How many molecules of sulfur trioxide are in 78.0 grams?

1 Answer
Apr 6, 2016

Answer:

Almost #6.022xx10^23# sulfur trioxide molecules.

Explanation:

By definition there are #6.022140857(74)×10^23# individual #SO_3# molecules in #80.066# #g# of this material. This represents the MOLAR MASS of sulfur trioxide.

To find the number of #SO_3# molecules, I simply divide the mass by the molar mass, to get a quantity in moles, and mulitply this number by #"Avogadro's number, "6.022140857(74)×10^23#, which is the number of molecules that have a #80.066*g# mass:

#(78.00*cancelg)/(80.0666*cancelg*cancel(mol^-1))# #xx# #6.022140857(74)×10^23*cancel(mol^-1)# #=# #??#