Techniques to identify molecules Flashcards

1
Q

What is the overall equation for an iodine-sodium thiosulfate titration?

A

2S203^(2-)(aq) + I2(aq) -> S4O6^(2-)(aq) + 2I^(1-)(aq)

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

What is reduced in an iodine-sodium thiosulfate titration?

A

Iodine I2 become 2 I^- ions

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

What is the ratio of sodium thiosulfate to iodine in the titration?

A

2:1

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

What is oxidised in an iodine-sodium thiosulfate titration?

A

Sodium thiosulfate ions are oxidised to tetrathionate ions.

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

What is the end point?

A

The point in a titration in which a definite observable change has occurred. Gives an estimate of the equivalence point but is not always accurate.

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

What is the equivalence point?

A

The point at which enough titrant has been added that the chemical reaction in the titrant mixture should be completed.

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

Why is a starch indicator used in an iodine-sodium thiosulfate titration?

A

To aid in identifying the end point. Starch is blue in the presence of I2, so when the reaction is completed, the point at which the solution becomes transparents is clearer than without starch.

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

How can moles of sodium thiosulfate be calculated in a titration?

A

use n=cv
the concentration of sodium thiosulfate multiplied by the volume of the titrant.

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

Is the iodine in the burette or the conical flask?

A

in this prac, the iodine was in the flask, and the sodium thiosulfate in the burette

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

What are some possible sources of error in a titration?

A
  • Inaccurate detection of the end-point.
  • Equipment not being rinsed properly and containing leftover chemicals.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the iodine number?

A

The mass of iodine in grams absorbed by 100 grams of the oil or fat.

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

What are the steps to finding the iodine number?

A
  1. find the mols of the oil
  2. multiples mols of oil by number of double bonds in the oil to find total mols of double bonds.
  3. mols of iodine = mols of double bonds, so therefore find mass of iodine and therefore iodine number
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly