Purple Brew: An Acid-Base Indicator

Next time kids say they don’t like vegetables, try out an experiment that will bring out the fun side of our leafy friends. Mom and Kiddo of  the blog What Did We Do All Day? shows us how to play with color in this demonstration that uses an acid, a base, and a vegetable. She suggests keeping some of the solution in the fridge for a rainy day and allowing kids to experiment on their own.

You will need:

• purple or red cabbage
• small and large glass jars
• baking soda
• water
• vinegar
• measuring cup
• 1/4 teaspoon

What to do?

1. Chop up a cabbage and simmer on the stove for 20 minutes to make a cool purple liquid (kids, please let a grown-up do this)
2. After the purple brew has cooled, collect some small and large jars. Place about 1/4 tsp baking soda and 1/4 tsp water in one jar, a small amount of vinegar in another and about 1/4 cup purple brew in a third.
3. Put some of the brew in a measuring cup and pour 1/4 tsp of the brew in each of the first small jars. What happens when you mix the purple brew with the different solutions?
4. In the jar filled with a 1/4 cup of purple brew,  pour about 1/4 cup vinegar. What happens?
5. Next, add 1/4 tsp baking soda to the same solution. What is your observation?

How does it work?

Red cabbage contains a chemical called flavin and flavin has the ability to change color based on the pH level of certain liquids. Nuetral solutions, (like water) are purple. Acid solutions, like the vinegar, turn will turn flavin red. Basic solutions, like the baking soda water, become blue.

You can check out Mom and Kiddo’s full post of this experiment HERE. Let us know what your results are when you make your own purple brew. What would happen if you tried different vegetables? What would happen if you used cream of tartar, lemon juice, salt, lemonade, or other materials from your kitchen pantry? Can you make your own litmus paper and test the pH of the solution?

Eggshell Geode Crystals

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This project comes to us from Melissa Howard who is a Mom, Blogger, and photographer. This project nicely demonstrates how real-life geodes are formed in igneous and sedimentary rock. It also demonstrates super-saturated solutions and shows a nice variety of crystal shapes and formations.

YOU WILL NEED:

• clean eggshells
• water
• a variety of soluble solids: table salt, rock salt, sugar, baking soda, Epsom salts, sea salt, borax, or cream of tartar
• small heat proof containers (coffee cups work well)
• spoons
• food coloring
• egg cartons and wax paper or mini-muffin tins

WHAT TO DO:

1. Crack the eggs for this project as close to the narrow end as possible. This preserves more egg to use as a container for the solution.
2. Clean the eggshells using hot water. The hot water cooks the lining and allows you to pull the skin (egg membrane) out of the inside of the egg using your fingers. Make sure to remove all the egg membrane, if any membrane stays inside the shell it is possible that your eggshell will grow mold and your crystals will turn black.
3. Use an egg carton lined with waxed paper or mini-muffin tins to hold the eggs upright.
4. Use a saucepan to heat the water to boiling. .
5. Pour half a cup to a cup of water into your heatproof container. If you poured half a cup of water into the container, add about a ¼ cup of solid to the water. Stir it until it dissolves. Likewise if you used a cup of water, add about ½ a cup of solid to the water. You wanted to add about half again the volume of the water as a solid to the mixture. When the initial amount of solid is dissolved continue adding small amounts of the solid until the water is super-saturated. Super-saturated simply means the water has absorbed all it is able to absorb and any solid you add will not dissolve.
6. Add food coloring.
7. Carefully pour your solution into the eggshell, filling it as full as possible without over-flowing it or causing it to tip.

Find a safe place to put your shells while the water evaporates. Crystals will form inside the eggshells as the water evaporates.

HOW DOES IT WORK?
Dissolving the crystals in hot water created what is called a “super-saturated solution.” This basically means that the salts took advantage of the energy of the hot water to help them dissolve until there was no more space between molecules in the solution. As the solution cooled, the water lost its energy and the crystals are forced from the solution to become a solid again. Since this happens slowly along with the evaporation, the crystals have time to grow larger than they were when the experiment started. Natural geodes in rock are form in much the same way as mineralized water seeps into air pockets in rock. This is also how rock candy crystals are formed.

