Lemon Chemistry: An Acid-Base Experiment

Kari Wilcher runs a great blog. She was looking to teach her pre-school children about the Scientific Method while trying out some kitchen chemistry at the same time. Her plan was to show a dramatic acid-base reaction using lemons, baking soda, and a little dish soap. She writes:

“I firmly believe that children are never too young to be exposed to the scientific method and should follow it. I have found that the scientific method is very easy for them to understand, and follow, when presented to them in a simple way. I like to use a rebus (picture) to help my non-readers understand the directions. I also use these “big” words: data, hypothesis, prediction, and observation. We, including Momma, wear goggles (from the dollar store) and a lab coat (a.k.a. dad’s white button up shirt) because we are real scientists doing real science experiments…and it just makes us cool.”

You will need:

  • Fresh Lemons
  • A knife
  • A small measuring cup & measuring spoon
  • Baking Soda
  • Liquid dish soap
  • A clear cup for the reaction

What to do:

  1. Roll the lemons on the counter like dough. This releases the juice inside the lemon.
  2. Cut the lemon in half (adults only, please) and carefully squeeze out the juice into a small measuring cup. Note how much juice was created from each lemon and put the juice aside.
  3. Into the empty glass place 1 Tablespoon of baking soda.
  4. Add 1 teaspoon of liquid dish soap to the baking soda. Stir these up a bit.
  5. Pour the lemon juice into the cup and stir. Now watch the lemon suds erupt!

How does it work?
This is a classic example of an acid-base reaction. This is often done with vinegar and baking soda, but we liked Kari’s “lemon twist.” The baking soda (a base) and the lemon juice (an acid) combine to release Carbon Dioxide gas. The liquid soap turns the bubbles into a foam that often erupts right out of the glass.

Try it out and let us know how it goes!

You can check out Kari’s full blog post of this experiment including the worksheets she created HERE.

Growing Bacteria For Science Fairs

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Testing for bacteria (germs) can be a great idea for a science fair experiment since there are so many possibilities for science questions, and because carrying out the experiment is pretty easy using widely available bacteria growing kits. Besides, who doesn’t like checking out bacteria and fungus?

All good science experiments start with a question – this is what you want to find out by experimenting. Here are a few example questions to get you started using the scientific method for growing bacteria:

  • Is a dogs mouth cleaner than a humans mouth?
  • Who has the cleanest mouth in the class?
  • Do antibacterial soaps really kill bacteria?
  • Which door handle in the school has the most bacteria?
  • Does toothpaste kill bacteria in your mouth?
  • Do dark socks create more bacteria in a shoe than white socks.
  • Do hand sanitizers work to kill bacteria?
  • What location in the school contains the most bacteria?
  • Is there more bacteria in tap water, bottled spring water, rain water, or pond water?

Step 1 – Ask A Question: Let’s imaging that you want to answer the question, “Which door handle in the school has the most germs?”

Step 2 – Research: You can’t just jump in and start experimenting. It’s important to do a little research. Ask the school nurse which door handle he or she thinks the most germs (bacteria) are. Observe and chart which door handles get the most use, survey friends and family to get opinions and write down the results. All this information will help you narrow down which door handles are the most likely to contain germs – and which ones you should choose to use in your experiment.

Step 3 – Make a Hypothesis: This is when you make a prediction based on your research. This is not an “I think…” prediction, it is a statement that will either be proven true or false based on experimenting. An example would be, “The handle to the nurse’s room contains the most bacteria.”

Step 4 – Experiment: This particular science experiment requires a simple bacteria testing kit. You would choose several door handles that you think might contain the most bacteria. These door handles are considered the Independent Variable in your experiment because each handle is independent and you control which ones are chosen. In a typical kit you would touch a separate cotton swab to each door handle, and then touch it to the bacteria growing Petri dish so that you would have one dish for each handle. Take good notes that would include when you collected each sample and where you collected the sample, and be sure to label everything well in any experiment.

Step 5- Collect Data: In this experiment, bacteria will start to grow in the Petri dish over the next few days, and you may be surprised by just how much gross bacteria is lurking in your school. Take good notes each day and determine which dish has the most bacteria growing in it.

Step 6 – Make Your Conclusion: This is when you decide if your hypothesis is correct. If your hypothesis was, “The handle to the nurse’s room contains the most bacteria,” your experiment will show if your hypothesis was right. It is not bad at all if your hypothesis is incorrect, what is important is that you answered your question from step 1. Now pat yourself on the back for your fine scientific discovery using the Scientific Method.

