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Turn milk into plastic and bones into rubber!

7/26/2015

1 Comment

 
Author: Maddie Van Beek

In the last few weeks, we have conducted various experiments that use vinegar. Two weeks ago, you made dirty old pennies shine like new (http://discoveryexpress.weebly.com/homeblog/a-simple-solution-to-your-dirty-pennies), and last week, you created a film canister rocket (http://discoveryexpress.weebly.com/homeblog/make-your-own-film-canister-rocket) using either antacid or vinegar and baking soda for fuel! If you did either of those experiments, you know that vinegar is acidic. That is what allows it to react with other basic substances such as baking soda. 




To learn more about acid-base reactions, check out this blog: http://discoveryexpress.weebly.com/homeblog/experimenting-with-eggs-acid-base-reactions-and-osmosis




Today, you are going to use vinegar in two different experiments that show how vinegar can react with calcium. In the first experiment, you will create plastic out of milk. Sound crazy? Let’s find out more. 



Picture
http://www.cdn.sciencebuddies.org/Files/5764/5/Milk-Curds-Drained.jpg


Okay, there isn’t ACTUALLY plastic in your milk. The chunks that you see in the image above are a substance called casein. Casein is found naturally in any mammal’s milk. The word casein comes from the latin word caseus, which means cheese. The cow milk that you drink has protein, and 80% of that protein comes from casein. Casein also contains the calcium that you get from drinking milk. 

Picture
http://www.healthcare-online.org/images/10403408/607271-cow.jpg


At the end of your activity, your result will look something like this: 


Picture
http://www.cdn.sciencebuddies.org/Files/5765/5/Casein-Lump.jpg


You don’t usually encounter chunks of casein in your milk. How will you end up with this result? As you know, the acid in vinegar reacts with other substances such as calcium. In the following activity when you mix vinegar with milk, the casein protein in the milk refuses to mix with the acid in the vinegar. Thus, you are left with blobs of casein that will harden into a plastic-like substance. 




YOU WILL NEED: 

  • Milk
  • Sauce pan
  • Vinegar
  • Strainer
  • Bowl
  • Spoon 
  • Adult help



Here’s what to do! 

  1. Measure one cup of milk and add it to the sauce pan. Have an adult help you heat up the milk until it is hot, but not boiling. Watch the milk carefully so it does not boil!
  2. Once the milk is hot, carefully pour it into the bowl. 
  3. Use a teaspoon to add four teaspoons of vinegar to the hot milk. 
  4. Use a spoon to stir the vinegar milk mixture for one minute. 
  5. Predict: What do you think the vinegar has done to the milk? What will happen when you pour the milk through the strainer? Write your predictions down in your observation notebook. 
  6. Place a strainer in the sink and pour the vinegar milk mixture through the strainer. What do you see? Take pictures, sketch what you see, and write down your observations in your observation notebook. 
  7. You should have seen a bunch of weird blobs left in the strainer. Once these blobs cool off, rinse them off in cool water and press them together. Now you can form them into any shape you want and it will harden into a plastic-like material in a few days! 



Follow-up: 

  1. What is casein? 
  2. What were the blobs left over after you dumped the vinegar milk mixture through the strainer? 
  3. Why were those blobs created? 
  4. Is there actually plastic in milk? If not, what is it? 



Extension: If you want to make this activity into an experiment, try some of the following ideas! 

  • Use another acidic substance to see if it works better or worse than vinegar. 
  • Alter the amount of vinegar to see if it creates more or less casein blobs. 
  • Use different kinds of milk to see if all milk has the same amount of casein. 



In the next experiment, you will use vinegar to break down the calcium in a chicken bone. A once solid bone will become bendy and flexible. Why does this happen? 




Predict: Why would vinegar make a bone flexible? 




When you leave a bone in vinegar, a reaction happens! The acid in the vinegar is strong enough to eat away the calcium in the bone over time. You may have seen this same reaction happen when you dissolved eggshells (http://discoveryexpress.weebly.com/homeblog/experimenting-with-eggs-acid-base-reactions-and-osmosis). 




As you’ve probably heard from your mother, calcium keeps your bones strong! That calcium is what keeps your bones from bending or easily breaking. Once that calcium is removed, there is nothing to keep the bone rigid and strong. Of course, the calcium doesn’t just disappear; the acid in the vinegar frees the calcium from the bone and it becomes dissolvable in water. The once hydrophobic (water-fearing) calcium becomes hydrophilic (water-loving). Once this happens, all that is left is the flexible tissue that makes up the bone. Now you know why it’s important to drink your milk! (Or at least get some good source of calcium in your diet!)

