C1 - Filtration, Crystallisation

What do physical separation techniques separate?

Mixtures (not compounds).

Can physical separation techniques be used to separate elements in a compound?

No, compounds must be separated by chemical reactions.

What are two examples of chemical reactions used to separate elements in compounds?

Reduction and electrolysis.

What is filtration used for?

To separate an insoluble solid from a liquid.

What does "insoluble" mean?

The substance does not dissolve in a liquid.

Give an example of a mixture that can be separated by filtration.

Silver chloride and water.

What are state symbols?

Letters that describe the physical state of a substance (solid, liquid, gas, aqueous).

What does the state symbol (s) mean?

Solid.

What does the state symbol (l) mean?

Liquid.

What does the state symbol (g) mean?

Gas.

What does the state symbol (aq) mean?

Dissolved in water (aqueous solution).

What is the state symbol for silver chloride in water if it does not dissolve?

(s) — solid.

What equipment is used in filtration?

Filter funnel and filter paper.

What happens to the liquid during filtration?

It passes through the filter paper and is collected as the filtrate.

What happens to the solid during filtration?

It is trapped in the filter paper.

What is the liquid called after filtration?

The filtrate.

What is the residue in filtration?

The solid left behind on the filter paper.

What type of separation is filtration?

Physical separation.

What is crystallization used for?

To separate a soluble solid from a liquid.

What does "soluble" mean?

The substance dissolves in a liquid.

Give an example of a mixture that can be separated by crystallization.

Sodium chloride and water.

What happens when sodium chloride dissolves in water?

It forms a sodium chloride solution.

What does the state symbol (aq) mean for sodium chloride?

It is dissolved in water (aqueous).

What happens during crystallization?

The water evaporates, leaving behind crystals of the solid.

How can we speed up crystallization?

By gently heating the solution.

What is a risk of heating during crystallization?

Some substances can break down (decompose) when heated.

What happens if you leave a sodium chloride solution uncovered for a few days?

The water evaporates and crystals of sodium chloride form.

What is the change in state symbol for sodium chloride after crystallization?

It changes from (aq) to (s).

Why is crystallization a physical separation method?

Because it does not involve a chemical reaction.

Why is it better to let water evaporate slowly during crystallization?

To avoid decomposition of heat-sensitive substances.

Can filtration be used to separate dissolved substances?

No, it only works for insoluble solids.

Can crystallization be used for insoluble solids?

No, it is used only for soluble solids in solution.

Why are separation techniques important in chemistry?

They allow us to isolate and purify substances from mixtures.

Which separation technique would you use for sand and water?

Filtration.

Which separation technique would you use for salt and water?

Crystallization.

What does the term 'mixture' mean in chemistry?

A combination of substances not chemically bonded.

What is an aqueous solution?

A solution where a substance is dissolved in water (state symbol aq).

Why can't you separate compounds with filtration or crystallization?

Because the elements in compounds are chemically bonded.