Core Practical: Investigating pH Flashcards
All 5 cards in this deck
What are the steps in the core practical investigating the change in pH when a base is added to acid?
e.g. adding powdered calcium hydroxide to dilute hydrochloric acid- Measure a fixed volume of acid with a pipette or burette into a beaker and record its pH.
- Add one weighed spatula of calcium hydroxide and stir.
- Measure the pH, then repeat the additions until the pH stops changing.
How is the pH found when a drop of the mixture is placed on universal indicator paper?
Observe the colour produced and compare it with the pH chart/scale.
Which piece of equipment measures pH more accurately than universal indicator paper?
A pH meter (pH probe).
Why is the mixture stirred after each addition of the powdered base?
To mix it evenly so the base reacts/dissolves and the pH is uniform.
What happens to the hydrogen ions as calcium hydroxide is added to hydrochloric acid?
They are neutralised by hydroxide ions, so their concentration falls and the pH rises.