Chemical Reactions

Reactants and Products

Write down Exothermic and Endothermic definitions

Vocabulary Assignment

Label the following Chemical Reaction with the four vocabulary terms for this lesson. Each term corresponds to some part of this equation.

Looking at a Chemical Reaction on Paper

A chemical reaction is the result of combining different substances together to create a new substance. Often, a catalyst is needed to help the reaction move faster, but it is not a necessary part of ALL reactions . When the reaction is written down it is called a Chemical Equation.

Here is an example:Hydrogen combines with Oxygen to produce Water

(the arrow is like an equal sign)

The Chemical Equation is the entire line, the Product is water and the Reactants are the hydrogen and oxygen.

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The Same Elements are found on BOTH Sides

If you look at the equation from the previous page, is there anything DIFFERENT produced in the end?

NO.We START with Hydrogen and Oxygen and END with Hydrogen

and Oxygen. We don’t have nitrogen or carbon in the final product, we just have a changed substance (or substances) made up of the original elements.

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Before and After

There is a great article to help illustrate Chemical Equations a

little more in depth. Go to“Before and After” in the

8th Grade Cyber Text. Read through the information

presented on that page.Please note that the video links are

not working. Use the following links instead:

Space Shuttle LaunchCalcium Metal and Water

Chemical Reactions Around Us

In the Vocabulary Assignment, the example we used was the equation for Photosynthesis. It is a very common reaction that takes place all around us. We learned more about this vital process in Lesson 2. We have also learned about SEVERAL other common reactions that occur in the lessons that we have completed up to this point.

Your assignment is to identify three other common SIGNIFICANT chemical reactions (they could include reactions we have learned about, just not photosynthesis). Write these down on a paper, identify what the reactants and products are in these chemical reactions. Also include any catalysts that might play a part in these reactions. Explain why each is considered SIGNIFICANT.

Law of Conservation of Mass

Think of the chemical reactions we have used as examples so far. We know that the same elements that go into a reaction will come out, also. However, what can you say about the numbers involved in these equations?

Just as the actual elements remain the same, so do the amounts of the elements that go into a reaction, and the amounts that comes out.

This is the Law of the Conservation of Mass. Whatever mass is present at the beginning of a chemical reaction will be present at the end.

Balancing Chemical Equations

To better understand the Law of Conservation of Mass, we should learn how to Balance Chemical Equations. Then you can “SEE” how the Mass from the beginning is still present at the end, even when it seems as though something new was created.

Click on Balancing Chemical Equations to go to a page that will explain, in detail, how to do this the right way. At the end there are 10 equations for you to do, these are practice, and the answers are available to you. Work through these 10, checking your answers as you go. Make sure you understand this, if not, review the page and then try the equations again. If it seems difficult, you might need to use physical objects (like coins) to represent the elements in the equations. Sometimes we just need to get our hands on a problem in order to come up with the solution.

Turning Green with Envy

Pennies have become so envious of the other coins being worth more that they are beginning to turn GREEN. To check this out, we are going to conduct an experiment to see what makes pennies turn green, and what makes it happen faster.

Green Pennies: Purpose

Perhaps you have seen green pennies before. It is a fairly common reaction that takes place between the copper and the oxygen in the atmosphere. The Statue of Liberty has had this reaction take place, which explains her familiar green hue. The purpose of this lab is to find out that different substances can cause the reaction to happen at different rates.

Green Pennies: Assignment

Use the Scientific Method to write up this investigation of Green Pennies. Begin with your problem (or question). Now review over the materials and procedure (on the next page) and form your hypothesis. Test the hypothesis, analyze your data and from a conclusion. Be sure to include a graph that visually shows the data you collected from the experiment

Green Pennies: Materials/Procedure

Materials:• Pennies• Paper Towels• Saucers• Vinegar• Salt Water (mix your

own*)• Coke or Pepsi• Any other substance of

your choice

Procedure:Fold the paper towels a few times to get a

thicker towel. Set it in a saucer.Pour a substance over the towel until it is

saturated.Put four pennies on the towel and then let it set.Repeat with the other substances, you should

have four.Let it sit for 1 day and see what happens. Make

occasional observations over that 24 hour period.

* Salt water can be made by mixing 10 Tablespoons of water with 3 Tablespoons of salt. Mix until the salt is completely dissolved.

Applying Principles of Chemistry

Technology has increased dramatically over the past century, we have countless new inventions that bring more ease, safety and speed into our lives.

Based on what you have learned about Chemical Reactions throughout this unit, it is your turn to think about how Scientists and Engineers have applied principles of chemistry to any aspect of our everyday lives?

Write a one page report about some invention or technique that has come about in the last 100 years that causes a chemical reaction to begin, or to be prevented from occurring, which, in turn, brings ease, safety and speed into our daily life.