Question

COLLIGATIVE PROPERTIES- HOMEWORK 1 Calculate the bp o ate the bp of a solution made by dissolving 20.0g of quinone (CH.03) acetone (bp of acetone- 56 5C, k, = 1 67'Cimolal). 2A sample of comp of compound X weighing 1 2869 was dissolved in 259 benzone K5 12S pe 5.50°C) and the fo of the resulting solution was found to be 3.27 Suiting solution was found to be 3 27°C What is the MW of X7 og of a compound (MW-92) are dissolved in 100g of water, what if the bp of the so Given K 0.512"C/molal 4. When 40.09 when 40. Og of a compound Y are dissolved in 500g benzene (K-2.53°C molat bpou the resulting solution has a bpe 81.4°C. What is the MW of Y? 8.0°C/molat, fpe 70.00) . When 0 650g of compound Wis dissolved in 27.8g biphenyl (K fp of the solution is 68.44'C. What is the MW of W? 6. A compound has the following composition: C=93.75% and H=6.25%. When 0.320g of the compound is dissolved in 10 og benzene ( K 5.12"C/molal, fpe 5.50°C) the solution has a lot 4 20'C. Calculate a) the empirical formula and b) the molecular formula

Answer 1

1.

Molar mass of quinone

C6H402 = 6(12) + 4(1) +2(16) = 72 +4+32 = 108 g/mol

Molality of quinone

20.0 g x 1000 g/kg 108 g/mol x 100.0 g = 1.85 m

The elevation in the boiling point

47 = K xm

AT, = 1.67 C/m x 1.85 m

AT) = 3.09

The boiling point of acetone is .

56,5 g

The boiling point of solution

To = 56.5 °C +3.09

To = 59.6 °C