So What is a Chemical Reaction Anyway?

Posted on Feb 11 2014 in Hearts and Hands by admin

With Valentine’s Day rapidly approaching, it makes sense that our thoughts turn to sweets and treats and good things to eat. However, in order to make sure you don’t ruin your appetite, this time we are going to have some fun with things that aren’t sweet–baking soda and vinegar!

 

I did this experiment first with Princess’s Girl Scout troop and Bug, then again with SixHands. I have to say, this is a great experiment for students of any age. Plus, once you do the basic, baking-soda-and-vinegar experiment, there are so many ways to build on it to demonstrate other concepts.

Materials:

  • A flat bottomed dish or pan
  • Baking soda
  • Vinegar
  • Food coloring
  • Eye dropper or straw

Instructions:

NOTE: This first part requires a bit of clandestine preparation on your part.

 

1. In the bottom of an empty, flat-bottomed dish, drop several drops of food coloring.

2. Cover the bottom of the pan with baking soda, making sure not to disturb the food coloring. Use enough baking soda to cover the colors.

 

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3. Using an eyedropper or straw, have your child start adding vinegar to the pan of baking soda.

NOTE: To use the straw, dip it in the vinegar and place your finger over the open end. Remove the straw from the vinegar, hold it over the pan, and release your finger. You can add to the experiment by explaining to your kids that this creates a vacuum and holds the liquid inside the straw.

4. Students should continue to add vinegar to the pan until they find all the colors.

 

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After a while, SixHands got tired of the eyedropper, so he started pouring the vinegar from the glass.

 

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How and Why

This experiment was a lot of fun! When doing it with Princess’s Girl Scout troop, the girls did not know there was food coloring beneath the baking soda, so when the colors began to appear they were more than a little excited. When I did the experiment at home with SixHands, he knew that I had hidden food coloring in the pan, but he didn’t know where, so he had to hunt for it. Even at age 13, he still thought the reaction was pretty neat.

 

The cool part of this experiment is that, while it is simple to do, you can use it to teach quite a few concepts. The first and simplest concept is a chemical reaction. The definition of a chemical reaction, according to Encyclopedia Britannica, is “a process in which one or more substances, the reactants, are converted to one or more different substances, the products.”

In this experiment you are seeing not one chemical reaction, but two. When a reaction involves more than one step, each following the other, it is called a multi-step reaction. Here is what happens:

 

  • Vinegar contains acetic acid
  • Baking soda contains sodium bicarbonate
  • When acetic acid and sodium bicarbonate are combined, they form carbonic acid.
  • The problem with carbonic acid is that it is unstable. Unstable compounds cannot maintain their form and therefore will break down into component parts.
  • The component parts of carbonic acid are carbon dioxide and water.

 

The bubbles you see are actually carbon dioxide escaping. Because carbon dioxide is heavier than air, it will flow like a liquid when escaping a container. SixHands discovered this when he decided to add baking soda directly to the glass that held our vinegar—it over-flowed and bubbled all over my kitchen stove! (Fortunately, baking soda and vinegar actually make a good, non-abrasive cleaner for a flat-top stovetop.)

 

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This is why baking soda volcanoes flow like lava–because the carbon dioxide is heavier than the air around it.

 

To delve deeper into the science you can look at the equation for the reaction. This experiment shows a great example of a double replacement reaction. A double replacement reaction occurs when you start with two substances, AB and CD and these substances react in such a way that you end up with AC and BD.

 

For our experiment, we used acetic acid (HC2H3O2) —vinegar—and sodium bicarbonate (NaHCO3)—baking soda. So, consider it like this:

 

A = 2 Hydrogen and 1 Carbon

B = 1 Carbon, 2 Hydrogen and 2 Oxygen

C = 3 Oxygen

D = 1 Sodium, 1 Carbon and 1 Hydrogen

 

Then, if you look at the equation, you will see that they did indeed change sides.

 

First reaction:

HC2H3O2 (acetic acid) + NaHCO3 (sodium bicarbonate) = H2CO3 (carbonic acid) + NaC2H3O2 (sodium acetate)

 

The second reaction occurs almost immediately when the unstable carbonic acid breaks down into its components, namely H2O (water) and CO2 (carbon dioxide).

 

After you are finished with your experiment, take some time to allow your student to play with the baking soda and vinegar. Have them hold some baking soda in their hand and then pour a bit of vinegar on it. This will allow them to not only see the chemical reaction, but to feel it as well.

 

You can also provide them with some balloons, an empty water bottle, and a funnel. Ask them to fill the balloon with carbon dioxide without blowing into it. Given time, they will figure out that they can combine the vinegar and baking soda in the bottle to create the CO2, but how long will it take them to figure out the best way to combine these chemicals? (By placing the baking soda in the balloon and the vinegar in the bottle so they can get the balloon on the bottle before the chemical reaction begins to happen.)

 

When warm weather comes, you can take them outside and hand them baking soda, vinegar, a bottle, and a cork—this would be an experiment that requires some parental supervision! Pretty soon, you will have bottle rockets launching in your yard and kids who are quite excited about science.

 

Now, go have fun with science!

 

Michelle, a Virginia native, currently lives in Pennsylvania with her husband and three children. Active in Scouts, area homeschool groups, and with her family, she can be found on her blog, “Homeschooler on the Edge,” as well as Facebook, Twitter, and Pinterest.

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