The formula unit for ammonium dichromate is ##”(NH”_4)_2″Cr”_2″O”_7″##, and has a molar mass of ##252.07 “g/mol”##.
The ammonium ion, ##”NH”_4^+”##, is the cation, and its molar mass is ##18.039 “g/mol”##. Since there are two moles of ammonium cations in one mole of ammonium dichromate, we multiply ##18.039 “g/mol”xx2 ##, which is equal to ##36.078 “g/mol”##.
To find the percentage of ammonium cations in ammonium dichromate, divide the total mass of the ammonium cations by the molar mass of ammonium dichromate and multiply times 100.
##”%NH”_4^+=(36.078 “g/mol”)/(252.07 “g/mol”)xx100=14.313%##
