Acids, bases and salts
Every day we use a multitude of acids, bases and salts.
The properties of acids and bases
Acids are compounds containing hydrogen that can be replaced by a metal, form hydrogen ions (H+).
Bases, also called alkali, are compounds which can accept protons and
yield1 hydroxide ions (OH-).
The most common properties of acids and bases are the following:
- acids have a sour taste, while bases have a bitter taste;
– acids produce a painful sensation on the skin, while bases give a
slippery sensation;
– acids react with certain metals to produce hydrogen gas, while bases react with oils and greases;
– acids turn litmus paper red, while bases turn litmus paper blue.
Salts and the neutralisation reaction
A salt is a compound obtained from the reaction of an acid with a base, which is called neutralisation reaction.
The pH scale
The pH scale is a numerical scale ranging from 0 to 14 used for measuring the acidity or alkalinity of a
solution.
Neutral which corresponds to 7.
Acidic when its pH value is smaller than 7, while it is basic or alkaline when it has a pH value larger than 7.
You use universal indicator paper to measure the pH of a solution, the colour of the paper will vary according
to its pH.