Picture
http://www.kingsnews.org/uploads/article/230x136/imagescael1kd3b513f0501182d8c581d85259a51b6bf.jpg





Now that you understand how vinegar breaks down calcium, try it out for yourself! 





YOU WILL NEED:

  • Chicken bone
  • Vinegar
  • Tall glass or jar



Here’s what to do! 

  1. Whenever you have chicken, save a leg bone. (Other bones will work, but the leg bone is nice and rigid to start out with). 
  2. Remove any remaining meat or skin from the bone and rinse it off in the sink. 
  3. Record observations about the bone in your observation notebook. What does the bone feel like? Can you bend it at all? 
  4. Put the bone in a tall glass or jar. Dump vinegar into the container until it completely covers the bone. No part of the bone should be sticking out of the vinegar. 
  5. Cover the glass or jar and leave it to sit for 3 days. 
  6. PATIENCE!!!
  7. Times up! Dump out the vinegar and remove the bone from the container. How has it changed? Record your observations in your notebook and compare the bone now to how it was three days ago. 



Follow-up questions: 

  1. Did the bone really turn into rubber? Of course not! What happened to it? 
  2. Why would vinegar change the quality of the bone? 
  3. What kind of reaction occurred? 



Extensions: 

  • Do you think other acids would work the same way as vinegar? What if you put the bone in orange juice? 
  • Would thicker bones take longer to become bendy? Would smaller bones become bendy sooner? 
  • If you put the leg bone back in vinegar, will it become even more bendy? Does time spent in vinegar affect the bendiness of the bone? 






References: 

http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/acidbase.html

https://en.wikipedia.org/wiki/Casein

https://sciencebob.com/make-plastic-milk/

https://sciencebob.com/bend-a-bone-with-vinegar/

http://www.sophisticatededge.com/why-does-vinegar-dissolve-calcium.html

1 Comment

Make your own film canister rocket! 

7/19/2015

0 Comments

 
Author: Maddie Van Beek

In past experiments, you have learned about the gas carbon dioxide. For example, you may have tried blowing up a balloon with vinegar and baking soda, dissolving an egg shell or exploding a Ziplock bag. 

Today, we are going to use water and an antacid tablet to turn a simple film canister into a rocket! Why will this work?

When you add water to an Alka-Seltzer tablet, it starts a chemical reaction. The tablet dissolves, fizzes, and creates carbon dioxide gas. The reason this happens is because Alka-Seltzer tablets contain sodium bicarbonate (NaHCO3) and citric acid. When sodium bicarbonate atoms dissolve in the water, they breaks apart into separate sodium (Na+) and bicarbonate (HCO3-) ions. Then those bicarbonate ions react with the citric acid to create carbon dioxide gas. When carbon dioxide gas is contained within a film canister (or any enclosed space), the pressure increases as that gas is produced. Eventually, that pressure has to be released! 




If you’ve ever used vinegar and baking soda to create a volcano, you’re seeing the very same reaction between the acid in the vinegar and the sodium bicarbonate in the baking soda that you do when you combine Alka-Seltzer and water. 



Now that you understand the chemical reaction that will fuel your rocket, let’s get started! 



YOU WILL NEED:

  • Film canister (you should be able to find these at any location that develops film)
  • Alka-Seltzer or other brand fizzing antacid tablets
  • Water
  • Safety goggles



Here’s what to do!

  1. Put on your safety goggles!
  2. Break the antacid tablet in half. You won’t need the whole tablet for this demonstration. 
  3. Remove the lid from the film canister and set it aside. 
  4. Add 1 teaspoon of water into the film canister. 
  5. Now, you are going to have to move quickly! Place the half tablet of Alka-Seltzer into the film canister and snap the lid on tight. 
Picture
http://sciencebob.com/wp-content/uploads/2014/11/filmcanister.png


6. Step back and watch! What happened?!
Picture
http://www.thenakedscientists.com/HTML/uploads/RTEmagicC_FilmCannister-pop.png.png


Within a few seconds, the lid of the film canister should have popped off. If you want to create an even bigger result, flip the canister upside down after step 5 and watch the canister fly high into the air! If you choose to try this, make sure you go outside so you don’t make a mess or hit anything with a flying film canister rocket! 
Picture
https://www.questacon.edu.au/sites/default/files/assets/visiting/spectacular_science_show/assets/images/popoff.gif


Extensions: 

What if you add more antacid to your canister? Will it fly higher? Does the amount of antacid affect the time it takes the rocket to launch? 



