van't Hoff Factor — Prelims Questions

Which of the following aqueous solutions will have the highest boiling point? (Assume complete dissociation for electrolytes and equal molality for all solutions.) (A) 0.1 M Glucose (B) 0.1 M NaCl (C) 0.1 M $CaCl_2$ (D) 0.1 M $Al_2(SO_4)_3$

A 0.01 M aqueous solution of $K_3[Fe(CN)_6]$ has a freezing point of $-0.062^circ C$. Given $K_f$ for water is $1.86^circ C,kg,mol^{-1}$, calculate the van't Hoff factor (i) for the solution.

Acetic acid ($CH_3COOH$) associates to form a dimer in benzene. If 0.5 g of acetic acid is dissolved in 50 g of benzene, and the observed depression in freezing point is $0.45^circ C$, calculate the degree of association ($\beta$). ($K_f$ for benzene = $5.12^circ C,kg,mol^{-1}$, Molar mass of $CH_3COOH = 60,g/mol$)

What is the van't Hoff factor (i) for a 0.05 M solution of $BaCl_2$ if its degree of dissociation ($alpha$) is 0.8?

A solution of a non-volatile solute in water has a vapor pressure of 28 mm Hg at $25^circ C$. The vapor pressure of pure water at $25^circ C$ is 30 mm Hg. If the solute is an electrolyte that dissociates into 3 ions and its degree of dissociation is 0.75, what is the mole fraction of the solute?

Which of the following statements about the van't Hoff factor (i) is INCORRECT?

An aqueous solution contains 0.1 molal urea, 0.1 molal NaCl, and 0.05 molal $CaCl_2$. What is the total effective molality of particles in the solution?