You can visit Melissa’s great blog and see more pictures HERE.

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.

Do Birds Care What Color Their Food Is?

Would you want to drink green milk, how about orange mashed potatoes? The color of foods might affect just how much you want to eat them, but what about the birds in your neighborhood, would they care what color their food is? This sounds like an experiment in the making…. you coul even try this out for a science fair project, or just to learn something new while making your locals birds happy.

You will need:

• Several bird feeders that are the same size and type
• Light colored birdseed appropriate for the birds in your neighborhood
• Several colors of food coloring

QUESTION -  What color of birdseed, if any, will birds prefer the most?

RESEARCH: Ornithologists (scientists that study birds) are rather certain that most birds can see in color. One reason they think this is because birds themselves are very colorful.  In many species, male birds tend to be more colorful than females. This is likely because the males use their coloring to attract a mate,  while female birds tend to have less coloring to provide camouflage as they protect their eggs in the nest.  Before beginning a large experiment with lots of bird seed, you may want to put out a few small handfuls of different colored birdseed (see instructions for coloring birdseed below) to see how the birds near you react to different colored seed.  You may also want to refer to books and talk to an ornithologist to get their opinion about how birds see the word.

MAKE A HYPOTHESIS: Use the information that you’ve gained from your research and make a hypothesis based on your question. An example might be “Birds will eat more green birdseed than other colors.”

EXPERIMENT:  This is the fun part. You should get several bird feeders that are all the same size and type. Purchase a bird seed that is very light in color for this experiment.  To color the bird seed, pour it into a bowl and then add food coloring that you can purchase from the store. Mix it up well with a spoon and continue to add color until all the seed is colored.  You should sample at least a few colors and have one feeder with seed that has not been colored -  this is called the control and it will give you something to compare your results to. Now just hang them up outside in the same location, and wait for your feathered friends to show up. This works best in an area that birds are used to feeding from a feeder – it can take birds over a week to find new feeders.

COLLECT DATA:  Observe your bird feeder whenever possible, and keep track of how much seed is in each bird feeder each day. A ruler is helpful for this. You might also want to take pictures of the feeders and keep track of which kind of birds visit each feeder.  Over time, you should be able to see if one color of seed gets eaten more than others.

MAKE A CONCLUSION: Once your experiment is done, you will be able to go back to your hypothesis and see if it is correct. Remember,it’s not bad if your hypothesis was wrong. The main thing is that you’ve learned something from your experiment, and hopefully you had some fun doing it.

If you try this, let me know how it goes!

If you need inexpensive bird feeders, you can get some on-line HERE.

Oobleck – The Corn Starch And Water Experiment

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This may just be the easiest, messiest, and most fun science activity I know. It is a classic, and I have gotten several requests recently to post directions. You should know that if you try this activity and  you are not smiling and messy with corn starch goo at the end, then you are definitely doing something wrong. Also keep in mind that this is not just about fun, there is some pretty amazing science going on here.

You will need:

• Cornstarch (a 16 oz. box is good for every 2-3 participants – but more is always better)
• Water
• Food coloring (we always say it’s optional, but it does make it more fun – don’t use too much or you could end up with colored hands)
• A large bowl
• A camera – you’re probably going to want to take pictures.

Everyone should roll up their sleeves and prepare for some gooey fun.

