van't Hoff factor: dissociation and association

37 questions on van't Hoff factor: dissociation and association from the Solutions and Colligative Properties chapter: 7 NEET level, 13 JEE Main, 17 JEE Advanced. Each one opens with its answer and solution.

• The van't Hoff factor i for a 0.01 m aqueous solution of Na2SO4, assuming complete dissociation, is NEET level
• Ethanoic (acetic) acid dimerises in benzene. The van't Hoff factor i of its solution in benzene is therefore NEET level
• The van't Hoff factor i is defined as NEET level
• The van't Hoff factor of CaCl2 in a dilute aqueous solution is found to be 2.50. Using i = 1 + (n-1)alpha where n is the number of ions per formula unit, the de... JEE Main level
• A 0.20 m aqueous solution of K2SO4 is 80% dissociated (i = 1 + (n-1)alpha). With K_f = 1.86 K kg mol^-1, the depression of freezing point is JEE Main level
• Ethanoic acid (normal molar mass 60 g mol^-1) is dissolved in benzene, where it associates as 2 A leftharpoons A_2. The molar mass determined from freezing poin... JEE Main level
• A 0.50 m aqueous NaCl solution has an experimentally determined van't Hoff factor i = 1.85. With K_b = 0.52 K kg mol^-1 and the normal boiling point of water 10... JEE Main level
• A 0.50 m aqueous solution of a salt AB2 (giving three ions per formula unit, i = 1 + 2alpha) freezes at -1.395 degC. Take K_f = 1.86 K kg mol^-1. Find the degre... JEE Main level
• Which of the following solutions has a van't Hoff factor i greater than 1? (Consider dilute solutions in the solvent stated.) JEE Main level
• Assume complete dissociation of electrolytes and ideal behaviour in water. Which of the following statements is/are correct? JEE Main level
• A solution is made by dissolving 0.10 mol of NaCl and 0.050 mol of CaCl2 in 500 g of water. Assuming complete dissociation of both salts and K_f = 1.86 K kg mol... JEE Advanced level
• A weak monobasic acid HA (molar mass 60 g mol^-1), 3.0 g, is dissolved in 250 g of water and the boiling point rises by 0.1248 K (K_b = 0.52 K kg mol^-1). Using... JEE Advanced level
• A 0.100 m aqueous solution of a weak monobasic acid HA freezes at -0.2046 degC (K_f = 1.86 K kg mol^-1). Treat molality as equal to molar concentration and use ... JEE Advanced level
• 1.22 g of benzoic acid (molar mass 122 g mol^-1) is dissolved in 50 g of benzene (K_f = 5.12 K kg mol^-1). The freezing point falls by 0.614 K. The acid dimeris... JEE Advanced level
• 1.645 g of K3[Fe(CN)6] (molar mass 329 g mol^-1) is dissolved in water to make 500 mL of solution. The salt is 90% dissociated (K3[Fe(CN)6] -> 3 K+ + [Fe(CN)6]^... JEE Advanced level
• A 0.20 m aqueous solution of a weak acid HA is 10% ionised (HA <=> H+ + A-, K_f = 1.86 K kg mol^-1). Which of the following statements is/are correct? JEE Advanced level
• A solute A associates in benzene as 2A leftharpoons A_2 with degree of association beta, so i = 1 - beta/2. Which of the following statements is/are correct? JEE Advanced level
• An aqueous 0.050 m solution of Na2SO4 freezes at -0.270 degC (K_f = 1.86, K_b = 0.52 K kg mol^-1; i = 1 + 2alpha). Which of the following statements is/are corr... JEE Advanced level
• The van't Hoff factor i for a 0.1 mol kg^-1 aqueous solution of K2SO4, assuming complete dissociation, is NEET level
• A weak monobasic acid HA has K_a=1.0x10^-4. Use K_a=(Calpha^2)/(1-alpha) (solve the quadratic), molality approx molarity, i=1+alpha and K_f=1.86 K kg mol^-1. Co... JEE Advanced level
• A 0.50 mol kg^-1 aqueous solution of a weak monobasic acid HA is 20% dissociated (HA <=> H+ + A-). Take K_f=1.86 and K_b=0.52 K kg mol^-1, with Delta T=iKm. Whi... JEE Advanced level
• 1.22 g of benzoic acid (molar mass 122 g mol^-1) dissolved in 50.0 g of benzene lowers the freezing point by 0.640 K (K_f=5.12 K kg mol^-1). Benzoic acid dimeri... JEE Main level
• A carboxylic acid HA (0.50 mol kg^-1 formal molality) is dissolved in a solvent with K_f=5.0 K kg mol^-1 in which it trimerises: 3 HAleftharpoons(HA)_3 with deg... JEE Advanced level
• A 0.200 mol kg^-1 aqueous solution of CaCl2 is 80% dissociated. With K_b=0.52 K kg mol^-1 and a normal boiling point of 100 degC for water, the boiling point of... JEE Main level
• The boiling point of a 0.200 mol kg^-1 aqueous solution of a weak monobasic acid HA is elevated by 0.130 K. Take K_b=0.52 K kg mol^-1, Delta T_b=iK_bm and the e... JEE Main level
• Which statements about the van't Hoff factor i are correct? JEE Main level
• A weak electrolyte AB2 dissociates as AB2 <=> A^2+ + 2B- with degree of dissociation alpha. The van't Hoff factor is NEET level
• 3.0 g of ethanoic acid (molar mass 60 g mol^-1) is dissolved in 100 g of benzene, where it partly dimerises: 2 HA leftharpoons (HA)_2. The observed depression o... JEE Advanced level
• A 0.100 mol kg^-1 aqueous solution of a weak monobasic acid HA has K_a=1.2x10^-2. Assume molality equals molarity numerically, use the full quadratic expression... JEE Advanced level
• A solute HA (formal molality 0.20 mol kg^-1) dimerises in benzene (K_f=5.12 K kg mol^-1), and 80% of the HA is present as dimers. Which statements are correct? JEE Advanced level
• Assuming complete ionisation, the freezing point of a 0.0100 mol kg^-1 aqueous solution of K4[Fe(CN)6] is (take K_f=1.86 K kg mol^-1) JEE Main level
• Four aqueous solutions are prepared: (P) 0.100 mol kg^-1 glucose, (Q) 0.040 mol kg^-1 NaCl, (R) 0.035 mol kg^-1 Al2(SO4)3, (S) 0.045 mol kg^-1 Na3PO4. Assume th... JEE Advanced level
• 16.4 g of Ca(NO3)2 (molar mass 164 g mol^-1) is dissolved in 90 g of water (molar mass 18 g mol^-1). At the temperature of the experiment pure water has a vapou... JEE Advanced level
• An aqueous solution contains 0.10 mol kg^-1 NaCl (completely dissociated) and 0.20 mol kg^-1 glucose. Use K_f=1.86 and K_b=0.52 K kg mol^-1. Which statements ar... JEE Advanced level
• A 0.050 mol kg^-1 aqueous solution of K2SO4 freezes at -0.255 degC. Using K_f=1.86 K kg mol^-1, determine the experimental van't Hoff factor i (defined by Delta... JEE Main level
• Aqueous solutions of NaCl, urea and CaCl2 of the same molality (complete dissociation of the salts) are compared. The correct order of increasing depression of ... NEET level
• Ethanoic (acetic) acid dissolved in benzene exists as dimers through hydrogen bonding. If the acid is completely dimerised, the van't Hoff factor is NEET level