Solutions

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This is a 10 point assignment

Objectives: After completing this unit, students should be able to:

1. Explain the solution process (solvation).
2. Describe the energy changes that occur during solvation and relate these to particle interactions.
3. Use the phrase “like dissolves like” to predict whether two substances will be soluble in each other.
4. Define the terms solubility, miscible and immiscible.
5. Given the solubility of gas in a liquid at one pressure, determine the solubility at a different pressure using Henry’s Law.
6. Explain the effect of temperature and pressure on solubility.
7. Solve problems involving mass percent, parts per million (ppm), parts per billion (ppb), mole fraction, molarity and molality.
8. Describe the colligative effects of solute particles on the vapor pressure, boiling point, freezing point and osmotic pressure of a solution.
9. Use Raoult’s Law to calculate a solution’s vapor pressure.
10. Calculate the boiling point and freezing point of solutions from colligative properties data.
11. Calculate molar masses and molalities from colligative properties data.
12. Define osmotic pressure and calculate osmotic pressure, molarity or the van’t Hoff factor given information about the solution.

Reading and Homework Exercises

Table of Contents from: OpenStax Chemistry 2e: Chapter 11 – Sections 1-4, Chapter 3 sections 3.3 and 3.4

Objective 1-4 Practice – Questions 1-13 address various concepts in solubility and the application of the “like dissolves like” rule.

You might find the following reading in OpenStax helpful:

Introduction

11.1 The Dissolution Process

For a mixture of ethanol (C₂H₅OH) and water, answer the following questions:

Question 1:

Question 2:

Question 3:

Question 4:

Question 5:

For a mixture of butane (C₄H₁₀) and hextane (C₆H₁₄), answer the following questions:

Question 6:

Question 7:

Question 8:

Question 9:

Question 10:

For a mixture of butane (C₄H₁₀)  and water, answer the following questions:

Question 11:

Question 12:

Question 13:

11.2 Electrolytes

Review this section as needed.  It was studied in Unit 2.

Objective 3, 5 and 6 Practice – Questions 14-18 address effects of temperature and pressure on solubility and give additional practice  on  the application of the “like dissolves like” rule.

You might find the following reading in OpenStax helpful:

11.3 Solubility

Question 14:

Question 15:

Question 16:

Question 17:

Question 18:

Objective 7 Practice – Questions 19-26 practice calculations using the various ways solution concentration is measured.

Concentration of solutions

Review: section 3.3 (Molarity)

Read section 3.4 (mass percentage, parts per million, and parts per billion only), section 11.4 (first part – mole fraction and molality only)

3.3 Molarity – review as needed

3.4 Other Units for Solution Concentrations – mass %, PPM and PPB only

11.4 Colligative Properties – mole fraction and molality

A solution is prepared by adding 3.62 g of glucose, C₆H₁₂O₆ , to 100.0 g of water. The final volume of the solution was 104.0 mL. Answer the 2 following questions for the solution:

Question 19:

Question 20:

Question 21:

Answer the following concentration questions:

Question 22:

Question 23:

Question 24:

Question 25:

Question 26:

Objective 8-12 Practice – Questions 27-26 address various colligative property concepts and calculations

Colligative Properties

Review: section 3.3 (Molarity)

Read section 3.4 (Vapor Pressure Lowering subsection through end of section)

11.4 Colligative Properties – Begin at Vapor Pressure Lowering 

In the next question, calculate the vapor pressure of each of the two aqueous solutions at 25°C.  The vapor pressure of pure water at 25°C is 23.7 torr.

Question 27:

Question 28:

Question 29:

Question 30:

In the next question, calculate the boiling point and freezing point temperatures of each of the two aqueous solutions at 25°C.  Use the appropriate boiling point elevation and freezing point depression constants in Table 11.2

Question 31:

Question 32:

Question 33:

Question 34:

Question 35:

Question 36: