Moles and Tritation

Question 1

What is the ‘mole’?

Answer 1

Just a number

6.023 * 10²³

Question 2

What is the concentration of a solution measured in?

Answer 2

moles per dm³ (moles per litre)

OR grams per dm³

Question 3

The more solute you dissolve in a given [ ], the more crowded the soltute [ ] are and the more [ ] the solution

Answer 3

volume
molecules
concentrated

Question 4

What are titrations used for?

Answer 4

To find out exactly how much acid is needed to neutralise a quantity of alkali (or vice versa)

Question 5

Which indicator should you use for titrations? Why?

Answer 5

Phenolphthalein or Methyl orange

You don’t use universal indicator because it changes colour gradually and you want a definite colour change.

Question 6

Describe the colours (and colour changes) of th indicators

Answer 6

Phenolphthalein is pink in alkalis but colourless in acids

Methyl orange is yellow in alkalis but red in acids.

Question 7

Describe the process of titration

Answer 7

This process can be used for alkali and acids in either order.

1) Place some alkali in a flask with some indicator
2) Add the acid a bit at a time to the alkali using a burette - giving the flask a regular swirl
3) The indicator changes colour when all the alkali has been neutralised
4) Record the amount of acid used to neutralise the alkali.
5) Repeat the process at least 3 times and calculate an average (mean) of your results