Unit 1: Solutions

Unit Overview

So far in chemistry our focus has been on pure substances, but most of what you see around you is a complicated mixture of stuff. Solutions, homogenous mixtures of two or more substances, are the next step in complexity after pure substances. The properties of a solution depend not only on the physical properties of the individual substances in the mixture, but also on the relative amounts of those constituents.

A note on the Practice problems: The more of the exercises you do, the better you will do on the exams. The problems I have suggested for practice are an absolute minimum, and proficiency with these problems should indicate at least a C level understanding of the material.

11.1 The Dissolution Process

• • Describe the basic properties of solutions and how they form

  • Predict whether a given mixture will yield a solution based on molecular properties of its components

  • Explain why some solutions either produce or absorb heat when they form

Review: section 10.1, "Intermolecular Forces" in the text.

Read: Chapter 11, section 11.1

Watch:

Intro to solutions, 11.1

Concentration units

Concentration units 11.4a

Practice:

Exercises ch 11: 3,5,6,7,8

11.2 Electrolytes

• • Define and give examples of electrolytes

  • Distinguish between the physical and chemical changes that accompany dissolution of ionic and covalent electrolytes

  • Relate electrolyte strength to solute-solvent attractive forces

Read: Chapter 11, section 11.2

Watch:

Electrolytes 11.2

Practice:

Exercises ch 11: 9,11,14,15

11.3 Solubility

• • Describe the effects of temperature and pressure on solubility

  • State Henry’s law and use it in calculations involving the solubility of a gas in a liquid

  • Explain the degrees of solubility possible for liquid-liquid solution

See my page on Errata for comments about example 11.2 in the OS text.

Read: Chapter 11, section 11.3

Watch:

Practice:

Exercises ch 11: 17,18,20,23

11.4 Colligative Properties

• • Express concentrations of solution components using mole fraction and molality

  • Describe the effect of solute concentration on various solution properties (vapor pressure, boiling point, freezing point, and osmotic pressure)

  • Perform calculations using the mathematical equations that describe these various colligative effects

  • Describe the process of distillation and its practical applications

  • Explain the process of osmosis and describe how it is applied industrially and in nature

Review: concentration units

Read: Chapter 11, section 11.4

Watch:

11.4a Concentration units (if you didn't watch it above)

11.4b Colligative properties

Practice:

Exercises ch 11: 33,35,39,41,45,49,51,59 (and any others you have time for)

note: the 11.4b video was recorded for the spring 2020 CHY 115 offering. Two things I note on watching it: first, there were several points in the video where it sounded to me like I was saying "molar" when I meant "molal" and vice versa. Pay attention to what's written on the screen :) m=molal, M=molar. Second, the video mentions a Monday meeting to do problems. We'll be doing something like that with the LAs but it won't necessarily be Monday.

11.5 Colloids

Want to know more about whipped cream? Cleaning up oil spills? Read this section. It won't be on the exam.