Student understanding of pH: “i don't know what the log actually is, i only know where the button is on my calculator”

Abstract

In foundation biochemistry and biological chemistry courses, a major problem area that has been identified is students' lack of understanding of pH, acids, bases, and buffers and their inability to apply their knowledge in solving acid/base problems. The aim of this study was to explore students' conceptions of pH and their ability to solve problems associated with the behavior of biological acids to understand the source of student difficulties. The responses given by most students are characteristic of an atomistic approach in which they pay no attention to the structure of the problem and concentrate only on juggling the elements together until they get a solution. Many students reported difficulty in understanding what the question was asking and were unable to interpret a simple graph showing the pH activity profile of an enzyme. The most startling finding was the lack of basic understanding of logarithms and the inability of all except one student to perform a simple calculation on logs without a calculator. This deficiency in high school mathematical skills severely hampered their understanding of pH. This study has highlighted a widespread deficiency in basic mathematical skills among first year undergraduates and a fragmented understanding of acids and bases. Implications for the way in which the concepts of pH and buffers are taught are discussed.

From pKa to the pH of weak base solutions

“…The biochemical importance of weak acids and bases makes them prominent in introductory chemistry courses, but students often find their quantitative treatment difficult . Conjugate acid–base analysis begins with the observation that the ionic product of water, K w , is exactly equal to 1.0 × 10 −14 at 25°C .…”

Using PyMOL to Explore the Effects of pH on Noncovalent Interactions between Immunoglobulin G and Protein A: A Guided‐Inquiry Biochemistry Activity

“…Noncovalent interactions, hydrogen bonding, and pH/p K a are foundational concepts for biochemistry courses , yet research in biochemistry education has described students' difficulties with these concepts . Common misconceptions include the ideas all hydrogens are capable of hydrogen bonding , hydrogen bonds can be induced, and confusion of a hydrogen bond with a covalent bond between hydrogen and another atom .…”

“…Although noncovalent interactions and pH/p K a are foundational concepts in biochemistry they are often taught in isolation, resulting in few meaningful connections between the concepts for students. Previous research has shown that students' conceptual understanding of pH/pK a is fragmented, with students relying heavily on rote memorization of definitions of acids and bases . One particular challenge associated with this concept are the multiple models that chemists employ for acids and bases .…”

“…Even though students have had instruction regarding the concepts of acids and bases, pH and p K a in several courses by the time they begin their study of biochemistry, many students have difficulties with the concepts and applying them to biological systems . Students depend heavily on symbolic manipulation of mathematical concepts to communicate their understanding of pH and p K a . Previously published exercises on acids and bases seek to assist students with connecting the mathematics to the chemical concepts and research suggests that biochemistry curricula need to provide students with opportunities to integrate these important concepts .…”

“…Students depend heavily on symbolic manipulation of mathematical concepts to communicate their understanding of pH and p K a . Previously published exercises on acids and bases seek to assist students with connecting the mathematics to the chemical concepts and research suggests that biochemistry curricula need to provide students with opportunities to integrate these important concepts .…”