methyl salicylate has mass percent composition of 63.2% C, 31.6% O and 5.26% H. The mass of one molecule of the compound is 2.53 x 10^-22 g. Determine the empirical formula and the molecular formula of methyl salicylate.

Question

anonymous · Answer

to find the EF
first find the ratio of n of moles in each compound:

since the % is given
we know that in 100g of methyl salicylate, we will have:
63.2g of C , 31.6g of O and 5.26g of H
n=m/M
so

n(c)=63.2/12.01    n(O)=31.6/16        n(H)=5.26/1.008
      =5.26 mol              =1.975 mol           =5.218 mol
ratio for C : O : H
       >>  2.66 : 1.975 : 2.642

divide everything by the smallest number to get the simplest ratio, we get
       >> 2.66 : 1 : 2.642   times everything by 3 to get whole number
       >> 8 : 3 : 8 (round off)

so EF= C8H8O3

m(EF)= 8x12.01+8x1.008+3x16
        =152.144g

m(MF)= 6.022x10^23 x 2.53x10^-22 (avagadro's number (number of atoms in one                                                                                   
                                                            mole) times the mass of one atom)
          =153.36g

thus MF=EF
        MF=C8H8O3