### ZIMSEC O Level Combined Science Notes: Neutralisation/Salts

• The acidity and alkalinity of a solution can be represented on the pH scale
• If the pH is low i.e less than 7 then the solution is acidic
• If the pH is high i.e higher than 7 then the solution is alkaline
• If a solution has a pH of 7 then the solution is neutral
• This means it is neither acidic or alkaline
• The pH of an acid increases if a base is added to it
• At some point if, we continue to add the base, the solution becomes neutral
• When the base is added to the acid the acidity of of the solution decreases while its pH increases
• When the mixture reaches a pH of 7  just enough of the base solution will have been added to the acid to neutralise the acid
• Neutralisation is a reaction where an acid reacts with an alkali(base) to form a neutral solution of a salt and water.
• When the acid is neutralised salt and water is formed
• The word salt is used to refer to one of the by products formed when an acid and base react
• Sodium chloride otherwise known as table salt or common salt is just one of the many types of salt
• Other examples of salts are: copper sulphate, potassium permanganate, magnesium sulphate etc.
• The word equation for neutralisation is:
• $\text{base+acid}\rightarrow\text{salt+water}$
• Not all bases are soluble in water as a result
• Some metal oxides do not form alkaline solutions
• Still these insoluble bases react with acids to form a solution of salt and water
• Salt is always a byproduct of the neutralisation process

To access more topics go to the Combined Science Notes page,

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