Question

A mixture of NaI and NaCl,when heated with H2SO4, produced the same weight of sodium sulphate as that of original mixture.Calculate percentage of NaI in the mixture.

Answer 1

Hi,

take a basis first take a 100 g of mixture it resuts 100 g of Na2SO4

what is the mass percent of Na in that molecule

molecular weight = 2*Na+S+4*O = 2*23+32+4*16 = 142g/mol

Na = 2*23=46 g/mol

Na/Na2SO4= 46/142 =0.324

mass of sodium in the final molecule = 100*0.324 =32.4g

now the rest was the I+Cl before heating =100-32.4 = 67.6 g

at the begining u have 67.6 g of I and Cl

what are the molecular weight of I and Cl
I = 126.9 g/mol
Cl=35.45 g/mol

after this point u should find what percent they ccombine to give those calculated amounts

let say x mole to NaI and y mole to NaCl

x*I+y*Cl = 67.6 = x*126.9+y*35.45

x*Na+x*Na = 32.4 = (x+y)*23


u end up with two eqns with two unknowns
126.9x+35.45y = 67.6
23x+23y = 32.4

solve x and y to get their number of moles at the beginning then calculate their molar or weight percentages

Hope it helps...