The Sweet Spot

Sweet Spot is an activity developed by Learning Undefeated to help students explore the process of titration and quality control in food and beverage manufacturing.

In this activity, students act as quality control managers within a sports drink manufacturer, Zest Quest, which specializes in lemon-flavored sports drinks. Lemon sports drinks use citric acid, an acid, to create the lemon flavor. It is important for the concentration (molarity M) of citric acid to be correct to ensure that it meets quality standards for safety and taste. Consuming a high concentration of citric acid can be too sour and harmful in some situations. Too little will cause the sports drink to be flavorless.

The levels of citric acid, and therefore the appropriate levels of acid needed to flavor the sports drink safely, can be determined through a process called acid/base titration. A titration is a way of determining the concentration of a substance by adding a known concentration of a reagent until a certain effect (color change) is seen. In this activity, students will perform an acid/base titration to determine the molarity of a lemon-flavored sports drink. With their findings, they will determine if the sports drink product is acceptable for sale.

Learning Objectives

Standards Alignments + Connections

Next Generation Science Standards Connections

HS-PS1-2. Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.

Virginia Science Standards of Learning Connections

CH.4B: Stoichiometry mathematically describes quantities in chemical composition and in chemical reactions

CH5.A: Molar relationships determine solution concentration

Activity Components

Activity

DOWNLOAD STUDENT HANDOUT (above)

Learning Undefeated is releasing a new citrus sport drink called Zest Quest and with your background in chemistry, you have been hired to be the Quality Control Manager. As product comes off the line, it is your team’s responsibility to ensure that it meets quality standards for safety and taste. Market research has found that most people find a very specific concentration of citric acid to be the best lemon flavor. When measuring concentration of acids we use molarity (M). Molarity measures how much of a substance, or the moles of a substance, are in one liter of solution.

The molarity of a substance can be determined through a process called acid-base titration. A titration is a way of determining the concentration of a substance by adding a known concentration of a reagent. Most titrations use visual indicators, like phenolphthalein or bromophenol blue, to signal when the titration is complete.

In our lab, we will add a known concentration of a strong base, sodium hydroxide (NaOH), to a small sample of our sports drink. We will add base slowly until we see a color change. The color change is due to a change in pH which we can observe by adding a pH indicator. When the mixture’s color has been changed from clear to pink, then it has reached its equivalence point, and the acid has been neutralized.

Post-Laboratory Extension

Have students design their own sports drink manufacturing plant. Using the concentration of citric acid found in the lab, determine the larger scale amounts needed for daily production based on the customers their manufacturer would be producing for.

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