CLICK HERE for information about Bacteria Growing Kits.

Experiment While Making A Bouncy Ball

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Amy Huntley is a former science teacher and Mom that runs a great blog where she shares activities that she has done with her family. This exploration of polymers and bouncing balls  caught our eye and we were happy that Amy would share it with us. We’ve adapted it just a bit. The fun part is experimenting, and it is easy to make several of these and change up the recipe and check results. Note that this will not make a bouncy ball like you get at the grocery store, but ours bounced over a foot high and the ball has quite a unique feel to it.

You will need:

  • Borax (found in laundry section)
  • warm water
  • corn starch
  • glue (clear glue makes a see transparent ball and white glue makes an opaque ball)
  • 2 small mixing cups
  • a stirring stick (plastic spoon)
  • food coloring (optional)

ball3Procedure:

  1. Label one cup ‘Borax Solution’ and the other cup ‘Ball Mixture’.
  2. Pour 4 ounces (120ml) of warm water into the cup labeled ‘Borax Solution’ and 1 teaspoon of the borax powder into the cup. Stir the mixture to dissolve the borax.
  3. Pour 1 tablespoon of glue into the cup labeled ‘Ball Mixture’. Add 3-4 drops of food coloring, if desired.
  4. Add 1/2 teaspoon of the borax solution you just made and 1 tablespoon of cornstarch to the glue. Do not stir.
  5. Allow the ingredients to interact on their own for 10-15 seconds and then stir them together to fully mix.
  6. Once the mixture becomes impossible to stir, take it out of the cup and start molding the ball with your hands. The ball will start out sticky and messy, but will solidify as you knead it. Once the ball is less sticky, continue rolling between your hands until it is smooth and round!

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Amy adds:

“My boys loved making these “bouncy” balls. They are not super bouncy like the plastic super balls that became popular when I was a kid, but they are pretty bouncy and fun to play with. We discovered that on the carpet, they have a lot more bounce then they do on the kitchen floor. ”

These are also “temporary” bouncing balls and will lose their elasticity within a few days as they dry. Keeping your bouncy ball in a sealed bag will increase its bouncy lifespan.

The original “Super Balls” got their amazing bounce ability from compressed rubber under thousands of pounds of pressure.

How does it work?
This activity demonstrates an interesting chemical reaction, primarily between the borax and the glue. The borax acts as a “cross-linker” to the polymer molecules in the glue – basically it creates chains of molecules that stay together when you pick them up. The cornstarch helps to bind the molecules together so that they hold their shape better.

Make it an experiment
You can turn this activity into a true experiment by adjusting the amount of borax, glue, and cornstarch to get the highest bounce. You can also experiment to discover the best way to get the bouncy ball to keep its bounce over time. Have fun!

Check out Amy’s blog by clicking HERE.

Create Bubbles & Heat With Simple Chemistry

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Sarah Toney homeschools four active boys ages 2, 4, 6, and 8 in Tennessee. She recently tried out a simple experiment to help her boys observe a cool chemical reaction.

For Sarah’s experiment you will need:

  • 1 tsp (5ml) dry yeast
  • 1/2 cup (120 ml) hydrogen peroxide (should be handled only by adults)
  • stirring stick
  • thermometer

react1Procedure:

  1. Record the temperature of the hydrogen peroxide and place it in a small bowl.
  2. Add the dry yeast to the peroxide and stir
  3. Watch for changes in the mixture and the temperature

react2Sarah writes:
“The goal of the experiment was to observe a chemical change that produces heat. My boys got to see the different indicators that a chemical change was taking place- bubbling, fizzing and the temperature on the thermometer was going up. They were actually pretty amazed by this one. I keep listing the ways to tell if a chemical reaction has taken place….they’ve seen the bubbling, they’ve seen the gas given off…..I guess they didn’t really believe that heat could actually be created by just mixing 2 things.”

Another great part of this experiment is that the bubbles produced contain oxygen. This can be demonstrated by lighting and blowing out a wood match or splint. When the smoking match is brought near the bubbles, it re-ignites from the oxygen.

react3How does it work?
Hydrogen peroxide is H2O2. Than means it is water with an extra oxygen. The yeast contains a chemical called catayse that releases the oxygen creating the bubbles and it also releases heat (an exothermic reaction.) This is a simple version of our Fantastic Foamy Fountain experiment. The instructions for that experiment can be found HERE.

