Flashcards in 23.2 - Manganate (VII) redox titrations Deck (11):
Describe how you would set up a manganate (VII) titration
1) Standard solution of KMnO4 added to burette
2) Add measured volume of solution being analysed to conical flask
3) Add an excess of H2SO4
What do you add to the burette in manganate (VII) titrations?
Standard solution of KMnO4
Why is H2SO4 added to the conical flask in manganate (VII) titrations?
To provide the H+ ions required for the reduction of MnO4- ions
Is an indicator used in manganate (VII) titrations? Why?
The reaction is self-indicating
What is the colour that indicates the end point of the manganate (VII) titration?
Permanent pale pink colour
What does a permanent pink colour indicate?
Indicates that there is an excess of MnO4- ions present
What is the colour change involved in manganate (VII) titrations?
Purple --> pale pink
Why is the top of the meniscus recorded, not the bottom?
Because KMnO4 is a deep purple colour so it is difficult to see the bottom of the meniscus through the intense colour
Which titres are used when calculating the mean?
2 concordant titres
Titre = 22.30 cm3
Each burette reading had an uncertainty of 0.05%
Calculate the % uncertainty
0.05 x 2 / 22.30