Purity, formulations and chromatography (paper 2)

How is purity worked out?

By looking at the melting or boiling points of samples, closer value = the purer the substance

Examples of pure substances?

1. Water
2. Oxygen
3. Copper sulfate
4. Sodium chloride

How do impurities affect the melting point of a sample?

They decrease it

How do impurities affect the boiling points of samples?

They increase it

What is chromatography?

It’s a process that separates a mixture into its different components

What is the mobile phase?

Liquid or gas

What is the stationary phase?

Solid or viscous liquid

How do we know if a substance is more attracted to the mobile phase (liquid or gas)?

Substance will move far

How do we know if a substance is more attracted to the stationary phase (solid or viscous liquid)?

Substance doesn’t move far

Why can the number of spots of a mixture vary?

Depends on the solvent being used

What’s a reference substance?

A pure substance that’s run next to the tested substance to see if its a component in the mixture

How many chromatography spots are produced by pure samples, and why?

* pure substances consist of a single element or compound
* They will only produce 1 spot