Practical P1 - Titrations

Question 1

what are titrations used for

Answer 1

to find out what volume of acid is needed to neutralise a measured volume of alkali

Question 2

what equipment is used in titrations
3 points

Answer 2

1) pipette
2) burette with scale
3) conical flask

Question 3

whats the method for doing a titration
6 points

Answer 3

1) if you want to find the concentration of some alkali, use a pipette and pipette filler to add a set volume of alkali to a conical flask
2) then add 2 or 3 drops of indicator to it, use a funnel to fill a burette with some acid with a known concentration of acid and record its initial volume
3) do this below eye level in case acid spills over - and wear safety glasses
4) use a burette to add the acid to the alkali a bit at a time, regularly swirling the flask
5) when the colour change is about to be reached add the acid drop by drop, when the colour changes stop adding it completely, it’s been neutralised
6) record the final volume of acid and calculate the volume used to neutralise the alkali

Question 4

what should you do after the titration
2 points

Answer 4

1) repeat and find a mean volume
2) increases accuracy of titration and you spot any anomalous results

Question 5

what indicators should you use in titrations
4 points

Answer 5

1) single indicators, to show a sudden colour change instead of universal indicators which turns a variety of colours
2) phenolphthalein - colourless in acid -> pink in alkali
3) litmus - red in acid -> blue in alkali
4) methyl - red in acid -> yellow in alkali