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Lesson 10- Reactants & Products
Vocabulary
products, reactants

You have discovered that in every chemical change, new substances are formed. These new substances are called products of the chemical change. In lesson two, when you add vinegar to baking soda to get the egg out of the bottle, carbon dioxide gas was released. Carbon dioxide is a product of this chemical change. From observing the change, you would not realize that water and sodium acetate were also formed. These are products of this chemical change as well.

The starting substances are called the reactants of the chemical change. Baking soda and vinegar are the reactants.

A word equation shows both the reactants and the products of a chemical change:

Reactants -> Products

In the activity below, you will practice writing word equations for various chemical reactions.

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Work through the word equations sheet pdf by identifying reactants and products.

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Observe the following lab. Remember to use the proper safety procedures and lab format while completing the lab.

Elephant Toothpaste button

LAB 10: WHAT DO ELEPHANTS BRUSH THEIR TEETH WITH? ELEPHANT TOOTHPASTE!
 (Write out the lab).

PROBLEM: What do you think will occur when soap is added to the hydrogen peroxide and the sodium iodide is added to the solution?

HYPOTHESIS: How do you think it is going to turn out? Use the facts you already know to come up with a guess that might really make sense.

MATERIALS:

  • 50 mL to 100 mL 30% hydrogen peroxide
  • 10 mL saturated potassium iodide solution
  • 10 mL liquid soap or dishwashing liquid
  • food coloring
  • 2 plastic garbage bags (large size)
  • a graduated cylinder (500 mL or larger, glass is preferable to plastic)
  • a pair of scissors
  • a pair of safety goggles
  • a pair of rubber gloves

PROCEDURE:

  1. Put on the safety goggles and gloves.
  2. Use the scissors to cut one of the garbage bags down one side and across the bottom. Open the bag and spread it over the demonstration area. Save the remaining bag for cleanup.
  3. Place the graduated cylinder on the open bag.
  4. Fill the cylinder to about ¼ full with 30% hydrogen peroxide.
  5. Add from 5 mL to 10 mL liquid soap or dishwashing liquid.
  6. Sprinkle some food coloring on the inside wall of the cylinder.
  7. Add 10 mL saturated potassium iodide solution.
  8. STAND BACK! In a few seconds a column of foam will rise out of the cylinder and overflow onto the open bag.

ANALYSIS:

  1. Describe what you observed.
  2. Did your observations match you predictions? How are they similar? different?

CONCLUSION: What actually occurred during this experiment?

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Do research on a chemical change. In your research, try to determine the reactants and products of that change. Include in your write-up other interesting information you may find. You will share your research with your classmates to see whether they can write a word equation for your chemical change.

Here are some possibilities:

  • What is the chemical change involved in obtaining iron from iron ore? Do an internet search for steel mill mines and see if you can find information to help you with this question.
  • Plaster of Paris is made from gypsum. What chemical change is involved?
  • What can you learn about the reactants and products in making cement?
  • Your flashlight dry cell uses a chemical change to produce electricity. What are some reactants and products in this change?
  • Talk to a photographer to learn about the chemical changes involved in taking and developing photographs.
  • The formation of limestone (calcium carbonate) caves. What is the chemical reaction that causes the caves to form?
  • Identify the chemical reaction that occurs in photosynthesis.

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Remember to use the proper safety procedures and lab format while completing the lab.

LAB 11: HOT OR COLD?
 (Write out the lab).

PROBLEM: How does temperature affect reaction rate?

HYPOTHESIS: How do you think it is going to turn out? Use the facts you already know to come up with a guess that might really make sense.

MATERIALS:

  • 4 Al ka-Seltzer tablets
  • 4 large glasses or beakers (250 mL each or larger)
  • ice
  • hot water (from a kettle)
  • thermometer
  • watch or timer

PROCEDURE:

  1. Prepare a table where you can record your results for each of the four beakers. The two columns should be labeled "Temperature" and "Time."
  2. Fill one glass with ice and water, and the others with cool, hot and very hot water.
  3. Use the thermometer and record the temperature of the water in each of the four glasses.
  4. Before the water has a chance to cool, drop one tablet into each of the four glasses at the same time. Record the time taken to complete the reaction in each glass.

ANALYSIS:

  1. What happened to the Al ka-Seltzer tablets in water?
  2. What evidence do you have that a chemical reaction occurred?
  3. How did temperature affect the rate of the reaction?
  4. Make a graph of time vs. temperature. Plot your four points on the graph and join them with a smooth curve. (Excel could be used to create this graph). Make sure you title your graph.
  5. Use the graph you created to predict the amount of time that would be necessary for a similar reaction at 40 degrees C and at 60 degrees C.
  6. Think about the following theory, "Particles in matter are constantly moving and they move more quickly at higher temperatures." Use this theory to explain your results.

CONCLUSION: What actually occurred during this experiment?

assessment/evaluation button
Lab Report Evaluation Form pdf

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