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Science of Starch

11/29/2015

2 Comments

 
Author: Maddie Van Beek

Happy Thanksgiving! Just a few days ago, most of the country was celebrating Thanksgiving by having a turkey dinner. Traditionally, Thanksgiving dinners aren’t complete without mashed potatoes and gravy, but gravy is notoriously tricky to thicken to the right consistency. So how exactly do you make gravy, anyway? Let’s find out! ​
Picture
http://foodnetwork.sndimg.com/content/dam/images/food/fullset/2011/8/10/1/Thanksgiving-2011_IG1A02-homemade-gravy_s4x3.jpg
(For more information about Thanksgiving, it’s history, and the science around it, check out our Thanksgiving blog from last year: http://discoveryexpress.weebly.com/blog/happy-thanksgiving)

Some people swear by adding flour to the turkey drippings, while some say that the addition of corn starch is the secret to perfect gravy. The truth is, either ingredient will work to thicken gravy because both corn starch and flour contain starch, which is the one necessary ingredient to thickening a liquid such as gravy. 

​
How does starch work? http://www.thekitchn.com/food-science-how-starch-thicke-83665
Starch will thicken a liquid, but the catalyst for starch to thicken is heat (Remember, a catalyst is a helper that gets a reaction going). When heat is applied, starch grains take in liquid and swell, causing that liquid to become thicker. Without heat, starch grains won’t take in enough liquid to make a difference. 


Picture
http://hyperphysics.phy-astr.gsu.edu/hbase/organic/imgorg/starch.gif
To learn even more about the science of starch, check out this link: http://www.scienceinschool.org/2010/issue14/starch


Try to make your own gravy! What works better, flour or corn starch? Predict which ingredient will thicken the water quickest. You don’t have to go to the trouble of making real gravy to test out these ingredients. Just use warm water, and you’ll get a similar effect. 


YOU WILL NEED:
  • Two mugs or small bowls
  • Water
  • Corn starch
  • Flour


Here’s what to do: 
  1. Put 1/2 cup of water in each mug. 
  2. Microwave both mugs of water for about 1 minute (the water should be warm, not boiling). 
  3. Add 1 tablespoon of corn starch to the mug on the left, and 1 tablespoon of flour to the mug on the right. 
  4. Stir both mugs. Did the consistency change? 
  5. Keep adding flour and corn starch 1 tablespoon at a time, stirring after each spoonful. How many tablespoons of corn starch does it take for the liquid to get noticeably thicker? How many tablespoons of flour does it take? 
  6. You should have noticed that it took way more flour (about twice as much) to get the same thickness as the mug with corn starch. This is because corn starch is 100% starch, but flour is a mix of starch and protein. 


If you continue to add starch to water, you’ll get a gooey substance that’s fun to play with. You can roll the starchy goop into a ball, but when you quit moving it will slip through your fingers like liquid!

​If you’re looking for some messy fun, try out the first slime recipe in our blog: http://discoveryexpress.weebly.com/blog/two-times-the-slime-fun-with-polymers (you can continue to use corn starch instead of liquid starch). 



OR


If you want to try to make your own gravy, here’s a recipe to test out: http://saucepankids.com/index.php/2012/07/real-gravy-no-bisto-recipe/


Now that you know a little bit about starch and its properties, lets move on to our next activity. 


A few weeks ago, we did an activity called Iodine Clock Reaction. 


If you missed it, check it out here: http://discoveryexpress.weebly.com/blog/iodine-clock-reaction


In that activity, we combined iodine, starch, vitamin C, and hydrogen peroxide. Because of a chemical reaction, clear liquids suddenly became dark blue! In our activity today, we will use iodine to test certain substances for starch. If the substance contains starch, BINGO! the iodine will turn blue. 


