Core Practical: Investigating pH Flashcards
All 6 cards in this deck
What should be used to measure the pH of a mixture most accurately in the core practical?
A pH meter (pH probe).
In the pH core practical, what are the steps for each addition of powdered calcium hydroxide to the acid?
e.g. one spatula added to 50 cm³ of dilute hydrochloric acid
- Add a measured mass of the solid to the fixed volume of acid.
- Stir the mixture so it is evenly spread and reacts fully.
- Measure the pH with a pH meter and repeat the additions.
What improvement to "add half a spatula of solid" gives more accurate results in the pH core practical?
Measure the mass of solid added / use a specified mass each time.
In the pH core practical, why does the pH level off once excess calcium hydroxide has been added?
All the acid has been neutralised and no more calcium hydroxide can dissolve, so the extra solid stays at the bottom and the pH stays constant.
In a balanced equation, what state symbols are used for powdered calcium hydroxide and for dilute hydrochloric acid?
Calcium hydroxide: ; hydrochloric acid: .
In the pH core practical, describe the shape of the graph of pH against the amount of base added to the acid.
The pH rises slowly at first, then rises steeply around neutral (pH 7), then levels off at a high pH.