Flashcards in Seperating Mixtures Deck (16):
Describe how to carry out distillation
1. Heat a conical flask with a solution in it.
2. The solvent will evaporate and condense in the tube coming out the top.
3. It will drop into a test tube.
A) What is a miscible liquid
B) How can we separate it
A) A liquid that is mixed.
B) Fractional distillation (boiling at the temperature of the lower boiling point)
Describe how to purify a solid by recrystallisation
1. Dissolve it in water
2. Filter it
3. Allow the water to evaporate
How do you do paper chromatography
1. Draw a base line and put different coloured dyes at the bottom
2. Loosely roll the paper and put it into a beaker solvent which is shallower then the baseline.
3. When the solvent front is near the top, take the paper out and mark where the solvent got to
How does chromatography work
It works because the dyes have different colours and some dissolve more readily and travel with the solvent quicker, while others stick to the paper.
A) How can you work out the Rf value
B) Why is this useful
A) Distance moved by chemical/distance moved by solvent front
B) If you use the same paper and the same dye the Rf values will always be the same.
Describe a solid: Describe the forces of attraction between the particles, how much the particles move and what happens when they are heated.
Strong force of attraction, the particles only vibrate and stay in a lattice arrangement, when heated the particles vibrate more.
Describe a liquid: Describe the forces of attraction between the particles, how much the particles move and what happens when they are heated.
Weak force of attraction, don’t have a definite shape or volume or shape and fills the bottom of a container, when heated the constantly moving particles move faster.
Describe a gas: Describe the forces of attraction between the particles, how much the particles move and what happens when they are heated.
Incredibly weak force of attraction, don’t have a definite shape or volume and fill a container, when heated it either expands or the pressure increases.
Describe what happens to the particles in a physical change
All they change is their arrangement and their energy, not what particles they are.
Draw a diagram of how the states change
At the substances melting point, the particles have enough energy and break free from their positions
When a liquid is heated, the particles gain energy and break the bonds and make a gas.
What is diffusion?
The gradual movement of particles from a dense place to a scarce place, this is natural and the particles spread out.
Describe how ammonia and hydrogen chloride can be used to demonstrate diffusion
Cotton wool is placed at one end of tube which gives of ammonia gas while more cotton wool at the other end gives off low hydrogen chloride gas. A white ring appears near the hydrochloride acid as when the two substances mix, they react. It is further away from the aqueous ammonia as ammonia is lighter and therefore diffuses quicker.