Question #4d8ee

1 Answer
Nov 19, 2015

#"201 g"#


The trick here is to get the chemical formula for this compound right. This will allow you to find its molar mass, and eventually its percent composition of sulfur.

So, how would you write the chemical formula for dinitrogen disulfide? As you know, Greek prefixes are used when naming covalent compounds.

In this case, the Greek prefix di-, which means two, tells you that you have two of each element in that molecule. So dinitrogen disulfide will contain

  • two nitrogen atoms
  • two sulfur atoms

Therefore, you can say that your compound's chemical formula is #"N"_2"S"_2#.

Now, in order to find its percent composition of sulfur, you need to know two things

  • the molar mass of dinitrogen disulfide, which is equal to #"92.144 g/mol"#
  • the molar mass of sulfur, which is equal to #"32.065 g/mol"#

Calculate the percent composition of sulfur by dividing the molar mass of both sulfur atoms by the molar mass of the compound, and multiplying the result by #100#

#"% S" = (2 xx 32.065color(red)(cancel(color(black)("g/mol"))))/(92.144color(red)(cancel(color(black)("g/mol")))) xx 100 = 69.6%#

This means that every #"100 g"# of dinitrogen disulfide will contain #"69.6 g"# of sulfur.

In your case, the #"289-g"# sample will contain

#289color(red)(cancel(color(black)("g N"_2"S"_2))) * "69.6 g S"/(100color(red)(cancel(color(black)("g N"_2"S"_2)))) = color(green)("201 g S")#

SIDE NOTE You'll sometimes see this compound written as disulfur dinitride, and having the chemical formula #"S"_2"N"_2#.

For the purposes of your problem, the answer will be the same regardless of what nomenclature you use.