Balancing Chemical Equations

1. Balancing Chemical Equations Inquiries in Science Chemistry Series Deborah Semmler

2. Carolina Biological Supply CompanyBalancing Chemical Equation Kit Item# 251207 $109.95 Refill #251257 $84.95

3. Purpose • Study 4 types of chemical reactions • synthesis • decomposition • single replacement • double replacement • Predict the products of reactions • Write and balance chemical equations

4. Included with the kitNeeded but not supplied • 50 g copper shot • sucrose • magnesium ribbons • 1 M hydrochloric acid • 0.1 M calcium chloride • hydrogen peroxide • Silver nitrate • Sodium chloride • Sodium hydroxide • Zinc • 100 aluminum weighing dishes • manuals • bunsen burners • ring stands • rings • wire gauzes • test tubes • crucibles • tongs • scissors

5. Procedure • 1. Engage Activity: to help students reach an understanding of chemical reactions and to be able to accurately write, balance and classify chemical equations. • Comment: this engage activity does not seem to fit the bill. It doesn’t have them doing anything except developing a list of common reactions.

6. Explore • Synthesis Reaction 1. Add a few copper shot to an aluminum weighing dish. 2. Place on a ring stand with wire gauze. 3. Heat for 5 minutes noting any changes as the metal reacts with oxygen in the air. 4. Observe the final product. 5. Remove when cool. (after about three to five minutes) • Decomposition • Add enough sucrose to lightly cover the bottom of an aluminum weighing dish. • Heat the sugar on the wire gauze until the boiling ceases, noting any changes. • Observe the final product. • Remove when cool. 3-5 minutes.

7. Explore • Single Replacement • Cut a small piece of magnesium ribbon and place in the bottom of an aluminum weighing dish. • Add enough hydrochloric acid to cover the ribbon. • Note any changes in the sample. • Double Replacement • Add a small amount of sodium carbonate to a test tube. • Add a small amount of calcium chloride solution until a noticeable reaction occurs. • Observe the final product and note any changes that have occurred.

8. Explain • This is a flexible section that can be worked on together as a class, between lab partners or individually. It can also be used after the Extend activities. • Comment: I don’t think most students will be able to do this section without a lot of help if this is their first exposure to it. Not only are they to balance equations but they are also supposed to anticipate products.

9. Extend • For this section, you are to use the information you learned in the explore activities to design your own reaction. • Pick one substance from column A and the corresponding item from column B and design an experiment using the Experimental Design Template. • All experiments must be approved before you begin the experiment.

10. Comments: • I had hoped this would be more about balancing equations than determining types of reactions. • As an experiment that helps determine types of reactions, I guess it is okay, but the students will need to be familiar with these prior to these experiments. They also will need quite a bit of prior knowledge of chemical reactions and compound formation before they would be able to determine for example whether the synthesis reaction is using Cu +1 or Cu +2. • Also- the idea of letting them just combine what they want is scary. I don’t like how the directions for this section is written- sound like they can just add what they want. Later it does specify adding the corresponding item from column B, but I would have to rewrite these. • Not what I was looking for.