ination February 19, 2018 SHOW ALL WORK!!! 2. 4. +8 Total 3 1. What is the freez

Question

ination February 19, 2018 SHOW ALL WORK!!! 2. 4. +8 Total 3 1. What is the freezing point of a solution containing 4.134-g of naphthalene (molar mass 128.2) dissolved into 30.0-g of paradichlorobenzene? The freezing point of pure paradichlorobenzene is 53.0°C and the freezing point depression constant, ko is 7.10 (10 Points) Answer A concentrated solution of sulfuric acid contains 65.0% H2SO4 by mass and has a density of 1.55- g/mL at 20°C. Calculate the molarity and molality of the solution. How many militers of the concentrated H,SO, are needed in order to make 250.mL of a 4.25M solution of the acid? (15 Points) 2. mL Answer: Rank O2, Ne and NH3 in increasing solubility in water. Discuss the intermolecular forces which affect the solubility. (10 Points) Least soluble: 3. Most soluble

Explanation / Answer

Ans 1

Freezing point of solution Ts =?

Moles of naphthalene = mass/molecular weight

= 4.134/128.2

= 0.0322 mol

Freezing point of pure paradichlorobenzene Tf = 53°C

Van't Hoff factor i = 1

Freezing point depression constant Kf = 7.10

Molality = moles of solute /mass of solvent

= 0.0322 mol/0.030 kg

= 1.0748 m

Tf - Ts = i x Kf x m

53 - Ts = 1 x 7.10 x 1.0748

Ts = 45.368°C

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