RP 9 - Investigating pH changes Flashcards
1
Q
What’s an alkali?
A
A base that dissolves in water
2
Q
Why are acid-base indicators used?
A
To detect when a reaction reaches completion/becomes neutral, usually by the presence of a colour change
3
Q
Why does a pH meter need to be calibrated?
A
So that the pH values for each pH reading are accurate
4
Q
How can you investigate how a weak acid’s pH changes upon addition of strong base?
A
- Add 2 cm^3 of NaOH from a burette to ethanoic acid, in a conical flask
- Continue adding 2 cm^3 of NaOH, measuring the pH each time
5
Q
Why is it important to stir the resulting solution when investigating how a weak acid’s pH changes upon addition of strong base?
A
So all acid and base is thoroughly mixed, so the pH doesn’t significantly vary throughout the solution as this would give an inaccurate reading
6
Q
How would analyse the data obtained from investigating how a weak acid’s pH changes upon addition of strong base
A
- Plot a graph of measured pH values (y-axis) against volume of NaOH solution added (x-axis)
- Consider what the shape of the curve is
