There are lots of times we need to get rid of an acid completely. Stomach aches are often caused by too much acid in the stomach. If a pond is too acidic, life will not thrive in it.
Neutralising an acid with an alkali is one way of doing this, but there are others.
By looking at the patterns, we can predict what will happen for each type of reaction.
Acid + base, or acid + alkali
A base is a chemical which reacts with an acid to make a salt and water, and nothing else. The most common bases are metal oxides and metal hydroxides.
Some bases dissolve in water - these are given the special name alkali. Because alkalis dissolve in water, we can talk about them having a pH - the pH of alkalis is greater than 7.
No matter what the acid, base or alkali are, the reactions all follow the same pattern:
acid + base → salt + water
(for example, sulfuric acid + copper oxide → copper sulfate + water)
acid + alkali → salt + water
(for example, nitric acid + sodium hydroxide → sodium nitrate + water)
Acid + metal
We can also react an acid with a metal. The products are a salt + hydrogen gas:
acid + metal → salt + hydrogen
(for example, hydrochloric acid + magnesium → magnesium chloride + hydrogen)
Acid + carbonate
The final reaction you need to know is what happens when we react an acid with a carbonate compound.
acid + carbonate → salt + water + carbon dioxide
(for example, nitric acid + calcium carbonate → calcium nitrate + water + carbon dioxide
Naming the salt
All these reactions produce a salt. The rules for naming the salt are the same for all the reactions:
1. Look at the name of the non-acid (the alkali / base / carbonate / metal). There will be a metal mentioned in the name, usually as the first word.
Look at the examples in this Introduction - copper oxide, sodium hydroxide, magnesium, calcium carbonate. That metal name will be the metal in the name of the salt - look at the salts made in the examples - copper sulfate, sodium nitrate, magnesium chloride, calcium nitrate.
2. Now look at the acid used, which will tell you what type of salt is produced. There are three you are expected to know:
nitric acid, which produces nitrates
sulfuric acid, which produces sulfates
hydrochloric acid, which produces chlorides
Check the examples again - they all follow this rule.
And that's it! The name of the acid, and the metal added allow us to predict the salt form. The compound that the metal is in initially (alkali, base, pure metal, carbonate) tells us what else is produced.
Now let's move on to some questions.