U4-4-2 - Redox and Complexometric Titrations

Question 1

What is an advantage of using potassium permanganate in titrations?

Answer 1

Reactions are self-indicating (endpoint is purple)

Question 2

What indicator can be used if iodine is produced during a reaction?

Answer 2

Starch (endpoint is blue/black)

Question 3

What type of ions can be determined using complexometric titration?

Answer 3

Metal ions

Question 4

Common reagent in complexometric titrations

Answer 4

EDTA

Question 5

Molar ratio of metal ions : EDTA

Answer 5

1 : 1

(EDTA is hexadentate, can only bind to 1 metal ion)

Question 6

A titration is carried out using a 50 cm³ burette, but the titre value is only 6.0 cm³.

What can be done to decrease the uncertainty in the titre value?

Answer 6

• Titrate a larger sample (titre value will increase)
• Use a less concentrated standard solution (prepare a lower conc. or dilute)
• Use a micro-burette (10 cm³ or less).

Question 7

A titration is carried out to determine the content of vitamin C in fruit juice.

What can be used as a control experiment?

Answer 7

Carry out a titration with a known mass/concentration of pure vitamin C.

(control experiment = use pure substance)