Acid-Metal Reaction
Generalised Formula
- You can remember this formula by the acronym “MASH” (Metal + Acid → Salt + Hydrogen Gas).
- A salt is an ionic compound that consists of a negative (anion) and positive ion (cation).
- The positively charged ion comes from the metal.
- The negatively charged ion comes from the acid.
- You can remember this by remembering that acid is bad and metal is good.
Acids to Salts Chart
Acids → Salts
When an acid forms a salt, it makes different types of salts depending on the acid used.
| Acid | Salt |
|---|---|
| Hydrochloric acid | Chlorine salts |
| Sulphuric acid | Sulphites |
| Nitric acid | Nitrates |
| Carbonic acid | Carbonates |
Displacement Reactions
What type of reaction is a acid-metal reaction?
An acid-metal reaction is a displacement reaction, which means the less reactive element is substituted for the more reactive element.
Example Acid-Metal Reaction
- In an acid-metal reaction, we can see that the metal displaces the hydrogen from the solution.
- As this happens, the metal becomes ionic and the hydrogen becomes a gas.
Activity Series of Metals
Reactivity in Displacement Reactions
- More reactive species will displace less reactive species.
- This is based on the Activity Series of Metals, where metals are charted in terms of most to least reactive.
- The difference in reactivity will drive the rate of reaction.
| Most to Least Reactive | Symbol |
|---|---|
| Potassium | |
| Sodium | |
| Calcium | |
| Magnesium | |
| Aluminium | |
| Zinc | |
| Iron | |
| Tin | |
| Lead | |
| Hydrogen | |
| Copper | |
| Mercury | |
| Silver | |
| Gold |
Pop Test
- In order to test if hydrogen gas is made during an acid metal reaction, you can do the following.
- Start by putting an acid and metal in a test tube.
- Then, hold a burning wooden splint to the mouth of the test tube.
- If a pop occurs, hydrogen gas is produced as it will explode and make a ‘pop’ sound.