How do you calculate the percent composition by mass of each element in #Al(OH_)3#?

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Answer 1 · 2018-05-17T15:27:41

#Al = 34.62%#

#O = 61.54%#

#H = 3.85%#

The Percentage Composition by Mass of Each Element is indicated by :-

#"Molar mass of The Element"/"Molar Weight of the Total Compound" xx 100%#

So, The Molar Weight of the Total Compound = #{27 + 3 xx (16 + 1)}# #g# #mol^-1# = #(27 + 51)# #g# #mol^-1# = #78# #g# #mol^-1#

So, Percentage Composition of Aluminium = #27/78 xx 100% = 34.62%# (approx.)

Percentage Composition of Oxygen = #(3 xx 16)/78 xx 100% = 61.54%# (approx.)

And Percentage Composition of Hydrogen = #(3 xx 1)/78 xx 100% = 3.85%# (approx.)