Acid — Science definition
A substance that increases hydrogen-ion activity in water; common dilute acidic solutions have pH below 7 near room temperature. Never identify experimental samples by taste.
Where it is taught
- Acids, Bases & pH — Chemistry, Physical Science: Matter, Forces & Energy, Grade 8
In use
Vinegar contains acetic acid and lemon juice contains citric acid.
Acids, Bases & pH
Questions using acid
Problem 1
Mixing an acid and a base together in a neutralization reaction produces water and a…
- gas only
- salt
- new acid
- new base
Answer and explanation
salt
Neutralization reactions between an acid and a base produce water plus a salt.
Problem 2
Will mixing equal volumes of any acid and base guarantee pH 7?
Answer and explanation
No. Concentrations, reacting amounts, and acid/base chemistry matter. Equal volumes alone cannot establish the final pH or product safety.
No. Concentrations, reacting amounts, and acid/base chemistry matter. Equal volumes alone cannot establish the final pH or product safety.
Response criteria
- Use the supplied conditions and relevant evidence.
- Explain the scientific mechanism or calculation.
- State a meaningful limitation or testable next step.
Problem 3
Mixing an acid with a base produces
- a stronger acid
- a salt and water
- only gas
- no change
Answer and explanation
a salt and water
Neutralisation forms a salt and water, moving the pH toward 7.