Question

QUESTION 1 What is the strongest form of intermolecular force between solute and solvent in a solution of CH3OH(l) in H2O(l)?

1. ion-dipole 2. dipole-induced dipole 3. hydrogen bonding 4. dispersion 5. dipole-dipole

QUESTION 2 Which of the following is more soluble in water, ethanol or CBr3H(l). Don't try to type the subscripts, just use letters and numbers.

QUESTION 3 A flask containing solid ammonium chloride becomes colder as water is added and the salt dissolves. Is the magnitude of the lattice energy of NH4Cl larger or smaller than the combined hydration energy of the ions?

QUESTION 4 Which of the following sets of changes would definitely result an originally saturated solution of O2(g) in H2O(l) becoming unsaturated WITHOUT removing oxygen?

1. decrease pressure, increase temperature 2. increase pressure, decrease temperature 3. increase pressure, increase temperature 4. decrease pressure, decrease temperature

QUESTION 5 Determine the mass in grams of pentane that must be added to 28 g of benzene to make a 0.87 m solution. Give your answer to 2 decimal places.

QUESTION 6 A 3.61 mass % aqueous solution of nitric acid (HNO3) has a density of 1.12 g/mL. Calculate the molarity of the solution. Give your answer to 2 decimal places.

QUESTION 7 How many moles of solute particles are present in 6.18 mL of 0.473 M Na2SO4?

QUESTION 8 Consider the solutions, 0.04 m urea [(NH2)2C=O)], 0.04 m AgNO3 and 0.04 m CaCl2. Which has (i) the lowest osmotic pressure, (ii) the highest vapor pressure, (iii) the highest boiling point?

1. all will be the same 2. (a) 0.04 m urea (b) 0.04 m urea (c) 0.04 m CaCl2 3. (a) 0.04 m CaCl2 (b) 0.04 m urea (c) 0.04 m urea 4. (a) 0.04 m urea (b) 0.04 m CaCl2 (c) 0.04 m CaCl2 5. (a) 0.04 m CaCl2 (b) 0.04 m CaCl2 (c) 0.04 m CaCl2

QUESTION 9 Calculate the boiling point (in degrees C) of a solution made by dissolving 7.89 g of naphthalene {C10H8} in 95.9 g of cyclohexane. The Kbp of the solvent is 2.79 K/m and the normal boiling point is 80.7 degrees C. Enter your answer to 2 decimal places.

QUESTION 10 Calculate the boiling point (in degrees C) of a solution made by dissolving 3.69 g of naphthalene {C10H8} in 84.7 g of CCl4. The Kbp of the solvent is 4.95 K/m and the normal boiling point is 76.5 degrees C. Enter your answer to 2 decimal places.

QUESTION 11 When 1.28 g of an unknown non-electrolyte is dissolved in 50.0 g of carbon tetrachloride, the freezing point decreased to -27.5 degrees C from -23 degrees C. If the Kfp of the solvent is 29.8 K/m, calculate the molar mass of the unknown solute. 169.5

QUESTION 12 When 14.2 g of an unknown, non-volatile, non-electrolyte, X was dissolved in 100. g of ethanol, the vapor pressure of the solvent decreased from 58.9 torr to 56.2 torr at 298 K. Calculate the molar mass of the solute, X.

Answer 1

ANSWER.QUESTION 1. 3.Hydrogen bonding.   QUESTION 2.Ethanol. QUESTION 3.Smaller   QUESTION 4. 2.2. increase pressure, decrease temperature QUESTION 5.given that molality=0.87,weight of solvent=28 gms ,m=(w/GMW)x1000/weight of benzene weight of pentane=( 0.87x72x28)/1000=1.75 gms.   QUESTION 6.given that 3.61 mass% means 3.61 grams dissolved in 100 ml solution. Molarity=(weight of HNO3/GMW)x1000/volme of solution =(3.61/63)x1000/100=0.57 M.   QUESTION 7 .2.92x10^-3 moles of solute particles.   QUESTION 8.4.(a)0.04m urea (b)0.04m CaCl2 (c) 0.04m CaCl2.   QUESTION 9.The elevation of B.p=1.79⁰c so final temperature=82.49⁰c   QUESTION 10.The elevation of B.p=1.68⁰c so final temperature=78.18⁰c.   QUESTION 11.The molar mass M=(k_bxax1000)/T_bxb=(29.8x1.28x1000)/50x4.5 M=38144.00/=169.53.   QUESTION 12. The molar mass M=(axwxP₀ )/bx(P₀--P)=(14.2X46X58.9) /50X2.7 M=38473.48/135.00=284.99.