YOU WILL NEED:
  • Iodine tincture (http://www.amazon.com/Cumberland-Swan-Iodine/dp/B00I3LNFT6)
  • Water
  • Dropper
  • Plastic cup
  • Polystyrene (styrofoam) cup
  • Apple
  • Potato
  • Bread
  • Paper
  • Tissue


Here’s what to do! 
  1. Create a work space where you can get messy. Either grab a large tray or cover your space with plastic or newspaper. This will be your testing area. 
  2. Dilute the iodine with water. The ratio of iodine to water should be 1:10. (For example, you could use 1 tablespoon of iodine and 10 tablespoons of water). If you need help, ask an adult! 
  3. Create a chart of substances that you will test for starch. You are going to test a plastic cup, styrofoam cup, apple slice, potato slice, piece of bread, paper, and tissue. If you want to test even more, add them to your chart. Then predict whether you think each substance has starch in it. Leave your final column blank to record your test results. Your chart may look something like this: 
Picture
4. Now that you have your iodine solution and your chart prepared, you’re ready to start testing materials! 

5. Fill your dropper with iodine solution. 


6. Place your first substance in your testing area. Squeeze a drop of iodine solution onto your first substance and observe. Did the iodine change colors? If not, the substance does not have starch. If the iodine changed to a dark blue, the substance must have starch! Fill in your chart after you test each material. 


7. After your testing is over, record your final observations. Were your predictions right? Were you surprised by your results? 

​
References: 
http://www.thekitchn.com/food-science-how-starch-thicke-83665
http://www.scienceinschool.org/2010/issue14/starch
http://www.primaryscience.ie/media/pdfs/col/exploring_starch.pdf
2 Comments

Elephant Toothpaste

11/22/2015

2 Comments

 
Author: Maddie Van Beek

Today, we are going to create a fun and foamy reaction that looks like a tube of toothpaste big enough for an elephant! You've created other reactions in the past, such as when we exploded a plastic bag or created film canister rockets. The most similar reaction to the one we are creating today is when we blew up a balloon with yeast. Yeast is going to be part of our reaction today. ​
Picture
https://www.questacon.edu.au/sites/default/files/assets/outreach/program/sqsc/assets/images/elephants_toothpaste_930w.jpg
If you missed our other ultra-reactive blogs, check them out here: ​
Acid / Base Reactions
Film Canister Rocket
Yeast as a Catalyst
What are chemical reactions? In a chemical reaction, two or more molecules interact, which causes a change in the molecules. Old bonds are broken and new ones are formed. 


Learn more about chemical reactions here: http://www.chem4kids.com/files/react_intro.html


There are more than one type of chemical reaction. An exothermic reaction releases heat or light. An example of this is wood burning in a fire. The wood burning releases heat and light. This is the opposite of an endothermic reaction. While an exothermic reaction releases energy, an endothermic reaction absorbs it. Today, you are going to be creating an exothermic reaction.


In order to create Elephant Toothpaste, you will use a catalyst to get the reaction going. A catalyst increases the rate of a chemical reaction. ​
Picture
http://www.theneighborhoodmoms.com/wp-content/uploads/2015/04/yeast.jpg
In this activity, yeast is your catalyst. When the yeast meets the hydrogen peroxide, it will cause the peroxide to quickly release oxygen.  ​
Picture
http://www.middleschoolchemistry.com/img/content/multimedia/chapter_6/lesson_5/hydrogen_peroxide_decomposition.jpg
The oxygen is released in the form of a bunch of tiny bubbles, thus creating foam that looks like toothpaste!
Vocab to remember:
  • Reaction
  • Exothermic 
  • Endothermic
  • Catalyst


Check out this amped-up version of Elephant's Toothpaste on Jimmy Kimmel. ​
Our reaction won't be THAT crazy, so don't worry! Let's get started on making our own Elephant's Toothpaste!


