Purity and Formulations

- A chemically pure substance will melt and boil at specific temperatures

- You can test the purity of a substance by measuring its melting and boiling points and comparing them with that of a pure substance

- The closer the measured value is to the actual melting or boiling point, the purer the substance

- Impurities in the sample will lower the melting point and increase the melting range of the substance

- Impurities will also increase the boiling point and may result in the same boiling over a range of temperatures

- Typically, referring to something as pure means that nothing has been added to it so it is in its natural state (pure milk, beeswax)

- In chemistry, a pure substance is one that only contains one compound or element throughout, and is not mixed with anything else

- Useful mixtures with a precise purpose that are made by following a formula - each component in a formulation is present in a measured quantity and contributes to the properties of the formulation so that it meets the required function

- They are really important in the pharmaceutical industry - altering the formulation of a pill can allow chemists to make sure that it delivers the drug to the correct part of the body at the right concentration, that it is consumable and has a long enough shelf life

- Formulations can be found in cleaning products, fuels, cosmetics, fertilisers, metal alloys and even food and drink

- When buying a product, there may be information about its composition on the packaging - ratio and percentage of each component - this tells you that a product is a formulation and also lets you choose the formulation with the right composition for your particular use

- Pigment - gives the paint colour - titanium oxide is used as a pigment in white paint

- Solvent - used to dissolve the other components and alter the viscosity (runniness)

- Binder (resin) - forms a film that holds the pigment in place after it has been applied to a surface

- Additives - added to further change the physical and chemical properties of the paint

- Depending on the purpose of the paint, the chemicals used and their amounts will be changed so that the paint produced is for the right job