1. This is easy. Pour the cornstarch into the bowl. Don’t rush to add water – take time to feel the cornstarch. Cornstarch does not feel like any other powder. It has a texture that can be compared to that of whipped cream. The grains of cornstarch are so small that they will fill into grooves of your fingerprints and make the prints stand out.
2. After you’ve taken-in the feel of the powder, it is time to add water. (You should add the food coloring to your water before adding it to the powder.) There are no exact formulas regarding how much water to add, but it will end up being about 1/2 cup (120 ml) of water per cup (235 ml) of cornstarch. The secret is to add the water slowly and mix as you add it. Don’t be shy here – dig in with your hands and really mix it up. This is usually when you notice that this is not your average liquid. Add enough water so that the mixture slowly flows on its own when mixed. The best test is to reach in and grab a handful of the mixture and see if you can roll it into a ball between your hands – if you stop rolling it and it “melts” between to fingers – success!

We’ll get the the science soon, for now just dig in and explore. Notice that the goo does not splash (or even move) if you hit it quickly. Squeeze it hard and see what happens. How long can you get the strands of goo to drip? What happens if you let the goo sit on the table for a minute and then try to pick it up? How does it feel? Hows does it move? Try bouncing a ball on the surface of the cornstarch. You get the idea – explore!

30 minutes later…

So now goo is everywhere and you’re thinking you should probably start cleaning. Actual clean up of the goo is a snap. A bucket of warm water will quickly get it off your hands. It will brush off of clothes when it dries, and it is easily cleaned off surfaces with a wet rag. Important: Make sure you do not dump the goo down the drain – it can get caught in the drain trap and take the joy out of your day of science. Dump it in the trash, or even mix it into soil in the garden.

Cornstarch grains under the microscope

Now for the science…
Our cornstarch goo (sometimes referred to as “oobleck” from the Dr. Suess book) is what scientists call a “Non-Newtonian” liquid. Basically, Sir Issac Newton stated individual liquids flow at consistent, predictable rates. As you likely discovered, cornstarch goo does NOT follow those rules – it can act almost like a solid, and them flow like a liquid. Technically speaking, the goo is a SUSPENSION, meaning that the grains of starch are not dissolved, they are just suspended and spread out in the water. If you let the goo sit for an while, the cornstarch would settle to the bottom of the bowl.

So why does this concoction act the way it does? Most of it has to do with pressure. The size, shape, and makeup of the cornstarch grains causes the cornstarch to “lock-up” and hold its shape when pressure is applied to it. People have filled small pools with oobleck and they are able to walk across the surface of it (as long as they move quickly.) As soon as they stop walking, they begin to sink.

I hope you get to try this out. Let us know how your day with non-newtonian liquids went. Comment here, or, even better, send us pictures to comment@sciencebob.com . Have fun exploring!

-Science Bob

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)

Procedure:

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!

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

Procedure:

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

Sarah 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.

How 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.

Make A Static Powered Dancing Ghost

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Today we were playing around with some balloons (which we often do when things get slow) and we had an idea to add a Halloween twist to a familiar static experiment. It is really quite a lot of fun and super simple. For this bit of spooky science you will need:

• A piece of tissue paper
• A balloon
• Scissors
• A head of hair
• Spooky Music (optional)

1. First cut out a ghost shape in the tissue as shown about 1.5 inches (4 cm) long and add some eyes with a marker. If you are using 2-ply tissues, peel apart the 2 layers to get the tissue as thin as possible. Cut out a few ghosts for more fun and place them on a flat surface.
2. Blow up the balloon and tie it. Then rub it really fast through your hair for about 10 seconds. This will add a static charge.

3. Slowly bring the balloon near the ghost, and the ghost will begin to rise toward the balloon. (Our ghost “arms” actually reached toward the balloon as we got it near.) If the balloon is charged enough, the ghost will rise and float right up to the balloon, even when it is several inches away. With a little practice, you can get the ghost to rise, float, and even dance around.

How’s it work?
When you rub the balloon through your hair, invisible electrons (with a negative charge) build up on the surface of the balloon. The electrons have the power to pull very light objects (with a positive charge) toward them – in this case, the tissue ghost!

Try it out and let us know how it goes.

CLICK HERE FOR MORE HALLOWEEN SCIENCE IDEAS.

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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!

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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