Solubility
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Solvent
The liquid
Solute
The solid
Soluble
Dissolvable
Insoluble
Not dissolvable
Why is water the most common solvent used?
It’s easily available, cheap and dissolves many different solids.
A saturated solution
A solution that cannot dissolve any more solute because too much of it has been added. This can be fixed by adding more solvent or increasing temperature.
Salt is a solid which —— in water
Dissolves
Salt water is a ——
Solution
Other dissolvable substances
Sugar, instant coffee
What is a solution?
The mixture produced when a solute dissolves in a solvent.
What is a mixture?
Substances that are not chemically combined.
Define dissolve
When the solvent “breaks” apart the solute particles to form a solution
Define supspension
When the solid is evenly spread throughout the liquid… will eventually sink but is makes the solution go cloudy
Define sediment
Solid particles sit at the bottom of the liquid… not mixing
Explain the process of filtration
Separating a solid from a liquid by filtering the solution so the solid stays and liquid goes.
Solubility Rules
All compounds that contain sodium, potassium and ammonium are soluble All nitrates are soluble Most sulphates are soluble (exceptions: silver sulphate, barium sulphate, calcium sulphate & lead sulphate) Most chlorides are soluble (exceptions: silver chloride and lead chloride) Most carbonates, oxides and hydroxides are insoluble (exceptions: sodium, potassium and ammonium compounds)
Why does coffee dissolve better in hot than cold?
Because the particles move more vigorously when heated
Explain evaporation
The salty water is put in an evaporation basin. Left in warm place where water evaporates and leaves salt crystals.
Explain purifying rock salt
Dissolve rock salt in water Filter to remove rock Evaporate water to get pure, dry salt
Where can you lose salt in the process or purifying rock salt
Some of the salt is sand Some spits out Some stays in the beaker
Explain distillation
Distillation is used to separate. It’s the process of heating a liquid solution to form vapour and then condensing it to get a liquid. For example, if we have copper sulphate but we only want water or just the copper sulphate then we can separate it. First we heat it because the water will evaporate first. Then as the water has evaporated we condense it so it is a liquid but separate.
Why will simple distillation not work if the difference between the 2 boiling points is less than 25 degrees?
Because the components don’t get separated and purified completely
What is fractional distillation?
It is used for separating a mixture of liquids
What is chromatography?
Can be used to separate mixtures of coloured compounds eg. Inks, colouring agents