2.2.3

Acids & Alkalis

Test yourself

Acids and Alkalis

Many chemicals can be classed as either acids or alkalis.

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Acids

  • 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.
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Alkalis

  • 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.
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Universal indicators

  • 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.
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Litmus paper

  • 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.

Jump to other topics

1Biology

1.1Cells, Tissues & Organs

1.2Reproduction & Variation

1.3Ecological Relationships & Classification

1.4Digestion & Nutrition

1.5Plants & Photosynthesis

1.6Biological Systems & Processes

2Chemistry

2.1Particles

2.2Chemical Reactions

2.3Atoms, Elements, Compounds

2.4The Periodic Table

2.5Materials & the Earth

2.6Reactivity

2.7Energetics

2.8Properties of Materials

3Physics

3.1Energy

3.2Forces & Motion

3.3Waves

3.4Electricity & Magnetism

3.5Matter

3.6Space Physics

4Thinking Scientifically

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