1. Balancing Chemical Equations © 2008 Gnomus @ IMSLI Nome Baker, Ph.D., Nicole Ng, and Asya Grigorieva End the slide show →

2. Find the right Answer (A Card) to Question Card (Q1). There are four Answer Cards (A1 – A4). Only one card shows a chemical reaction that is balanced. Reminder: In a chemical reaction all the atoms in the reactants appear in the products. Check each Answer Card to make sure that no atoms disappear during the reaction. Helpful hints →

3. The first Question Card (Q1) To review the related experiment you did earlier. Click here → Click here to find the card→

4. Hints that might help you find the correct Answer Cards: Start the game → Hint 1: See if the reactants named in Q1 are found in your Answer Card. Hint 2: See if these three products are formed: Carbon dioxide ( CO 2 ); Water (H 2 O); One other compound (NaHCO2).

5. Is Card A1 the correct card? Are both of the reactants that Q1 asks you to look for shown in Card A1? Is the reaction in Card A1 balanced? No? Try another Answer Card → Yes? Check your Answer →

6. No. A1 is not the right card. Card A1 does not show the correct reactants. Card A1 does not show a balanced reaction. Count and compare the total number of C, H, O and Na atoms in the reactants and in the products of the “equation” shown as a model reaction: Reactants: No. of C atoms ____; No. of H atoms ____; No. of O atoms ____; No. of Na atoms ____ Products: No. of C atoms ____; No. of H atoms ____; No. of O atoms ____; No.of Na atoms ____ Try another Answer Card →

7. Is Card A2 the correct card? Are both of the reactants that Q1 asks you to look for shown in Card A2? Is the reaction in Card A2 balanced? No? Try another Answer Card → Yes? Check your Answer →

8. No. A2 is not the right card. Card A2 does not show the correct reactants. Card A2 does not show a balanced reaction. Count and compare the total number of C, H, O and Na atoms in the reactants and in the products of the “equation” shown as a model reaction: Reactants: No. of C atoms ____; No. of H atoms ____; No. of O atoms ____; No. of Na atoms ____ Products: No. of C atoms ____; No. of H atoms ____; No. of O atoms ____; No.of Na atoms ____ Try another Answer Card →

9. Is Card A3 the correct card? Are both of the reactants that Q1 asks you to look for shown in Card A3? Is the reaction in Card A3 balanced? No? Try another Answer Card → Yes? Check your Answer →

10. Yes. You got it right! A3 is the right card. Check for yourself: Does Card A3 show the correct reactants? Does Card A3 show a balanced reaction. Count and compare the total number of C, H, O and Na atoms in the reactants and in the products of the “equation” shown as a model reaction: Reactants: No. of C atoms ____; No. of H atoms ____; No. of O atoms ____; No. of Na atoms ____ Products: No. of C atoms ____; No. of H atoms ____; No. of O atoms ____; No.of Na atoms ____ More about this activity →

11. Is Card A4 the correct card? Are both of the reactants that Q1 asks you to look for shown in Card A4? Is the reaction in Card A4 balanced? No? Try Answer Card 3 again → Yes? Check your Answer →

12. No. A4 is not the right card. Card A4 does not show the correct reactants. Card A4 does not show a balanced reaction. Count and compare the total number of C, H, O and Na atoms in the reactants and in the products of the “equation” shown as a model reaction: Reactants: No. of C atoms ____; No. of H atoms ____; No. of O atoms ____; No. of Na atoms ____ Products: No. of C atoms ____; No. of H atoms ____; No. of O atoms ____; No.of Na atoms ____ Look at Card A3 again →

13. Review of the experiment Graphic: Remember what happened when you added baking soda to vinegar??? Baking soda (NaHCO 3 ) was added to vinegar (5% acetic acid in water). The reaction between sodium bicarbonate and formic acid is very similar to the one that you did in your experiment with baking soda and vinegar. Compare the chemical structure of acetic acid with that of formic acid. Review the reaction →

14. Review of the reaction used in your earlier experiment The following will be shown when this slide is selected: The equation describing the reaction between sodium bicarbonate and acetic acid (mixing baking soda with vinegar). Compare the structures of acetic acid and formic acid →

15. Comparison of the structures of acetic acid and formic acid Structure and formula of acetic acid: [Acetic acid was used in your earlier experiments. It has similar properties to formic acid (see Card Q1).] Structure and formula of formic acid: Begin the game →

16. You have completed this example of the Gnomus unit on Balancing Chemical Equations This unit has four parts: The Q1 – Q4 series. This unit has four parts: The Q1 – Q4 series. The example shown here focuses on the Q1 series only. The rest of the “game” integrates graphic molecular models with the corresponding balanced chemical equations. Final comment →

17. About this activity This “Gnomus game” reinforces the concept that all of the atoms in the reactants appear, rearranged, in the products of the reaction. This concept had been taught, but not well learned in the classroom. In the Q2- Q4 series, not shown here, students practice relating the molecular models that describe chemical reactions to the notations used by chemists in describing them through balanced equations, emphasizing the use of coefficients and of subscripts. Students who enjoyed this activity had already been exposed to chemical reactions and equations after studying the periodic table, simple atomic structure, properties of matter, and two chemical reactions. The latter involved hands-on experimentation (an introduction to controlled experiments). One of the experiments was based on the reaction between sodium bicarbonate and acetic acid, which students may review as part of this game. End the game →