Check out the video below. They chose to use vinegar and baking soda rather than the antacid tablet. How did they get the same result? Try it both ways and see if one works better than the other! 








Do you think creating a nosecone or fins would make your rocket fly higher or straighter? Try it out! 




References:

http://www.sciencebuddies.org/science-fair-projects/project_ideas/Chem_p026.shtml#background

http://sciencebob.com/build-a-film-canister-rocket/

http://www.howcast.com/videos/429799-how-to-make-a-film-canister-rocket/

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A simple solution to your dirty pennies!

7/11/2015

0 Comments

 
Author: Maddie Van Beek

Have you ever noticed the difference between an old and a new penny? The newer pennies look so much shinier than the old ones! Why is that? You might think the old pennies just have dirt and grime built up on them over the years, but they are also covered with copper oxide. Remember last week when we learned about atoms? (If not, check out last week’s blog HERE). 




Everything in the world is made up of atoms! Sometimes, atoms combine with one another to make new materials. Copper atoms can combine with the oxygen in the air to make copper oxide. Copper oxide is what makes older pennies look so dull. 



As you can see in the image below, the 1995 penny is much shinier than the 1944 penny.

Picture
http://tikalon.com/blog/2012/1995_1944_pennies.gif
Today, you are going to learn how to remove the copper oxide from old pennies and make them shine like new! 



YOU WILL NEED:
  • Large, non-metal bowl
  • 1/4 cup white vinegar
  • 1 teaspoon salt
  • Pennies (make sure they are dull ones, not shiny ones)
  • Nuts and bolts (screws or nails also work, but be careful!)
  • Paper towel
  • Marker
  • Clock or timer



Here’s what to do! 
  1. Pour 1/4 cup white vinegar into the bowl. 
  2. Add 1 teaspoon of salt into the vinegar and mix it up until the salt completely dissolves. You now have a vinegar-salt cleaning solution. 
  3. Place about 10 pennies in the bowl of solution. Set your clock or timer for 10 seconds. 
  4. Remove all 10 pennies from the solution and set 5 of them on the paper towel marked “not rinsed.” 
  5. Rinse the remaining 5 pennies off with water and set them on the paper towel labeled “rinsed.” 
  6. Wait 1 hour before you come back to the pennies. While you’re waiting, place a few nuts and bolts into the same bowl of solution that you had the pennies in and set the timer for 10 minutes. What happened to the nuts and bolts? They changed color! This happened because when you dissolved the copper oxide in the vinegar-salt solution, some of the copper atoms dissolved with it. When the copper atoms separated from the penny, they left some of their electrons behind, so they went from neutral copper atoms to positively charged copper ions. When you put the nuts or bolts into the solution, the same thing happened to the steel. Some of the steel atoms left the nuts and bolts and became positively charged steel ions. Because the nuts and bolts now have an excess of electrons, they became negatively charged. What do you know about opposite charges? They attract! The negatively charged nuts and bolts attract the positively charged copper ions that are floating around, so they end up coating the nuts and bolts with a thin layer of copper. 



Your results should look similar to the image below: 

Picture
http://3.bp.blogspot.com/-BkHIGQcJBjc/U3mPGuZwHFI/AAAAAAAAVCc/UKpcfg0QGss/s1600/copperplating.jpg
7. Now that it’s been an hour or so, go back to your pennies! Do the rinsed pennies look different than they did before you put them in the cleaning solution? Record the differences in your observation journal. They should look shiny and clean! 


8. Now look at the unrinsed pennies. What do they look like? Very different from the rinsed pennies! Record the changes in your observation journal. 



What happened to the unrinsed pennies? They turned a bluish-green color! You should have gotten a result somewhat like the image below. 

Picture
http://buggyandbuddy.com/wp-content/uploads/2013/06/green-pennies1.jpg
Why would rinsing the pennies with water make such a big difference--they all were dunked in the cleaning solution, right? The vinegar salt solution dissolved the copper oxide layer off of all the pennies, but the unrinsed ones underwent a new reaction. The copper atoms combined with oxygen from the air and chlorine from the salt to form the bluish-green stuff you now see, a compound called malachite. 

Picture
https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Malachite_needles.jpg/250px-Malachite_needles.jpg


Experiment!


