Experiment F: Anaylsis Of Vitamin C In Tablets And In Tang Flashcards

1
Q

What are the two objectives

Have to say chemical formula

A

Contents of vitamin C, C6H806 ( and potentially other acids will be determined in tablets and tang

Results will be compared with contents stated on label

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

What is vitamin c also called (2)

A

Ascorbic acid/ ascorbigen

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

What is scurvy

A

Lack of vitamin C

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

Why is vitamin C water soluble (2)

A
  • formation of hydrogen bonds between its (-OH) and
    (C double bonded to O) groups

-and the (-OH) of the solvent molecules

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

How many mg of vitamin C do multivitamins have

vitamin C tablets?

A

Multivitamins: at least 90mg

Tablets l: 250-500mg

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

What is an indicator in titration

A

Substance that changes colour in response to a chemical change

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

What does an indicator have

A

An endpoint that would correspond with the equivalence point for the reaction

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

What are the two titrations with

Have to say chemical formulas

A

1) KIO3, potassium iodate

2) NaOH, sodium hydroxide

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

What is the titration with KIO3, potassium iodate used for

A

To find the amount of vitamin C in the sample

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

Steps for titration with KIO3, potassium iodate (5)

A

1) KI, HCL, and a few drops of starch solution are added to sample

When solution is titrated:

2) iodate ion reacts with I- and H+ to form I2

IO3 - + 5I - + 6H+ —-> 3I2 + 3H2O

Each IO3 - added forms THREE I2

3) once formed, I2 is reduced immediately by vitamin C back to I-

————-

4) after all the vitamin C in the sample has been consumed, the I2 (from the addition of more update) reacts rapidly with I- to form the triiodide ion, I3 - (linear molecule)

I2 (aq) + I - (aq) —> I3 - (aq)

5) I3 - will reacted quickly with starch to form a blue-black starch-triiodide ion complex

Appearance of colour signals endpoint of titration

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

Explain titration with NaOH

A

After amount of vitamin C in tablet and Tang is determined by titration with iodate, the samples will be titrated using NaOH

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

List aspects of titration with NaOH (3)

A
  • only 1 OH group in vitamin C will react with hydroxide
  • the reaction with update is specific to t)3 ascorbate part of the vitamin C molecule
  • the reaction with NaOH will ALSO react with any sufficient acidic protons of any acid present
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What will the comparison of the titrations with KIO3 and NaOH show

A

Wether there are acids OTHER THAN vitamin C in the sample

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

Is temp intensive or extensive

A

Intensive

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

Why does it take LESS energy to raise the temp of metals compared to other elements

A

Metals are good heat conductors, so they retain heat well

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

Why does vitamin C dissolve in water

A

Hydrogen bonding

17
Q

How many OH groups does vitamin C have

A

4

18
Q

All of the limiting reactant put into the calorimeter ___ react

A

Must

19
Q

Calorimeter should be made of a good ______ material

A

Insulating