Acids in the laboratory

Dilute acids

Strong acids such as hydrochloric acid, sulfuric acid and nitric acid are laboratory acids that have been mixed with a lot of water before putting them out for use. Their bottles are labelled with a warning symbol to show that they can irritate your skin or cause some other minor harm to health.

Old 'irritant' symbol alongside new 'warning' symbol.

This means that if any of them makes contact with your skin, it may become red or blistered. You must wash off any spills with plenty of water, otherwise your skin may soon feel as if it is burning.

Concentrated acids

Concentrated acids are acids mixed with very little water. They are much more dangerous than dilute acids. Concentrated acids are corrosive. They can attack metals and destroy skin if spilled. Their bottles are labelled with a warning symbol to show that they are corrosive.

Old 'corrosive' symbol alongside new one.

Weak acids

Laboratory acids are far too dangerous to taste, but you will have swallowed some dilute weak acids. Acids have a sour taste, like vinegar, which contains ethanoic acid, and lemons, which contain citric acid. These are safe to use in food, but they can still hurt if they get into a cut or into your eyes. The table shows these and other acids found in food:

Table to illustrate various sources of acids: ethanoic acid from vinegar, carbonic acid from fizzy drinks, tannic acid from tea, ascorbic acid from vitamin C in oranges, citric acid from lemons