5.1.3 - titration

Question 1

what is titration used to measure

Answer 1

the volume (or ‘titre’) of acid needed to neutralise a particular volume of alkali, or vice versa

Question 2

what pieces of equipment are used in titration

Answer 2

• volumetric pipette
• burette

Question 3

volumetric pipette:

Answer 3

• measures out 25cm^3 very accurately
• can’t measure out any other volume very well

Question 4

burette:

Answer 4

measures any volume to the nearest 0.05cm^3

Question 6

titration setup:

(assuming the acid is known and the alkali is unknown)

Answer 6

1) use a volumetric pipette to place 25cm^3 of the unknown alkali into a conical flask
2) add a few drops of either methyl orange or phenolphthalein indicator to the flask
3) fill a burette with known acid and clamp it above the conical flask

Question 7

why does universal indicator not work in titration

Answer 7

it changes colour too gradually

Question 8

titration usage:

(assuming the acid is known and the alkali is unknown)

Answer 8

4) measure the initial volume of known acid on the burette, to the nearest 0.05cm^3
5) use the burette to add acid into the conical flask drop-by-drop and swirling the flask
6) close the burette tap as soon as the colour in the conical flask changes
7) measure the final volume of known acid on the burette to the nearest 0.05cm^3
8) calculate titre (final volume - initial volume)
9) repeat to get concordant (within 0.2cm^3) titres

Question 9

what is the colouring like in a titration

Answer 9

the start colour will be the alkaline colour
the end colour will be the acidic colour
(because the last drop of acid always has a tiny bit more than is needed to neutralise)

Question 10

how to do titration calculations

Answer 10

check notes booklet