DP Chemistry (last assessment 2024)

Test builder »

Question 18N.3.hl.TZ0.9a

Select a Test
Date November 2018 Marks available [Maximum mark: 3] Reference code 18N.3.hl.TZ0.9a
Level hl Paper 3 Time zone TZ0
Command term Determine Question number a Adapted from N/A
a.
[Maximum mark: 3]
18N.3.hl.TZ0.9a

Lipids play several roles in our bodies.

(a)

The iodine number is the maximum mass of iodine that reacts with 100 g of an unsaturated compound.

Determine the iodine number of stearidonic acid, C17H27COOH.

[3]

Markscheme

ALTERNATIVE 1:

4 C=C bonds/4 carbon to carbon double bonds ✔

mass of iodine per mole of acid = «4 × 253.80 g mol–1 =» 1015.2 «g mol–1» ✔

iodine number « = 1015.2 g mo l − 1 276.46 g mo l − 1 × 100 » = 367 ✔

 

ALTERNATIVE 2:

4 C=C bonds/4 carbon to carbon double bonds ✔

« 100 g 276.46 g mo l − 1 × 4 =» 1.447 mol of I2 «reacts with 100 g»  ✔

iodine number «= 1.447 mol × 253.80 g mol–1» = 367 ✔

 

Award [3] for correct final answer.

Syllabus sections