Use the products to identify the reaction.
An acid and a hydroxide base produce water and a salt; their net ionic neutralisation equation is + OH⁻ → H₂O. A reactive metal with a suitable non-oxidising acid may produce hydrogen. Carbonate with excess acid produces carbon dioxide and water.
Use atom and charge balance rather than memorising an unbalanced pattern. Gas formation alone does not identify the gas: hydrogen and carbon dioxide require different evidence. Include state symbols and account for spectator ions when writing a net ionic equation.
Acid meets hydroxide
Explore the relationship
H⁺ + OH⁻ → H₂O, assuming complete reaction. The curve plateaus when hydroxide is exhausted.
Tap or focus a plotted point to read its values.
View plotted data as a table
| Series | Added hydrogen ions / mmol | Water formed / mmol |
|---|---|---|
| Water formed / mmol | 0 | 0 |
| Water formed / mmol | 0.2 | 0.2 |
| Water formed / mmol | 0.4 | 0.4 |
| Water formed / mmol | 0.6 | 0.6 |
| Water formed / mmol | 0.8 | 0.8 |
| Water formed / mmol | 1 | 1 |
| Water formed / mmol | 1.2 | 1.2 |
| Water formed / mmol | 1.4 | 1.4 |
| Water formed / mmol | 1.6 | 1.6 |
| Water formed / mmol | 1.8 | 1.8 |
| Water formed / mmol | 2 | 2 |
| Water formed / mmol | 2.2 | 2.2 |
| Water formed / mmol | 2.4 | 2.4 |
| Water formed / mmol | 2.6 | 2.6 |
| Water formed / mmol | 2.8 | 2.8 |
| Water formed / mmol | 3 | 3 |
| Water formed / mmol | 3.2 | 3.2 |
| Water formed / mmol | 3.4 | 3.4 |
| Water formed / mmol | 3.6 | 3.6 |
| Water formed / mmol | 3.8 | 3.8 |
| Water formed / mmol | 4 | 4 |
| Water formed / mmol | 4.2 | 4.2 |
| Water formed / mmol | 4.4 | 4.4 |
| Water formed / mmol | 4.6 | 4.6 |
| Water formed / mmol | 4.8 | 4.8 |
| Water formed / mmol | 5 | 5 |
| Water formed / mmol | 5.2 | 5 |
| Water formed / mmol | 5.4 | 5 |
| Water formed / mmol | 5.6 | 5 |
| Water formed / mmol | 5.8 | 5 |
| Water formed / mmol | 6 | 5 |
| Water formed / mmol | 6.2 | 5 |
| Water formed / mmol | 6.4 | 5 |
| Water formed / mmol | 6.6 | 5 |
| Water formed / mmol | 6.8 | 5 |
| Water formed / mmol | 7 | 5 |
| Water formed / mmol | 7.2 | 5 |
| Water formed / mmol | 7.4 | 5 |
| Water formed / mmol | 7.6 | 5 |
| Water formed / mmol | 7.8 | 5 |
| Water formed / mmol | 8 | 5 |
| Water formed / mmol | 8.2 | 5 |
| Water formed / mmol | 8.4 | 5 |
| Water formed / mmol | 8.6 | 5 |
| Water formed / mmol | 8.8 | 5 |
| Water formed / mmol | 9 | 5 |
| Water formed / mmol | 9.2 | 5 |
| Water formed / mmol | 9.4 | 5 |
| Water formed / mmol | 9.6 | 5 |
| Water formed / mmol | 9.8 | 5 |
| Water formed / mmol | 10 | 5 |
| Water formed / mmol | 10.2 | 5 |
| Water formed / mmol | 10.4 | 5 |
| Water formed / mmol | 10.6 | 5 |
| Water formed / mmol | 10.8 | 5 |
| Water formed / mmol | 11 | 5 |
| Water formed / mmol | 11.2 | 5 |
| Water formed / mmol | 11.4 | 5 |
| Water formed / mmol | 11.6 | 5 |
| Water formed / mmol | 11.8 | 5 |
| Water formed / mmol | 12 | 5 |
Explore: Add acid to a fixed amount of hydroxide and identify when one reactant is exhausted.
React magnesium with dilute hydrochloric acid.
- Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g).
- Net ionic: Mg(s) + (aq) → Mg²⁺(aq) + H₂(g).
Assumed knowledge
Balanced ionic equations.
Learning checkpoints & source
YOUR LEARNING CHECKPOINT- Balance reactions of acids with bases, metals and carbonates.
- Use observations to identify ions and products.