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

Question 1

What are the two objectives

Have to say chemical formula

Answer 1

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

Question 2

What is vitamin c also called (2)

Answer 2

Ascorbic acid/ ascorbigen

Question 3

What is scurvy

Answer 3

Lack of vitamin C

Question 4

Why is vitamin C water soluble (2)

Answer 4

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

-and the (-OH) of the solvent molecules

Question 5

How many mg of vitamin C do multivitamins have

vitamin C tablets?

Answer 5

Multivitamins: at least 90mg

Tablets l: 250-500mg

Question 6

What is an indicator in titration

Answer 6

Substance that changes colour in response to a chemical change

Question 7

What does an indicator have

Answer 7

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

Question 8

What are the two titrations with

Have to say chemical formulas

Answer 8

1) KIO3, potassium iodate

2) NaOH, sodium hydroxide

Question 9

What is the titration with KIO3, potassium iodate used for

Answer 9

To find the amount of vitamin C in the sample

Question 10

Steps for titration with KIO3, potassium iodate (5)

Answer 10

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

Question 11

Explain titration with NaOH

Answer 11

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

Question 12

List aspects of titration with NaOH (3)

Answer 12

• 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

Question 13

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

Answer 13

Wether there are acids OTHER THAN vitamin C in the sample

Question 14

Is temp intensive or extensive

Answer 14

Intensive

Question 15

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

Answer 15

Metals are good heat conductors, so they retain heat well

Question 16

Why does vitamin C dissolve in water

Answer 16

Hydrogen bonding

Question 17

How many OH groups does vitamin C have

Answer 17

4

Question 18

All of the limiting reactant put into the calorimeter ___ react

Answer 18

Must

Question 19

Calorimeter should be made of a good ______ material

Answer 19

Insulating