How do you calculate the mass percentage of different constituent elements in urea?

1 Answer
anor277
Sep 8, 2016

#"% element"# #=# #"Mass of element"/"Molar mass of element"xx100%#

Explanation:

For urea, #CO(NH_2)_2#, the molar mass is #60.06*g*mol^-1#.

And thus #"% nitrogen"#

#=# #(2xx14.01*g*mol^-1)/(60.06*g*mol^-1)xx100%=46.6%#

#"% oxygen"# #=# #??#

#"% hydrogen"# #=# #??#

You will know if you are right if all the percentages add up to #100%#. Why should this be so?

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