Purity & Formulations

• Chemical analysis is about the instruments and methods used to separate, identify and quantify different substances.
• A pure substance is something that only contains one type of compound or element
• a mixture of two different compounds cannot be pure
• only pure substances melt and boil at specific temperatures, for example water boils at 100 degrees Celsius, and sodium chloride melts at 801 degrees Celsius. To test if water is pure, you can use a physical test (testing the physical properties of that substance) to see if it boils exactly at 100 degrees Celsius.
• Reacting a substance with another chemical to find out what it is a chemical test
• Impure substances don't have specific melting/boiling points. They melt and boil over a range of temperatures dependant on the quantities of each item in the mixture.
• Generally having an impure substance will lower the melting point but increase the boiling point. For example, pure water melts at 0 degrees Celsius and boils at 100. But salt water melts at around -2 degrees Celsius and boils at 100.5.
• Formulations are mixtures that have been prepared using a specific formula. This means they have precise amounts for a particular function. Formulations are used for fuels, cleaning agents, paint, medicines, alloys, fertilisers, and food + drink.
• In formulations, the different components are always present in the same proportion.