First chemistry (grades 7–8) · Grade 8
Acid meets base
ChemAI · Worksheet
NameClassDate
Aim
Add acid to a base until the pink colour disappears: neutralisation.
Before you start: what do you predict will happen? Why?
What you do
| Step | What I observed | |
|---|---|---|
| 1 | Add a few drops of phenolphthalein: the base turns pink. | |
| 2 | Add hydrochloric acid little by little until the pink just disappears. | |
| 3 | Turn on the pH meter: the solution is now close to neutral (pH 7). Acid + base → salt + water. |
Questions
- Write a word or symbol equation for one reaction you observed.
- Explain your most important observation using particles, ions or energy.
- Was your prediction right? What would you change to get a more reliable result?