core practical 11: redox titrations Flashcards
(9 cards)
1
Q
usual reactants
A
fe 2+ awith mno4 -
2
Q
why is no indicator needed?
A
self indicating due to colour change of the manganate
3
Q
mno4- is
A
purple
4
Q
mn2+ is
A
(pale pink)
colourless
5
Q
why do u need an acid
A
to provide h+ for mno4- to mn2+
6
Q
what acid to use
A
- dilute sulfuric acid
7
Q
if insufficient volume of acid used, or a weak acid like ethanoic acid?
A
- mno4- is only reduced to mno2 INSTEAD of mn2+
- which is brown, so masks the colour change
- so larger volume of manganate would be used
8
Q
why not use HCl?
A
- mno4 - would OXIDISE the cl- to cl2
- ref the e cell
- greater titre
9
Q
why not use hno3
A
- would oxidise fe2+ to fe 3+
- reference e cell
- SMALLER TITRE
