CHEM.12.E

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The student is expected to define pH and calculate the pH of a solution using the hydrogen ion concentration.
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Knowledge and Skills Statement

Science concepts. The student understands and applies various rules regarding acids and bases.

any substance that in aqueous (water) solution tastes sour, changes blue litmus paper to red, reacts with some metals to liberate hydrogen, reacts with bases to form salts, promotes chemical reactions (acid catalysis), and has a pH less than 7

any substance that in aqueous (water) solution is slippery to the touch, tastes bitter, changes the color of indicators (e.g., turns red litmus paper blue), reacts with acids to form salts, promotes certain chemical reactions (base catalysis), and has a pH greater than 7

the concentration of hydrogen ions in a solution expressed usually in moles per liter or in pH units and used as a measure of the acidity of the solution

a measure of acidity and alkalinity of a solution that is a number on a scale from 0-14 where 7 represents a neutral solution, lower numbers indicate increasing acidity, and higher numbers indicate a base; a measure of the relative amount of free hydrogen (H+) and hydroxyl (OH-) ions in the water

a substance in which a solid, liquid, or gaseous substance is evenly distributed (or dissolved) within a liquid or sometimes a gas or solid

Research

Costa, Samuel C. and Julio C. B. Fernandes. "Listening to pH." Journal of Chemistry Education 96, no. 2 (2019): 372–376. https://doi.org/10.1021/acs.jchemed.8b00641

Summary:  We developed a simple device to teach the concept of pH to visually impaired people through an experimental approach. Using an audio file that emits sound frequencies, visually impaired students were trained to associate specific frequencies with pH values. There is a direct relationship between the logarithm of sound frequency from a given musical note and a pH value, which can be used to train students with low vision who would otherwise have difficulty observing pH values from visual indications.

Research

Jayant, Lalitha. "Using Beads to Teach pH." The American Biology Teacher 71, no. 1 (2009): 12. https://doi.org/10.2307/27669356

Summary:  The inverse relationship between pH and hydrogen ion concentration is difficult for students to visualize. Most often, students cannot comprehend why pH increases when hydrogen ion concentration decreases. While they can understand the pH scale, interpreting its association with hydrogen ion concentration is confusing. I play a simple game with my students to help them grasp this concept. We then do a real experiment to confirm it.