What’s My pH? An Acid-Base Flowchart for General Chemistry

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 15 (2010) pp 461-463

What’s My pH? An Acid-Base Flowchart for General Chemistry

Michelle M. Ivey

Harriet L. Wilkes Honors College, Florida Atlantic University; 5353 Parkside Drive, Jupiter, FL 33458, mivey@fau.edu
Received June 7, 2010. Accepted September 23, 2010.

Published: 22 December 2010

Abstract. Acid-base chemistry problems are difficult for students in General Chemistry. Most acid-base problems take the following form: Solution A and Solution B are mixed in a flask, what is the pH? Despite what appears to be a simple problem, there are five different problems that take this form, depending on the identity of A and B (strong acid, strong base, weak acid, weak base), and each type of problem is solved in a different way. Acid-base problems are also difficult because they often involve multiple steps to arrive at an answer, rather than just plugging into an equation. Here, an acid-base decision flowchart is presented to help students decide what type of problem they are being asked to solve. A review sheet is also provided so that the students can test themselves to make sure they can differentiate between each type of problem, and practice solving different types of problems.

Key Words: Laboratories and Demonstrations; general chemistry

(*) Corresponding author. (E-mail: mivey@fau.edu)

Article in PDF format (118 KB) HTML format

Supporting Materials:

A full page version of figure 1, suitable for handing out to students, and two versions of a review problem set are available online. Answer keys to both problem sets are also provided. The K_a and K_b values used in the answer key for the quantitative version of the problem set were from Whitten’s Chemistry [20]. A student handout to accompany the flowchart is also included, which contains a review of the equations used in acid-base chemistry, with more explanation than is possible in a one page flowchart. These materials were prepared with Microsoft Word (2003 SP2) (194 KB).