YOU WILL NEED:
  • Pan or tray
  • Empty 16 oz plastic bottle
  • 20-volume hydrogen peroxide (6% solution) : This can be purchased from a beauty supply store
  • One packet (one tablespoon) of dry yeast
  • Water
  • Liquid dish washing soap (like Dawn)
  • Small cup
  • Safety goggles 
  • Food coloring (optional)




Here's what to do!
  1. PUT YOUR SAFETY GOGGLES ON! Hydrogen peroxide can irritate your eyes, so let’s be careful! Ask an adult for help when you handle the hydrogen peroxide. 
  2. Place your empty 16 oz bottle in the middle of your tray or pan. 
  3. Carefully pour 1/2 cup of hydrogen peroxide into the plastic bottle.
  4. If you want your “toothpaste” to be colored, add a few drops of food coloring into the plastic bottle. 
  5. Measure out one tablespoon of liquid dish washing soap and dump it into the plastic bottle. Swish the bottle around to mix the soap in with the hydrogen peroxide. Set the bottle aside. 
  6. Pour 3 tablespoons of warm water into the small cup. 
  7. Add 1 tablespoon of yeast into the warm water and mix it in for about 30 seconds. 
  8. Here’s the fun part! Pour the yeast liquid into the plastic bottle and stand back! 
  9. FOAM FOUNTAIN MANIA! Feel the bottle. It should be warm. Remember, this is an exothermic reaction, so it produces heat. After the initial foam shoots out of the bottle, it will continue to ooze out like toothpaste for a while. 
  10. After the foam subsides, try it out again. This time, decide how you can make this activity an experiment. Choose a variable: You could alter the amount of yeast, the amount of hydrogen peroxide, or even the temperature of the water. Remember to only alter one variable at a time and make sure to record your observations!


References
  • https://sciencebob.com/fantastic-foamy-fountain/
  • http://www.stevespanglerscience.com/lab/experiments/elephants-toothpaste/
  • https://en.wikipedia.org/wiki/Exothermic_reaction
  • https://en.wikipedia.org/wiki/Endothermic_process
2 Comments

Iodine Clock Reaction

11/16/2015

0 Comments

 
Author: Maddie Van Beek

Picture
https://www.chem.wisc.edu/deptfiles/genchem/demonstrations/Images/12kinetic/clock.jpg
Today, we are going to mix together a few different substances to create a new substance of a different color! I know this sounds like common sense... when you mix together certain colors, they create a new color. For example, if I mixed together a red liquid and a yellow liquid, the result would be an orange liquid. But today is a little different! We are going to mix together a few substances–different substances that will cause a clear liquid to suddenly change blue! Don’t believe it’s possible? Let’s get going!


Before we move on to the activity, you must understand the reaction that will occur. The reason that your liquid will turn from clear to blue is because the substances involved cause a chemical reaction. That reaction makes all the difference! Otherwise, there would be NO WAY that two clear liquids would make blue! (For a review of chemical reactions, visit our blog about the reaction between vinegar and baking soda).



The reaction that we are working with today is called an Iodine Clock Reaction. You will be using iodine, starch, and Vitamin C to create this reaction. The starch is trying to turn the iodine blue, but the Vitamin C is battling the starch. This causes a delay in the reaction. Eventually, the starch defeats the Vitamin C and the color change occurs.

The delay is the reason it’s called a clock reaction. Initially, when the two liquids are mixed, nothing happens. It takes a certain amount of time for the reaction to occur, and then BAM! Your liquid will suddenly change colors!


Check out this video of the reaction that you will be creating:

YOU WILL NEED:
* Iodine tincture (2% from the pharmacy)
* Vitamin C tablet (1000 mg)
* Hydrogen peroxide (3% from the pharmacy)
* Liquid laundry starch
* 3 clear plastic cups
* Measuring spoons and measuring cups


Here’s what to do!
1. Label your cups A, B, and C.
2. Put a 1000mg Vitamin C tablet into a plastic bag and crush it up. You could use any hard object to help you crush it into a fine powder.
3. Carefully dump your Vitamin C powder into cup A. Add 2 ounces of warm water into the cup and stir until the powder is dissolved. Observe: What color is liquid A? What does it look like?
4. Before the next step, take a look at the iodine. What color is it?
5. Put one tablespoon of liquid A into the cup labeled B. Add one teaspoon of iodine. What happens to the color when these two liquids are mixed together? Set cup A aside.
6. Put 2 ounces of warm water into the cup labeled C. Add one tablespoon of hydrogen peroxide, then add 1/2 teaspoon of liquid starch. Use a spoon to stir the liquids together.
7. Now, let’s get going with this chemical reaction! Carefully pour the liquid in cup B into cup C. Pour the liquid back and forth between the two cups a few times and then wait patiently for a chemical color-changing surprise!


