1.8 explain how information from chromatograms can be used to identify the composition of a mixture.

CHROMATOGRAMS:

- Are a visible way of showing the separations of components. The shape shown can be compared with already discovered shapes to be able to match the component.

RF VALUES:

- Is calculated by DISTANCE TRAVELLED BY COMPONENT
                             DISTANCE TRAVELLED BY SOLVENT

(Distance travelled by component / Distance travelled by solvent)

1.7 describe experimental techniques for the separation of mixtures, including simple distillation, fractional distillation, filtration, crystallisation and paper chromatography

SIMPLE DISTILLATION:

- It can be used to separate liquids that contain liquids. The solution is heated until the part of the solution, with the lowest boiling point, evaporates. The vapour of that part is then cooled which turns the vapour back to a liquid. It isn't all so good though, you can only separate things with very different boiling points; for similar boiling points you need fractional distillation.


FRACTIONAL DISTALLATION:

- Is used to separate a mixture of liquids. A typical example is separating crude oil to get different fractions. It can be done in a few simple steps; if you place a fractionating column on top of a flask and heat it the different parts have different boiling points; they will eventually evaporate at different temperatures. As the substance gets hotter, the different fractions form. The lower ones first then the higher ones later, however the column is cool at the top therefore condenses into a liquid which can be collected.

FILTRATION:

- It can be used to separate an insoluble solid from a liquid. The liquid is placed onto filter paper in a funnel for the liquid to be filtered through past the solid.

CRYSALLISATION:

- This is used to separate a soluble solid from a solution; the solution is poured into an evaporation dish. The solution is then heated, to make the solution more concentrated, until crystals start to form. The solution is then removed and left in a warm area to let crystals form.

CHROMATOGRAPHY:

- It is a method used to separate components from each other. The different dyes move up the paper at different speeds, this is because of the size of the particles. Some are big and therefore stick to the paper but some are small and dissolve very quickly, allowing that component to travel quicker in the solvent.

1.6 understand the differences between elements, compounds and mixtures

ELEMENTS:

- They only consist of one type of atom.

COMPOUNDS:

- They are substances that are only made up of two or more different elements. They have to be bonded. Since they are bonded it is a lengthy process to separate the original elements.

MIXTURES:

- They are substances that contain multiple different elements, but they are not bonded. This makes it easier to separate the different elements.

1.5 understand the terms atom and molecule

ATOMS:

- An atom consists of a nucleus which contains protons and neutrons. Around the nucleus are shell(s) which have a certain amount of electrons on them de
pending on how many electrons the substance has.

MOLECULES:

- When atoms join they form molecules. (Remember it can be made from just one element as well as multiple elements). Molecules are only held together by covalent bonds.

1.4 describe and explain experiments to investigate the small size of particles and their movement including: i dilution of coloured solutions ii diffusion experiments

Diffusion is where particles move from a high concentration to a low concentration. Think of it as stuff spreading out (like perfume being sprayed into the air)

1st EXPERIMENT:

- Potassium Manganate(VII) and water, if you have a beaker of water, slowly place some potassium manganate(VII) to the bottom. The purple "stuff" will diffuse out into the water spreading a purple colour.
- Basically the potassium manganate(VII) particles are diffusing into and around the water. From 1.1, we know that liquid moves in a random motion which therefore causes the potassium manganate(VII) to spread out evenly.

- The experiment can then be repeated to test dilution. If you add water to the potassium manganate(VII) solution, the particles would spread out further due to the random motion evenly spreading it out. This results in the solution being less purple.



2nd EXPERIMENT:

- Ammonia and Hydrogen Chloride, when the two are placed into a tube eventually a white ring of ammonium chloride forms. This is because the ammonia diffuses from one end and vice versa with the hydrogen chloride. From the picture we can see that the ring is not in the middle, this is due to the particles of ammonia being smaller and lighter hence being able to travel faster than hydrogen chloride.



3rd EXPERIMENT:

- Bromine Gas and Air, are a great to test for diffusion because of the strong brown colour (and smell). All you need is: two cups and a separator. If you fill one cup with bromine gas and the other with air and put them on top of each other, between a separator, then remove the separator you will see brown bromine gas diffuse into the air. As of the liquid, the random motion causes it all to spread out evenly.