Now that you know vinegar and salt work as a cleaning solution to dissolve the copper oxide off of pennies, try other acids to see if they work just as well! For example, you could try using lemon juice to see if it works better or worse than vinegar. What other acidic liquids can you think of? You could also adjust the amounts of salt to see if that makes a difference. Remember to record your findings in your observation journal! Happy experimenting!





References

http://sciencebob.com/clean-pennies-with-vinegar/


https://www.exploratorium.edu/science_explorer/copper_caper.html


https://en.wikipedia.org/wiki/Malachite

Further Reading:
​https://www.tipsbulletin.com/cleaning-with-vinegar/
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Bend a stream of water with static electricity!

7/5/2015

3 Comments

 
Author: Maddie Van Beek
Picture
http://tutorinlosangeles.com/wp-content/uploads/2012/12/garfield_static.gif
Did you know you can bend water? It’s true! All you need is static electricity! But how do you create that? 



Have you ever slid down a slide only to find your hair sticking straight up afterwards? That’s static! I’m sure you’ve heard of static before, but what does it really mean? 

Picture
http://www.blogcdn.com/www.diylife.com/media/2010/12/dog-static-electricity-fur-laundry-basket-590jn121710.jpg
In order to understand static electricity, you must first understand the atom. Everything in the world, including YOU, is made up of atoms. An atom is the most basic unit of an element. If you were to break an iron bar in two, the two pieces are still made up of iron atoms. If you continued to divide the iron bar in two until you could only see the pieces under a microscope, the pieces would still be made of iron. The smallest amount of iron would be one atom of iron. But, if you tried to break apart that one atom, it would no longer be iron. Why? Because one atom is the basic unit of any element. 



That’s not to say that atoms cannot be broken apart--they can! Each atom is made up of three kinds of particles--the protons, neutrons, and electrons. The protons and neutrons are tightly packed together in the center of the atom called a nucleus. That’s the ball you see in the diagram below. The electrons are much farther away and actually rotate around the nucleus. An atom is kind of like a solar system! Think of the nucleus as the sun and the electrons as the much smaller planets in orbit around it. 

Picture
https://upload.wikimedia.org/wikipedia/commons/d/d8/Atom_diagram.png
What does this have to do with static? Well, each of these small particles carries a charge. 



Neutrons = Neutral charge (no charge)


Protons = Positive charge


Electrons = Negative charge





This carbon atom has 6 protons and 6 electrons, so it has an overall neutral charge. 

Picture
http://astrobob.areavoices.com/files/2013/03/Atom-model-carbon-Uni-today-400x333.jpg
Sometimes, electrons can transfer from one object to another. When an object gains electrons, its charge becomes negative. When an object loses electrons, its charge becomes positive. As you can see below, an electron left a sodium atom and transferred to a chlorine atom. What happened to the charges of the atoms? Why? 

Picture
http://www.mun.ca/biology/dmarshall/02-14-IonicBonding-L.gif
One way that objects transfer electrons is through rubbing against one another. That’s what you’re going to do in the activity today!  



As you probably know, objects with opposite charges attract each other and those with like charges repel each other. When an object becomes negatively charged, it can also attract objects with a neutral charge. For example, when you place a balloon against a wall, it falls to the ground. But when you rub a balloon against your hair, it gains electrons. Then when you place it on a wall, it sticks. This is because the negatively charged balloon is attracted to the protons in the wall. 

Picture
http://www.sciencemadesimple.com/img_static/balloont.gif
Activity: This is a very simple demonstration of how static electricity can be used to bend a stream of water. This happens because the comb or balloon has gained electrons and has a negative charge. The negatively charged item then attracts the neutral charge of the water. 



YOU WILL NEED

  • Balloon
  • Plastic comb
  • Sink 
  • Dry hair 



Here’s what to do! 

  1. Turn on the faucet so a steady but narrow stream of water is flowing. It should be only a few millimeters across, but make sure it’s steady enough that it’s not just water droplets. 
  2. Run the plastic comb through your hair about ten times. 
  3. Slowly move the comb toward the stream of water, but be careful not to touch it. What happens? 
  4. You should have seen the stream of water bend towards the comb, almost like magic! But this isn’t magic, it’s just simple science!



Extension: You can also do this experiment with a balloon instead of a comb. You would blow up the balloon and rub it against your hair for a few seconds, then bring it close to the stream of water just like you did with the comb. Try using the balloon to see if you can get the same results. 




References

http://www.sciencemadesimple.com/static.html

https://en.wikipedia.org/wiki/Static_electricity

http://www.sciencekids.co.nz/experiments/bendingwater.html

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