Module 5 Intro
1. Module 5 Intro
1.4. Page 2
Module 5—Acids and Bases
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Try This
An Acid-Base Reaction
What do you understand about acids and bases? In previous science courses you may have investigated their properties, but how do they behave when they are combined? In this activity you will examine the reaction of baking soda (sodium hydrogen carbonate) with vinegar (an aqueous solution of ethanoic acid). Follow these steps:
Step 1: Write the chemical formulas, including their states, for solid sodium hydrogen carbonate and aqueous ethanoic acid.
Step 2: Place 50 mL of vinegar into a 100-mL beaker or drinking glass.
Step 3: Add 5 mL (1 teaspoon) of baking soda to the beaker containing the vinegar.
Step 4: Observe any changes that occur.
TR 1. A group of Chemistry 20 students suggests that the balanced chemical equation for the reaction between baking soda and vinegar is
NaHCO3(s) + CH3COOH(aq) → NaCH3COO(aq) + CO2(g) + H2O(l)
Use your observations to support or argue against the suggested equation. Identify any additional tests you might want to perform to support your answer.
Try This Answer
TR 1. The proposed chemical equation is correct. A gas is produced, as indicated by the equation, along with neutral products. This is consistent with the definition for an acid-base reaction.
Further tests may include a litmus test—to determine whether the products are acidic, basic, or neutral—and a limewater test—to identify whether the gas produced is carbon dioxide (limewater turns cloudy = carbon dioxide present).
Discuss
The reaction you observed in the Try This activity above is identical to the reaction you used to simulate the eruption of a volcano when you completed Module 1, Lesson 5. Chemical reactions often form the basis of many science projects and toys.
Use the Internet, or other sources of information, to find a project or toy that requires the reaction between baking soda and vinegar.
Prepare a brief summary of the project or activity that explains why this chemical reaction is involved. Include a list of the sources you used to prepare your summary.
Post your summary to the class discussion area. Read the summaries from a minimum of three other students and identify similarities and differences in the way the reaction is used.
Retrieve the copy of Module 5: Lesson 1 Assignment that you saved previously to your course folder. Copy and paste your posting to the appropriate section in the assignment. Complete other parts of the table. After you have completed Part 1 of the assignment, save your work to your course folder. You will receive information about how to complete the other part of the assignment later in this lesson.