Part 1: Engage (Anchoring Phenomenon)

Phenomenon: When you mix baking soda and vinegar, it violently fizzes and creates bubbles. However, if you mix salt and water, the salt simply disappears into the liquid without any fizzing, heat, or obvious change. Chemists can look at the chemical formulas of two substances and accurately predict exactly what will happen when they are mixed, even before doing the experiment.

Questions:

  1. Why do some chemicals react dramatically when mixed, while others seem to do nothing at all?
  2. What information do you think a chemist needs to know about the atoms in order to predict if a reaction will occur?
  3. If atoms are never created or destroyed, where do the new substances (like the bubbles) come from during a chemical reaction?

Part 2: Explore (Simulation Investigation)

Access the simulation: Chemical Reaction Outcomes Predictor

Investigation Instructions:

  1. Open the simulation and select the Synthesis reaction type from the menu.
  2. Choose Sodium (Na) and Chlorine (Cl₂) as your reactants. Run the simulation.
  3. Observe the products. What new compound is formed? Record the balanced chemical equation shown in the simulation.
  4. Now, select a Single Replacement reaction. Choose Zinc (Zn) and Hydrochloric Acid (HCl). Run the simulation.
  5. What are the products of this reaction? Which atom was “replaced”? Record the balanced chemical equation.
  6. Try predicting the outcome of a Double Replacement reaction. Select Silver Nitrate (AgNO₃) and Sodium Chloride (NaCl). Before running it, guess what the products will be. Run the simulation to check your prediction. Record the final balanced equation.

Part 3: Explain (Sensemaking)

Using your data and observations from the simulation, answer the following questions:

  1. Conservation of Mass: Look at the balanced equations you recorded for the Synthesis and Single Replacement reactions. Count the number of each type of atom on the reactant side (left) and the product side (right). What do you notice? How does this demonstrate the Law of Conservation of Mass?
  2. Patterns of Reactions: In the Double Replacement reaction (AgNO₃ + NaCl), describe the pattern of how the atoms rearranged themselves to form the products. Why do the positive and negative parts of the molecules swap partners?
  3. Predicting Outcomes: Based on your observations, what general rule or pattern can you use to predict the products of a single replacement reaction compared to a double replacement reaction?

Part 4: Elaborate/Evaluate (Argumentation & Modeling)

Task: Construct an evidence-based explanation for how scientists can predict the outcome of a chemical reaction based on the properties of the reactants.