5.4.2.5 Titrations

Question 1

How can the volumes of acid and alkali solutions that react with each other be measured?

Answer 1

• by titration
• using a suitable indicator

Question 2

How would you carry out a titration?

Answer 2

• wash burette using dilute hydrochloric acid and then water
• fill burette to 100cm3 with acid with the meniscus’ base on the 100cm3 line
• use 25cm3 pipette to add alkali into a conical flask, using a pipette filler
• add a few drops of a suitable indicator to the conical flask (e.g. phenolphthalein which is pink when alkaline and colourless when acidic)
• add acid from burette to alkali until end-point is reached (as shown by indicator)
• the titre is the difference between the first and second readings on the burette
• repeat the experiment to gain more precise results

Question 3

How do you convert dm3 into cm3?

Answer 3

• multiply by 1000

Question 4

How do you calculate concentration?

Answer 4

• conc = moles / vol