Food Analysis - Iodine Value of Lipids Prac

Question 1

Iodine value?

Answer 1

degree unsaturation

Question 2

Iodine value of olive oil?

Answer 2

79 - 88

Question 3

Iodine value of beeswax

Answer 3

8 - 11

Question 4

Iodine is not absorbed from aqueous sol’n - what do?

Answer 4

• use sol’n of iodine monochloride (ICl)

Question 5

Wij’s soln

Answer 5

ICl dissolved in Chloroform + glacial acetic acid

Question 6

What was the percentage of oil per 100 mL chloroform soln?

Answer 6

3 %

Question 7

Molarity of Na2SO3

Answer 7

.1000

Question 8

X =

Answer 8

blank titration in mL

Question 9

y =

Answer 9

titration in presence of fat in mL

Question 10

A

Answer 10

number of grams of oil per 100 g

Question 11

how many moles of S2O3 reacts with iodine?

Answer 11

2

Question 12

What do you put in the three erlenmeyer flasks?

Answer 12

two contain 15 mL of the lipid sample, and one contains a 15 mL chloroform blank. All three contain (after addition) 25 mLs of Wij’s sol’n

Question 13

After adding Wij’s - what do?

Answer 13

Cover flasks with parafilm & mix - place in dark cupboard for hour

Question 14

After 1 hour?

Answer 14

add 10 mL of 10% KI and distilled water to make vol to 100 mL

Question 15

Titrate with?

Answer 15

.1000 M Na2SO3

Question 16

Titrate to?

Answer 16

Pale yellow colour

Question 17

How many drops of starch added?

Answer 17

4 - 5 drops

Question 18

What colour after starch?

Answer 18

Blue

Question 19

End point following addition of starch?

Answer 19

colourless