[OrganicSynthesis]

13. Flutamide (Eulexin) is an important organic compound containing
three fluorine atoms in each molecule. It is used in the treatment of
prostate cancer. An analytical chemist extracted flutamide from a
commercial tablet weighing 203.21 mg leaving a residue (containing
non-medicinal ingredients) that weighed 128.23 mg. Elemental analysis
of the extracted flutamide revealed the presence of 15.47 mg of
fluorine. What is the molar mass (in g mol–1) of flutamide?

A. 232.8
B. 254.5
C. 276.2
D. 286.9
E. 303.1

I feel quite stumped on this question. It is a question from a past competition, and the answer is C.

The progress I have made so far is that the mass of the flutamide is 75.98mg, with 15.47mg of it being fluorine. Otherwise, I can't seem to make the logical next step. Anyone feel like pushing me in the right direction?

[UG]

I feel quite stumped on this question. It is a question from a past competition, and the answer is C.

The progress I have made so far is that the mass of the flutamide is 75.98mg, with 15.47mg of it being fluorine. Otherwise, I can't seem to make the logical next step. Anyone feel like pushing me in the right direction?

Calculate the number of moles of fluorine in 15.47 mg. How many molecules of F are in one flutamide molecule. How does knowing these two pieces of information allow you to work out the number of moles of flutamide and then the molar mass? Have a think.

[OrganicSynthesis]

Oh! This makes perfect sense now.

I found the number of moles of Fluorine

n = 15.47/(3)(19)

Then I just plugged it into the molar mass formula

M = (3)(19)(75.98)/15.47

The closest answer is C

Thank you very much!

[UG]

Haha, glad to help you out. I know all about tricky questions  although probably not as much as I should