Acids and Bases

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In this unit, we continue our dive into one of the most heavily tested topics on the AP Chemistry exam, chemical equilibrium. Topics from chapters 14, 15, and 16 can comprise anywhere from 18-24% of the multiple-choice questions and an equal or greater significance on the free-response section. This is the section that helps students boost their 3s into 4s and 5s!

Introduction

So far in this course, we have defined acids and bases as chemical species that can give away H+ or OH- ions. However, this definition is limited to a very small number of molecules and ionic compounds. We will start by exploring a wide range of molecules that can affect the pH of a solution and searching for common structural features that could be causing the pH to change.

The simulation below can help with some of the visuals included in many AP problems. I recommend students play around with the simulation for a bit before the first lecture.

Identifying Acids and Bases

In this first lesson we will learn how to recognize the difference between an acid and a base simply by identifying functional groups on molecular models. Students will practice with the following vocabulary: Brønsted-Lowry acid/base, conjugate acid, conjugate base, amphoteric. Big review topics include Lewis dot structures and Arrhenius definitions of acids and bases.

Student Handouts:

Sorting Acids and Bases

Notes:

Intro to Acids and Bases, Filled Out

Worksheet:

Identifying Acids and Bases, Answers

Ranking the Strengths of Acids

In this next sequence of lessons, we will pull from our knowledge from our periodic trends and covalent bonding units to predict the relative strengths of acids based on bond strength and nearby electronegative atoms. These predictions are backed by experimentally determined acid-dissociation constants, which will lead us to our calculations in the next lesson.

Student Handouts:

Notes:

Strengths of Acids_Hydrohalic Acids-Filled Out

Worksheets:

Weak Acid pH Calculations 1, Answers (need new key)