Group Activity: Two-Factor Cross



Reactants and Products Virtual LabIs mass conserved during a chemical reaction?Background Chemical reactions are processes that change chemical substances into other chemical substances. One of the key questions about chemical reactions is whether or not mass is conserved during the course of a reaction. In other words, will the mass of the product of a chemical reaction be equal to the mass of the reactants, or is mass destroyed or lost in the course of a reaction?Setup Open the activity called “Reactants and Products Virtual Lab” in your digital course. HYPERLINK "" \t "_blank" : You will have opportunities to save data at different stages of this activity. You can download data for offline purposes, such as answering questions in the Analyze and Interpret Data section of this worksheet. When you save data as an image, give it a title that matches the given experiment or the specific part of the virtual lab activity. Procedure Follow the onscreen instructions and record information below as you run through the experiments. You will be able to go back to previous parts or “reload” a part by clicking the buttons to the right of the Investigation tab. Likewise, if you go backward you can click the forward button to return to a later part.Part 1□ 1. When you mixed the potassium iodide and lead nitrate in the jar, was there any evidence of a chemical reaction? □ 2. Save an image of the data table from the potassium iodide and lead nitrate reaction and paste it below, or draw the table.□ 3. How does the sum of the masses of the reactants compare to the mass of the products? What does this indicate about the conservation of mass?□ 4. Write the balanced chemical reaction between potassium iodide and lead nitrate.Part 2□ 5. Save a copy of the data table from the baking-soda-and-vinegar reaction and paste it below, or draw the table.□ 6. Was mass conserved in this reaction? Explain.□ 7. Write the balanced chemical reaction between baking soda and vinegar.Part 3□ 8. Save a copy of the data table from the baking-soda-and-vinegar reaction that featured the use of the balloon and paste it below, or draw the table.□ 9. When you repeated the reaction and used the balloon to “close” the system, what did you notice about the mass of the reactants and the mass of the final products? Was mass conserved? Explain. Analyze and Interpret Data1.Plan Your Investigation Using real lab equipment, how could you attempt the cesium-and-water reaction depicted in this virtual lab to study whether mass is conserved in that reaction?2. Connect to Society Where do you think the law of conservation of mass is used in the real world, and why is it useful?TE SupportFocus on NGSS This lab builds toward mastery of MS-PS1-5. Students will apply the following practices, ideas, and concepts in this activity. Science and Engineering Practices Collect data about the performance of a proposed object, tool, process, or system under a range of conditions.Connect to the Core Idea Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants. Crosscutting Concept Macroscopic patterns are related to the nature of microscopic and atomic-level structures.Purpose Students will be able to explain the law of conservation of mass and how it applies to chemical reactions.Class Time 45 minutesExpected Outcome Students will master the following concepts:1. Mass is conserved in chemical reactions. 2. Conservation of mass is not always easy to detect, especially if the system is open or the reaction isn’t controllable. TE Annotations: Procedure1. Yes, there was evidence that a chemical reaction occurred. The color of the mixed reactants changed from white to yellow. A color change indicates a chemical reaction.2. Saved data table:3. The sum of the masses of the reactants is equal to the mass of the product, indicating that mass was conserved.4. 2KI(s) + Pb(NO3)2(s) -> 2KNO3(s) + PbI2(s) Note: Some students may not denote the solid states of the reactants and products. 5. Saved data table:6. Students may answer that mass was not conserved, because 17.3 grams is less than the sum of the reactants. Others may correctly infer that the carbon dioxide produced by the reaction was lost from the tube and therefore its mass was not measured.7. NaHCO3(s) + CH3COOH(aq) -> CH3COONa(aq) + CO2(g) Note: Some students may not denote the states of the reactants or products. 8. Saved data table:9. Yes, mass was conserved. The mass of the products equaled the mass of the reactants. The balloon trapped the carbon dioxide gas that had escaped earlier in the open version of the experiment.TE Annotations: Analyze and Interpret Data1. You could set up the reaction in a sealed, extremely sturdy reaction vessel from which mass could not escape. In that case I would need only to record the mass before and after the reaction. 2. Answers should mention fields or industries in which the appropriate masses or volumes of chemical reactants must be carefully brought together to produce products of certain composition and mass and/or volume. ................
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