Question

vitamin k5 contains 76.27% carbon by mass and has molecular mass 173.12 g mol-1 .how many carbon atoms are in ane k5 molecule

Answer 1

Given :

Mass % of carbon in vitamin $K_5$ = 76.27 %

Molecular mass of vitamin $K_5$ = 173.12 g

To Find :

No of carbon atoms present in one molecule vitamin $K_5$ = ?

Solution :

Since 76.27 % carbon by mass is present in the vitamin $K_5$ .

So, we can apply Unitary method here :

∴Mass of carbon present in 100 gm of vitamin $K_5$ = 76.27 gm

So, mass of carbon present in 1 gm of vitamin $K_5$ = $\frac{76.27}{100}$ gm

And mass of carbon present in 173.12 gm of vitamin $K_5$ i.e. in 1 molecule of vitamin $K_5$ = $\frac{76.27}{100}\times 173.12$ gm

                 = 132 gm

Now we know that the  gram atomic weight of carbon is 12 gm .

Since 1 molecule of vitamin $K_5$ contains 132 gm carbon , so no of carbon atoms in 1 molecule of the vitamin is = $\frac{132}{12}= 11$

Hence , in 1 molecule of this vitamin 11 carbon atoms are present .

Answer 2

Explanation:

76.27/100×173.21 = 132.21

atomic weight of carbon =12

132.21/12=11