Question

Vitamin K5 contains 76.27% carbon by mass and has a molecular mass 173.21 g / mol­e. How many carbon atoms are in one K5 molecule ?

Answer 1

Given:

(i) Vitamin K5 contains 76.27% carbon by mass

(ii) Molar mass is 173.21 gm

To find:

(i) Number of Carbon atoms.

Solution:

Given, the molar mass is 173.21 gm

Again, it is said that carbon occupies 76.27% by  weight of the vitamin's mass.

So, mass of carbon = 76.27% of the total molar mass

= (76.27*173.21)/100 gm

= 132.11 gm

Carbon content is 132.11 gm

Again, 1 C atom weighs 12 gm.

So,

Number of carbon atoms = 132.11/12

= 11

Thus, the vitamin has 11 atoms of carbon