Extension: You just demonstrated an iodine clock reaction. How can you add a variable to create an experiment? Try changing the temperature of the water or the amount of Vitamin C or iodine to see if this affects the time it takes for the liquid to change colors! What about mixing? If you just let the liquid sit after you mix them, does it take longer to change? If you stir it more, does it change faster? Make sure to record your observations!


References:
https://en.wikipedia.org/wiki/Iodine_clock_reaction
https://sciencebob.com/rapid-color-changing-chemistry/

0 Comments

Oil spill cleanup!

11/8/2015

1 Comment

 
Author: Maddie Van Beek

You may have heard the saying “oil and water don’t mix.” It’s true! If you’ve never seen oil and water together in the same container, you will soon! The reason oil and water don’t mix is because they have different densities. Oil is less dense than water, which means that it weighs less. Because water is more dense, it sinks to the bottom of the container. Because oil is less dense, it will always float to the surface of the water.
​
Test it out!

Fill an empty water bottle about three-fourths full with water. Add about a half-cup of oil to the bottle. What happens? The oil just sits right on the surface. Tip the bottle upside-down. The oil rises to the top and the water sinks to the bottom. What do you think will happen when you shake up the bottle? Try it out! It may look like the oil and water have mixed, but it’s only temporary. You probably see that the bottle looks to be filled with a bunch of bubbles. This is the oil broken up by the vigorous shaking. Eventually, all the oil will rise back to the top.


We took this demonstration a step further a few weeks ago when we made our own lava lamps out of colored water and vegetable oil: http://discoveryexpress.weebly.com/blog/make-your-own-lava-lamp.


You just saw a small example of how oil is insoluble in water. Insoluble means that the oil does not dissolve or mix in with water. Why would this matter in real life? Oil is a commodity that is always being shipped across the ocean to different areas. Sometimes, there are mistakes and oil is spilled into the ocean, possibly because of a leak in an oil tanker. Why would this matter? While oil sits on top of the water because it’s insoluble, it is extremely difficult to remove from the water. That’s what we are going to focus on today!


Check out this link to learn more about oil spills and why they are a BIG DEAL: http://www.kidzworld.com/article/24170-oil-spills-sad-but-true


How do we deal with oil spills? Read this article about how oil is removed from water: http://www.livescience.com/32524-how-are-oil-spills-cleaned.html


The question of the day: What is the most effective way to remove oil from water? In this experiment, you will use different materials to act as surface skimmers, the first of the four oil spill cleanup methods you just read about on livescience.com.


YOU WILL NEED:
  • Water
  • Vegetable oil
  • Clear container
  • Dry-erase marker
  • Tools: Cotton balls, gauze, polypropylene cloth


Here’s what to do!
1. Fill your clear container half full with water.
2. Add vegetable oil to the container of water until you have at least a half-inch layer of oil sitting on the top. This is your oil slick.
3. Use a dry-erase marker to mark the where the surface of the oil is. This is your reference point to see how much oil you can remove with your materials.
4. Make a prediction about which tool will work best for removing the oil from the water. Why do you think this will work the best?
5. Make a chart to record your observations. It may look something like this:
Picture
6. Test out each material individually and record your observations in your table. Try to remove all the oil with the cotton balls. Is it possible? How long does it take? Stop after 10 minutes and see where you’re at. Look at the reference point to see how much oil you were able to remove. 

