Equal amounts in grams of following sub-stances were dissolved in equal amount of water. Which of these will have the highest boiling point ?

Equal amounts in grams of following sub-stances were dissolved in equa

1.	Equal amounts in grams of following sub-stances were dissolved in equal amount of water. Which of these will have the highest boiling point ?
Answer» Urea `(NH_(2) CONH_(2))` Glucose `(C_(6)H_(12)O_(6))` Sodium chloride ( NaCl ) Calcium chloride `(CaCl_(2))` Solution :The simple inspection of the question shows that (C) should be the correct choice because `CaCl_(2)` will give 3 mol of ions for 1 mol of `CaCl_(2)` DISSOLVED (assuming it to be completely dissociated). However, in the given question, the amounts are given in GRAMS. If we assume, `w` gram of all thesubstances are dissolved in 1000 g of solvent, then Molal conc. of NaCl `=(w)/(58.5)m` Molar conc. of `CaCl_(2)=(w)/(111)` m Since NaCl gives two mole of ions for one mole of it so that Molar concentration of ions in solution `=(w)/(58.5)xx2=0.034w` `CaCl_(2)` gives three moles of ions for 1 mol of it so that Molar conc. of ions in solution `=(w)/(111)xx3=0.027 w` Therefore, molal conc. of solute in NaCl solution is more than in `CaCl_(2)` solution.