To calculate the molar masses of #Al(C_2H_3O_2)_3#, we must take all the molar mass of the elements present.
We have #C_2,H_3,O_2# three times, and one #Al# atom.
#C_2# has the molar mass of two carbon atoms, that is #12*2=24 \ "g/mol"#.
#H_3# has a molar mass of three hydrogen atoms, that is #1*3=3 \ "g/mol"#.
#O_2# is oxygen gas, and has the mass of two oxygen atoms, and that'll be #16*2=32 \ "g/mol"#.
So, the total mass of #C_2H_3O_2# will be #24+3+32=59 \ "g/mol"#. But, we have #(C_2H_3O_2)_3#. so we need to multiply the mass by #3#, and we get #59*3=177 \ "g/mol"#.
Final step is add the ,olar mass of aluminium, that is #27 \ "g/mol"#.
So, the total mass of this compound is #177+59=236 \ "g/mol"#.
