Redox Titrations Flashcards

1
Q

Standard Solution

A

A solution of known concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Properties of a primary standard

A

Pure
Water soluble
Solid
High molecular mass
Not oxidised by air
Does not effloresce (lose water of crystallisation)
Does not deliquesce (absorb water from air)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is it necessary to dilute sulfuric acid when preparing from hydrated ammonium iron(II) sulfate

A

To prevent air oxidation of the Fe2+ in solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is it necessary to add more dilute sulfuric acid to each 25.0 cm3 portion of hydrated ammonium iron(II) sulfate

A

To ensure MnO4– reduces to colourless Mn2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Colour Change of hydrated ammonium iron(II) sulfate

A

Purple to faint permanent pink colour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is iodine brought into aqueous solution

A

Reacted with potassium iodide (KI)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Indicator for Iodine

A

Starch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When is the indicator added

A

When the solution in conical flask is light yellow near the end point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Colour Change of Starch in Iodine

A

Blue/Black to Colourless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why distilled water instead of deionised water is used

A

Deionised water could contain non-ionic substances that could be oxidised or reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Colour Change of Bleach Titration

A

Red/brown to colourless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why excess Potassium Iodide was used in Bleach Titration

A

So all the hypochlorite has reacted so the max iodine is produced
To keep the iodine in solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Indicator for Bleach Titration

A

Starch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is used to standardise the potassium manganate(VII) solution

A

ammonium iron(II) sulfate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is some dilute sulfuric acid added to the iron tablets

A

To prevent iron (II) being oxidised by air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is additional dilute sulfuric acid must be added to the iron titration

A

To ensure reduction of MnO4– to Mn2+

To prevent formation of Mn4+

17
Q

What must be added to pure iodine bring it into

aqueous solution

A

Potassium iodide

18
Q

Colour change of potassium iodide

A

Red/brown to light yellow to blue/black to colourless