How do you calculate the percent by weight of each element in #Na_2SO_4#?

1 Answer
Sep 28, 2016

#"% Element"# #=# #"Mass of element"/"Molar mass of compound"xx100%#.

Explanation:

So for #%O#, we calculate #(4xx15.999*g*mol^-1)/(142.04*g*mol^-1)xx100%# #=# #45.05%#.

When you calculate the other percentages, you will find that the sum of the percentages adds to #100%#. Why should this be?