Chapter 10, Problem 170A

Interpretation Introduction

Interpretation:

Percentage composition of Vitamin E needs to be calculated.

Concept introduction:

One molecule of Vitamin E (C₂₉H₅₀O₂) contains 29 carbon atoms, 50 hydrogen atoms and 2 oxygen atoms.

The percentage of an element in a compound can be calculated as follows:

Percentage of an element in a compound $\text{=}\frac{\text{Number of atom}\times \text{Atomic mass of the element}}{\text{Molar mass of the compound}}\times 100\%$

Answer to Problem 170A

Vitamin E contains 80.93 % C, 11.63 % H and 7.44 % O.

Explanation of Solution

Molar mass of Vitamin E (C₂₉H₅₀O₂) is 430 g.

Atomic mass of C, H and O are 12 amu, 1 g and 16 amu respectively.

% of C in C₂₉H₅₀O₂$\text{=}\frac{29\times 12}{430}\times 100\%=\frac{34800}{430}\%=80.93\%$

% of H in C₂₉H₅₀O₂$\text{=}\frac{50\times 1}{430}\times 100\%=\frac{5000}{430}\%=11.63\%$

% of O in C₂₉H₅₀O₂$\text{=}\frac{2\times 16}{430}\times 100\%=\frac{3200}{430}\%=7.44\%$

Conclusion

Thus, in vitamin E there are 80.93 % C, 11.63 % H and 7.44 % O.