A sample of nitrogen gas #N_2# weighs 42.8 g. How many molecules of #N_2# are present in this sample? How many atoms of N do these represent?

1 Answer
Oct 20, 2017

This will be #9.20xx10^(23)# molecules of #N_2# and #1.80xx10^(24)# atoms of N.

Explanation:

The nitrogen gas has a molar mass of 28.0 g. We divide the given mass by this number to get the number of moles.

#42.8 -: 28.0 = 1.53# moles

Now, multiply the number of moles y Avogadros' number #6.02xx10^(23)#) to get the first answer:

#1.53xx(6.02xx10^(23))=9.20xx10^(23)# molecules of #N_2#

Since each molecule of #N_2# contains two atoms of N, the total number of atoms will be twice the above value, #1.80xx10^(24)# atoms of N.