(SC1) States of Matter and (SC2) Separation techniques Flashcards
Solute is…
dissolved substance
Solvent is…
liquid in which solutes are dissolved
Crystallisation is…
when the solvent is evaporated to leave the solutes behind.
Describe crystallisation process…
evaporating basin with the solution is put on top of the beaker with water. Beaker is heated up and the vapours from boiling water heat the basin. Solvent is evaporated and the solution gets more concentrated. Eventually, all of the solvent is evaporated and only solute is left behind = saturated solution.
Describe filtration
A filter funnel is lined with filter paper that has fine holes in it. The solvent and solute pass through the fine holes to form the filtrate. Bits of insoluble substances cannot fit through the holes and so leave a residue in the filter paper.
What is chromotography used for? (4)
It is used to:
- find out which coloured compounds the mixture contains.
- distinguish between pure and impure substances.
- identify subtances by comparing the pattern on the chromotogram with the patterns formed by known substances
- identify substances by calculating their Rf values
Why does chromotography work?
It works because some compounds dissolve better in a solvent than others.
Describe chromotography
Draw a baseline at the bottom of chromotography paper then add samples on that baseline. Chromotography paper is then placed into the solvent (water or ethanol) in the beaker. Do not submerge a baseline and the sample. Place lid on top of the beaker to stop evaporation. Wait until the solvent will seek up and reach the top of the paper. Dyes will dissolve in the solvent and move up. Each dye travel to a different rate, which tells us that each different rate must be a different substance.
Stationary phase is…
a substance or materials that the molecules can’t move in (eg solid)
Mobile phase is…
a substance or materials that the molecules can move in (eg liquid, gas)
Rf value is…
the distance the compound has risen divided by the distance the solvent has risen. The Rf value of a particular compound does not change of the chromotography conditions used remain the same.
What is the apparatus that is used for distillation?
Still
What is distillation can be used to? (3)
It can be used to:
- seperate the different products in crude oil
- make alcoholic drinks, such as vodka or whisky
- seperate out the gases in the air, after the air has been cooled and turned into a liquid at -200 degrees
Describe distillation
A column is fixed above the distillation flask. The hot vapour rises up the column. At first, the vapour condenses when it hits the cool glass and drips back into the flask. As the column gradually heats up, there will be a temperature gradient - it will be hottest at the bottom and the temperature will drop as you go further up the column.
How to make a drinkable water not using any chemical reactions?
First of all, the water is poured into a sedimentation tank where small particles are allowed to settle out. Secondly, water is filtrated through sand and grave in a filtration tank. Thirdly, chlorine is added to kill microorganisms in the treated water.
