Question

Paclitaxel, which is extracted from the Pacific yew tree Taxus brevifolia, has antitumor activity for ovarian and breast cancer. It is sold under the trade name Taxol. On analysis, its mass percentage composition is 66.11% C, 6.02% H, and 1.64% N, with the balance being oxygen. What is the empirical formula of paclitaxel?

Answer 1

Answer:

The empirical formula is = $C_{47}H_{51}NO_{14}$

Explanation:

$Moles =\frac {Given\ mass}{Molar\ mass}$

% of C = 66.11  

Molar mass of C = 12.0107 g/mol

% moles of C = 66.11 / 12.0107 = 5.5043

% of H = 6.02  

Molar mass of H = 1.00784 g/mol

% moles of H = 6.02 / 1.00784= 5.973

% of N = 1.64

Molar mass of N = 14.0067 g/mol

% moles of N = 1.64 / 14.0067= 0.1171

Given that the Paclitaxel contains C, H, N and O. So,

% of O = 100% - % of C - % of H - % of N = 100 - 66.11 - 6.02 - 1.64  = 26.23 %

Molar mass of O = 15.999 g/mol

% moles of O = 26.23 / 15.999 = 1.6395

Taking the simplest ratio for C, H, N and O as:

5.5043 : 5.973 : 0.1171  : 1.6395

= 47 : 51 : 1  : 14

The empirical formula is = $C_{47}H_{51}NO_{14}$