Acids are very dangerous when they are acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax. Dilute acids are less dangerous.
Organic acids are acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax - made from a group of atoms joined together. The acidity comes from the acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax in the -COOH group.
Inoganic acids come from mineral sources and are widely used in industry.
The measure of acidity is the acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax.
pH 1 is a strong acid, pH7 is neutral and pH 14 is a strong alkali.
Indicators are chemicals that change colour with acids and alkalis. Litmus is an example of an indicator.

Acids with metals.
Acids react with metals to make acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax and hydrogen gas.

acid + metal -> salt + acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax

but not all metals act like this. Metals acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax lead in the reactivity series do not form salts with acids.

Chemical etching uses acids.
The sheet of metal is covered in acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax.
The artist scrapes away some wax to make a drawing.
The plate is dipped in acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax which reacts with the metal where the wax has been scratched away.
The artist brushes away any hydrogen acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax.
The plate is removed and rinsed.
The plate is covered in acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax which flows into the grooves made by the acid.

Acids with metal oxides and metal hydroxides.
Acids react with metal oxides and hydroxides to make a acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax and water.

acid + metal oxide -> salt + acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax


Acids with metal carbonates
Acids react with metal carbonates to make a salt, water and acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax gas.

acid + metal carbonate -> salt + acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax + carbon dioxide


What makes something an acid?
Acids do not mix with water - they react with it to produce hydrogen acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax. All acids have hydrogen in their formula.
Strong acids ionise acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax in water, weak acids only ionise acidbelowbubblescarbon dioxidecompletelyconcentratedhydrogeninkionsmolecularpHsaltsaltsslightlywaterwax - only some of the molecules are ionised.