A chemically pure substance is a single element or compound. It contains only one substance. Purity is worked out by looking at the melting and boiling point of samples
Effects of impurities in a sample
Decreases melting point
Increases boiling point
Increases range of temperatures
Formulations
In a formulation, each component helps to decided the mixture's overall properties
To ensure that a formulation does what it is supposed to, each chemical component must be present in a precisely measure quantity
Chromatography
Used to separate mixtures and give information to help identify substances
Involves a stationary phase and a mobile phase
Mobile phase - substances picked up and carried (Liquid or gas)
Stationary phase - solid or viscous liquid
Separation depends on the distribution of substances between phases
RF value
Distance moved by substance/ distance moved by solvent
Always less than 1
How well the spot is retained to the paper
Paper chromatography
capillary tube is used to dab a spot of solution on pencil line near bottom of the sheet of chromatography paper. paper placed standing in solvent at the bottom of the beaker. The solvent soaks up the paper, running through the spot of mixture
The solubility of the components of the mixture depends on how far they travel up the paper
