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C3 Acids, bases and alkalis
An acid is known as a proton donor- they release H+ ions.
A base is known as a proton acceptor- they accept OH- ions.
An alkali is a base that can be dissolved in water.
Acids and alkalis are either `strong' or `weak', this depends on how much they
ionise in water.
A `strong' acid or alkali is one which is completely ionized in water.
Examples of strong acids:
Hydrochloric acid (HCl)
Sulphuric acid (H2SO4)
Nitric acid (HNO3)
Examples of strong alkalis:
Sodium hydroxide (NaOH)
Potassium hydroxide (KOH)
A `weak' acid or alkali is one that is only partially ionized in water.
Examples of weak acids:
Carbonic acid (H2CO3)
Ethanoic acid (CH3COOH)
Examples of weak alkalis:
Ammonia solution (NH3)
Detecting whether an acid is `weak' or `strong':
1) Observe the amount of time it takes for the acid to react with a metal, if it
reacts quickly it is a strong acid, if it reacts slowly then it is a weak acid.
2) Measure the pH with a universal indicator; if they have the same concentration
then the strong acid will have a lower pH.