Chemistry: Sulfur and Fluorine reaction?

Question

Sulfur and Fluorine react in a combination reaction to produce sulfur hexafluoride:

In a particular experiment, the percent yield is 79.0%. This means that a 7.90g sample of fluorine yields ______g of SF6 in the presence of excess sulfur.

A) 30.3

B) 10.1

C) 7.99

D) 24.0

E) 0.110

Answer 1

S + 3 F2 >> SF6

Moles F2 = 7.90 g / 37.9968 g/mol = 0.208

Moles SF6 = 0.208/3 =0.0693 ( theoretical yield)

0.0693 x 79.0 / 100 =0.0547 ( actual yield)

Mass = 0.0547 mol x 146.0564 g/mol = 7.99 g

C) is your answer