You can make this a true experiment by adjusting the amount of yeast and peroxide to try to get the greatest increase in temperature. You can also dissolve the yeast in water before adding it to the peroxide to see if that has an effect.

Visit Sarah’s blog post HERE.

The Lincoln High Dive – A Newton’s Law Experiment

Goat a few minutes? Here is a simple experiment that has impressed both students and adults that have tried it. It is also a great way to observe Newton’s First Law in action.

You will need:

  • A Lincoln penny (or other small coin)
  • A piece of card stock or stiff paper
  • A film canister (baby food jar, juice bottle, other  container with a mouth that is a bit wider than a penny)
  • Pencil or pen
  • Scissors
  1. Cut the cardstock paper into a long strip about .75 inches (2 cm) wide and form it into a hoop as shown. The paper should be stiff enough to hold the hoop shape on its own and the hoop works best when it is between 3-4 inches (8-10 cm) across.
  2. For dramatic effect, fill the film canister with water and place on a level surface.
  3. Place the hoop on the film canister as shown and balance the penny on the top of the hoop.
  4. Time for Lincoln’s big moment! Place a pencil through the center of the hoop and in one swift motion fling the hoop off to the side. If you do this correctly, the hoop will fly out of the way, and the penny will fall straight down into the canister with a splash. 10 points for Lincoln!

lincoln drop blog

This is science?
You betcha. For this demo, Newton’s first laws says, in general, that an object at rest will remain at rest unless acted upon by an outside force. The energy of your movement with the pencil was passed on to the hoop, making it fly out of the way, but the hoop was moving too fast and there was not enough friction to affect the penny (at rest) on top of the hoop. The penny ended up above the film canister with nothing to hold it up. It was about then that gravity took over, and pulled the coin straight down into the waiting water. Yep, Issac Newton and Abraham Lincoln, together in the name of science.

Try it out and post here to let us know how it goes! Experiment with various hoops and objects to make it different.

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Add Color To Flowers Using Science

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Many florists sell colored carnations, but I think it is more fun to make your own! And you can learn a little something about plants in the process. Best of all, you can make the flowers just about any color you want. Start off with some white carnations from your local florist. We paid about $1.oo each here in the US. (If you just want to demonstrate how plants transport water, and watch color move through leaves, you can also perform this experiment using celery.) You will also need:

Food coloring
Some small cups
Water

Decide what colors you would like the flowers to be and then add that color to your glass. You will need to add enough food coloring to create a strong color in the water, just a few drops of coloring will not have much of an effect. (Our blue looked more like black after adding enough color.)

two_color_carnationSnip the last centimeter of your carnation steam and place the stem in the colored water. Now just wait. Over the next day you will see signs of the coloring emerge in the petals, and even in the leaves. Our experiments have shown that sometimes the color emerges within a few hours, other times it takes a day or two. You can make green flowers for St Patrick’s day, red for valentines…you get the idea.

Mulitcolor? We tried splitting the stem with a razor (adults only, for that part please) and we then placed each stem into a different color of water. Sure enough the flower became multicolored (see above)…pretty cool. We wonder if it would work with three colors. If you try it, let us know.

So how does it work??
This is the science of TRANSPIRATION. It basically means that the plant draws water up through its stem. The water is then evaporated from the leaves and flowers through openings know as stomata. As the water evaporates, it creates pressure that brings more water into the plant – similar to drinking from a straw. Some trees can transpire dozens (even hundreds) of gallons of water on a hot day. How fast a plant transpires depends on temperature, humidity, and even wind. You may want to set up an experiment that tests the transpiration rate of the flowers by placing your plant-coloring set-up in different areas (sunny & dark, windy& still, dry & humid) and see which flower ends up with the most color – more color=more transpiration.

By the way, most flower shops do not color their flowers this way. There are many different breeds of flowers that are capable of producing a wide variety of flower colors. But we still think this way is more fun. If you try this out with your kids or your class, please let us know how it went.

Classroom fun with The Fizz Inflator

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What would the science world be without vinegar & baking soda? It would be a little less exciting at the Community School of West Seattle. Michelle Taylor teaches a K-2 program there and she decided to add a little science excitement to her classroom. With a little vinegar, baking soda, a bottle and a balloon, her students were able to to observe chemistry at work inflating the balloon. (Instructions for this experiment below)

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“You could hear the screams all through the school – it was so exciting.”

For instructions to this experiment, CLICK HERE.

To visit Michelle’s classroom blog, CLICK HERE.

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