on the filter.
Filtration is a common method of separating an insoluble solid from a liquid.
True or False?

• True
• False

In filtration, the liquid part collected is called the filtrate and the solid bit that remained on the filter paper is called the residue.
In filtration, what is the part that remains called?

• Solid
• Filtrate
• Remainder
• Residue

In some cases there are suspension mixtures where the solid particles are too fine to be separated with a filter. In these cases, sometimes a centrifuge is used. Centrifuges are mechanical devices that spin at very high speeds. These high speeds allow the solid particles in suspensions to settle very quickly.
When is a centrifuge used?

• where the mixture is chemically combined
• for big particles
• for large amounts
• where the solid particles are too fine to be separated with a filter

Evaporation is good for separating a mixture (solution) of a soluble solid and a solvent. The process involves heating the solution until the solvent evaporates (turns into gas) leaving behind the solid residue.
Evaporation is good for separating a mixture (solution) of a soluble solid and a solvent.
True or False?

• True
• False

A mixture of salt and water. To get the salt back from the salt water, the solution is heated to boiling point. As it boils, the water escapes as vapor (gas). After a while, all the water evaporates, leaving a layer of salt at the bottom of the glass.
To remove the salt from salt water, the easiest thing to do is boil it and evaporate the water.
True or False?

• True
• False

 Simple distillation is best for separating a liquid from a solution. It is similar to evaporation, but the vapor is collected by condensation.
To separate pure water from a salt solution: A beaker of salt solution is heated to boiling point. As it boils, the liquid turns into vapor (gas). The vapor is directed through tubes (condenser) connected to another beaker. As the vapor goes through the tube, it is cooled down by running cold water round the tubes. This forces the temperature of the vapor to fall, causing the gas to turn into liquid again (condensation).

• the vapor is collected by freezing
• the vapor is collected by filtration
• the vapor is collected by condensation
• the vapor is collected by heat transfer

Fractional distillation is similar to simple distillation. It is best for separating a solution of two liquids. (liquids that dissolve in each other). Fractional method takes advantage of the different boiling points of the two liquids. Fractional distillation takes a bit more time than the simple distillation.
Fractional distillation takes less time than the simple distillation.
True or False?

• True
• False

Magnetism is ideal for separating mixtures of two solids with one part having magnetic properties. Some metals like iron, nickel and cobalt have magnetic properties whiles gold, silver and aluminum do not. Magnetic elements are attracted to a magnet.
How would you separate iron filings mixed with sand?

• evaporation
• fractional distillation
• filtration
• magnetism

 In the 'separating funnel technique', two liquids that do not dissolve very well in each other can be separated by taking advantage of their unequal density. A mixture of oil and water can be separated by this technique.
The two liquids in the mixture have different densities, making the heavier liquid settle at the base of the container. A funnel with a tap at the spout is placed inside a beaker. The mixture is poured into the funnel and allowed to settle. Soon, the oil, which is heavier, settles at the base, with the water on top of it. The tap is opened to allow the oil to pass, and closed as soon as the water reached the spout.
What does the 'separating funnel technique' take advantage of to separate two liquids?

• unequal particles
• unequal temperatures
• unequal densities