If there are 100g of #NaClO_2# how would you calculate the percent composition by mass of each element in #NaClO_2#?

1 Answer
Mar 1, 2016

Answer:

You would calculate percent compositon by mass by first converting from grams of #NaClO_2# to mols of #NaClO_2# to find your mol to mol ratio of each element.

Explanation:

We are given 100g of #NaClO_2# and we want the mass of each individual element #(Na, Cl, O)#

Step 1

Convert 100g of #NaClO_2# to mols
#Na# = #22.98g#
#Cl# = #35.45g#
#O# = 16.00g * 2 = #32.00g#

#NaClO_2# = #(90.43g)/(1mol)#

#100g# #NaClO_2# * #(1mol)/(90.43g)# = #1.11# #mols# #NaClO_2#

Step 2

With mols of #NaClO_2#, we can now use our mol to mol ratio and find the percent composition by mass of the three elements

#1.11# #mols# #NaClO_2# #(1mol Na)/(1mol NaClO_2)# * #(22.98g Na)/(1mol Na)# = #25.5g# #Na#

#1.11# #mols# #NaClO_2# #(1mol Cl)/(1mol NaClO_2)# * #(35.45g Cl)/(1mol Cl)# = #39.3g# #Cl#

#1.11# #mols# #NaClO_2# #(2mol O)/(1mol NaClO_2)# * #(16.0g O)/(1mol O)# = #35.5g# #O#

The answer comes out to 100.3g total, but this is purely from sig figs