titration

what are the colours of phenolphthalein?

alkali - pink

acidic - colourless

what are the colours of methyl orange?

alkali - yellow

acidic - red

method for titration:

1. wash a burette using acid then water

2. fill the burette to 0cm3 with the meniscus’s base on the 0cm3 line with acid

3. using a 25cm3 glass pipette and a pipette filler, add 25cm3 of an alkali to a conical flask

4. add a few drops of indicator to the alkali (e.g. phenophthalein) which will turn pink (for p..)

5. slowly add acid from the burette to the alkali until the end-point is reached, which is when the indicator turns from pink to colourless

6. read the new value on the burette

7. calculate the titre - the difference in reading between the first and second values on the burette

8. use the first titre as a rough titre to indicate roughly what value you should be aiming for, and repeat the titration until you get concordant values

what are concordant values?

values that are within 0.2cm3 of each other