Practicals

Question 1

Steps of titration

Answer 1

• Wash burette using acid and then water
• Fill burette to 100cm’ with acid with the meniscus’ base on the 100cm line
• Use 25cm’ pipette to add 25cm of alkali into a conical flask, drawing alkali into the pipette using a pipette filler
• Add a few drops of a suitable indicator to the conical flask (eg: phenolphthalein which is pink when alkaline and colourless when acidic)
• Add acid from burette to alkali until end-point is reached (when solution goes colourless)
• The titre (volume of acid needed to exactly neutralise the acid) is the difference between the first (100cm’) and second readings on the burette)
• Repeat the experiment until you get concordant results

Question 2

What are concordant results

Answer 2

• results within 0.2 of each other

Question 3

Why do we use a white tile in titration

Answer 3

• to see colour change more clearly

Question 4

Why we use excess base in an excess base practical

Answer 4

• so all acid reacts completely

Question 5

Crystallisation following titration (and generally) TEMPLATE (4)

Answer 5

• heat until crystallisation point is reached
• cool and leave to crystallize
• pour off any excess liquid
• leave in warm oven to dry