Acids + Alkalis

• • Acids are a group of chemicals.
  • Everyday acids often taste sharp or will sting if you get them in a cut.
  • Laboratory acids have the hazard symbol ‘irritant’ or ‘corrosive’ on them.
• The pH scale is used to measure how acidic or alkaline something is. It goes from 0 (very acidic) up to 14 (very alkaline).
• A neutral substance has a pH of exactly 7, which means it doesn't react with anything else.
• Alkali is another name for base. A base has a pH above 7, so it reacts with acids to make salt and water.
• • Indicators are a special type of chemical that will turn a different colour in acid or alkali conditions.
  • Universal indicator can either be as paper or a solution.
  • If you put universal indicator into an unknown solution, it can turn any colour of the rainbow to show you whether you have an acid or an alkali.
  • Universal indicator will also show you how strong your acid or alkali is based on the colour.
• • Alkalis are also a group of chemicals.
  • Many soaps are alkalis and laboratory alkalis are also ‘irritant’ and ‘corrosive’.
  • Alkalis can be thought of as the opposite of acids.
• • Litmus paper is either blue or red in colour and will change colour to tell you whether you have an acid or alkali.
  • If you have an acid, the paper will be red.
  • If you have an alkali, the paper will be blue.
  • Litmus paper cannot tell you how strong the acid or alkali is.
  • Red litmus paper will not change colour in acid or neutral.
  • Blue litmus paper will not change colour in alkali or neutral.