Reactions of acids
Some general observations can be made during acid reactions:
- if a gas is produced, the observations is ‘bܲ’.
- if a solid such as a solid metal, base or carbonate reacts with the acid then the observation is ‘solid disappears and a solution is produced’.
- most acid reactions are exothermic – the observation is ‘heat released’. Exceptions – copper(II) oxide and sodium hydrogencarbonate with acid.
It is useful to know the colour of some compounds commonly reacted with acids to work out if a colour change has occurred.
| Substance | Colour |
| copper(II) oxide | black solid |
| copper(II) carbonate | green solid |
| hydrated copper(II) sulfate | blue crystals |
| copper(II) salts in solution | blue solution |
| group 1, group 2, aluminium and zinc compounds | white solids – if they dissolve in water they give colourless solutions |
| Substance | copper(II) oxide |
|---|---|
| Colour | black solid |
| Substance | copper(II) carbonate |
|---|---|
| Colour | green solid |
| Substance | hydrated copper(II) sulfate |
|---|---|
| Colour | blue crystals |
| Substance | copper(II) salts in solution |
|---|---|
| Colour | blue solution |
| Substance | group 1, group 2, aluminium and zinc compounds |
|---|---|
| Colour | white solids – if they dissolve in water they give colourless solutions |