Question

Choose the best answer:

1. Which of the following aqueous solutions should have the lowest boiling point?

a. 0.030 m CO(NH2)2

b. 0.020 m NH4NO3

c. 0.030 M CaSO4

d. 0.035 m MgCl2

e. 0.040 m C2H6O

Answer 1

Colligative properties depend only on the concentration of solute particle. General meaning of colligative properties is "counting”, thus the colligative properties of solution depends on the number of solute particles. There are four important colligative properties which are following: 1. Vapor pressure depression. 2. Boiling point elevation. 3. Freezing point depression. 4. Osmotic pressure. All the above colligative properties follow the general relationship: colligavtive property =ix concentration (solute) constant Here the constant is a characteristic of the particular property and solvent. a. 0.030 m CO(NH2)2 is not an ionic compound thus the total number of ions in the solution is 0.030 m b. 0.020 m NH4NO3 will ionize into NH4+ and NO3- in the solution thus there are 0.040 m ions present. c. 0.030 M CaSO4 will ionize into Ca2+and so4^2- in the solution thus there are 0.060 m ions present. d. 0.035 m MgCl2 will ionize into Mg2+and 2 CI^- in the solution thus there are 0.105 m ions present. e. 0.040 m C2H60 is not an ionic compound thus the total number of ions in the solution is 0.040 m Boiling point elevation is proportional to the number of ions as follows: colligav tive property = ix concentration (solute) constant 0.035 m MgCl2 show highest boiling point