An acid is a substance that turns blue litmus paper red and has a pH less than 7. Acids have a sour taste.
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A base is a substance that turns red litmus paper blue and has a pH greater than 7. Bases have a soapy feel.
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An alkali is a basic substance which is soluble in water.
Neutral substances are neither acidic nor basic. Their pH is exactly 7.
The pH scale shows how acidic or alkaline a substance is and runs from 0 to 14.
An indicator is a substance that shows whether a solution being tested is an acid or a base.
Indicators contain a dye that turns a different colour in acidic or alkaline solutions. Commonly used indicators are litmus indicator and universal indicator.
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A neutralisation reaction is a reaction between an acid and a base to form a neutral substance.
An acid and a base react to produce a salt and water.
An acid and a carbonate react to produce a salt, water and carbon dioxide.
An acid and a metal react to produce a salt and hydrogen gas.
A salt is a chemical compound, formed when the hydrogen part of an acid is replaced by a metal.
Hydrogen gas is explosive and burns with a pop.
TheBIGChallenge
Your challenge is to keep a chemical food diary. Over the course of one day, record the different types of chemicals you eat. You will find these in the ingredients list on food labels or online.
Once you have completed your diary, identify the acids and bases present in your diet. The acids should be easy to identify as they will have ‘acid’ in their names, but you may need to carry out research on some of the less obvious ingredients.
Complete a table with the following headings: zz
Chemical
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Food present in Acid or base?
Identify the most common acid and base you consume and research other uses of these substances.
