Question

How many grams of disulfur decafluoride must be weighed out to get a sample of disulfur decafluoride that contains 13.4 g of fluorine ?

Answer 1

Molar mass of F = 19 g/mol

mass(F)= 13.4 g

use:

number of mol of F,

n = mass of F/molar mass of F

=(13.4 g)/(19 g/mol)

= 0.7053 mol

This is number of moles of F

one mole of S2F10 contains 10 mole of F

use:

number of moles of S2F10 = number of moles of S2F10 / 10

= 0.7053 / 10

= 7.053*10^-2

Molar mass of S2F10,

MM = 2*MM(S) + 10*MM(F)

= 2*32.07 + 10*19.0

= 254.14 g/mol

use:

mass of S2F10,

m = number of mol * molar mass

= 7.053*10^-2 mol * 2.541*10^2 g/mol

= 17.92 g

Answer: 17.9 g