Purity, Formulations and Chromatography

• A pure substance is a single element or compound, not mixed with any other substance
• Pure substances melt and boil at specific temperatures. This melting and boiling points data can be used to distinguish pure substances from mixtures
• In Chemistry a Pure substance is a substance that has had nothing added to it, so it is in its natural state, e.g. pure milk, distilled water
• A formulation is a mixture of two or more substances that are intended to be used together for a specific purpose
• They are made by mixing the components in carefully measured quantities to ensure that the product has the required properties Examples are fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods
• Chromatography is used to separate mixtures and give information to help identify substances
• To calculate the Rf value, it is the distance travelled by the substance ÷ the distance moved by the solvent
• The more soluble a substance is, the further up the paper it travels