CP 2 ‐ Investigating pH (neutralisation)

Question 1

If you wanted a fixed volume of HCl for
an experiment, what is the best piece of
apparatus to use?

Answer 1

Volumetric Pipette

Greater accuracy than a measuring
cylinder

Question 2

How can you measure the pH of a solution?

Answer 2

Use a pH probe or add universal indicator and compare to
a colour chart

• Red: strong acid (pH 1)
• Yellow: weak acid
• Green: neutral (pH 7)
• Light blue: weak alkali
• Blue/purple: strong alkali (pH 14)

Question 3

What is a neutralisation reaction?

Answer 3

Hydrogen ions reacting with hydroxide

ions to form water

Question 4

When measuring the pH change of the combination
of two reactants why is it important to stir the mixture
after the reactants are combined?

Answer 4

To ensure a complete reaction and that
the pH is consistent throughout the
mixture

Question 5

How could an experiment measuring the pH using

universal indicator paper be improved?

Answer 5

Use a pH probe to get an accurate

reading

Question 6

Ca(OH)2
can be added to HCl for neutralisation. How
do you know that the HCl has been fully neutralised?

Answer 6

The pH should be pH 7 - neutral

Question 7

Ammonia solution is an alkali. What could be used to

show it is alkaline?

Answer 7

Either:

• Universal indicator paper turns blue
• High pH probe value around 11