Strong acid

In chemistry, a strong acid is an acid which ionises (splits) completely in a solution of water. It always loses a proton (A H₊ when put in water. A weak acid does not always lose a proton, though; It can lose its proton, but not all the time^[source?] They also have a very low pH, usually between 1 and 3. Many strong acids have a negative pKa value, which means they are very strong.

The six common strong acids are:

1. Hydrochloric acid HCl
2. Hydrobromic acid HBr
3. Hydroiodic acid HI
4. Sulfuric acid H₂SO₄
5. Perchloric acid HClO₄
6. p-Toluenesulfonic acid: an organic soluble strong acid

Almost strong acids include:

1. Nitric acid HNO₃
2. Chloric acid HClO₃