7. Add more oil to the container until the level is the same as it was before you used the cotton balls. Now, test out the polypropylene cloth. How effective is this material? Does it take more or less time to remove the oil? Were you able to remove more oil? 


8. Last, try out the gauze. Record your observations as you did with the first two materials. 


​9. Draw conclusions and record your final thoughts. Which tool worked the best to remove the oil?  


Extension: You’ve tried removing oil from water, but sometimes when oil spills occur, the oil that spilled in the ocean makes it to shore and coats the sand. How difficult is it to remove oil from sand? Will the same techniques work? Fill a cup with sand and then dump half a cup of vegetable oil into it. Use a spoon to stir the oil into the sand until its well blended. Now, test all the methods out to see how much oil you can remove. You could even try to use soap! Which method was most effective in removing the oil from the sand? 


References: 
  • http://www.funology.com/oil-spill-clean-it-up/
  • http://weirdsciencekids.com/Oilspillexperiment.html
  • http://www.mmaiche.org/Experiments/OilSpill.pdf
1 Comment

Halloween Science

11/1/2015

0 Comments

 
Author: Maddie Van Beek

Halloween may be over, but that doesn’t mean you can’t still have some spooky fun with Halloween science activities! 


1. Use your colorful candy to try out candy chromatography! 


What exactly is chromatography? 


Chroma means color and graphein means to write. 


There are a few different kinds of chromatography, but today you are going to be dealing with paper chromatography. When you use paper chromatography, you can separate different inks or dyes into their individual components. For example, a black marker actually has many different colors of dye to create black ink.

​Watch the video below to watch how paper chromatography can be used to separate black ink into its individual colors: 

You can use this same idea to separate the dyes of your favorite candies! 


YOU WILL NEED
  • M&Ms or Skittles
  • Coffee filter paper
  • A tall glass 
  • Water 
  • Table salt 
  • Pencil
  • Scissors
  • Ruler 
  • 6 toothpicks 
  • Aluminum foil 
  • 2 liter bottle with cap


Check out our blog about candy chromatography here for instructions: http://discoveryexpress.weebly.com/blog/candy-chromatography


2. Create your own glowing beverages! 


Did you know that tonic water glows under a black light? The reason that it does this is because of one special ingredient: quinine. 


Why is quinine fluorescent? Read the link below to find out! 
Why is quinine fluorescent?
Now that you know about quinine, do you know what a black light is? Why is a black light any different from a regular light? They might appear the same as any other light bulb, but they function very differently. Black lights actually produce ultraviolet light. When you turn a black light on, it causes white things to glow in the dark. 


Read about black lights in the link below to find out how they work: ​
How do black lights work?
YOU WILL NEED
  • Tonic water
  • Ice cube trays
  • Sprite or 7-up
  • A black light

​
Here’s what to do! 


The instructions for this activity are very simple. Make ice cubes out of tonic water and then put them in any light colored drink such as 7-up or Sprite. Turn on a black light, turn off the lights, and watch your beverages glow an eery blue!


3. Make pumpkin slime!


The slime that you will be creating is a non-newtonian fluid. Newtonian fluids behave as you would expect a liquid to behave. For example, when you hit water, it gives way. You can easily put your hand through it without much resistance. Non-newtonian fluids sometimes act like a solid and sometimes act like a liquid. When you hit a non-newtonian fluid, it resists the impact. How can that be? 


Watch this video to see people experiment with non-newtonian fluid. They even try to bike across it! You’ll be amazed at its power to resist stress. ​
YOU WILL NEED:
  • One pumpkin
  • Cornstarch 
  • Mixing bowl
  • Spoon
  • Cookie sheet or pan
  • Food coloring (optional: your pumpkin will already color your slime an orangey tint)
Check out our blog from a few weeks ago to learn more about non-newtonian fluids and create your own pumpkin slime: http://discoveryexpress.weebly.com/blog/pumpkin-slime




References:
https://sciencebob.com/free-halloween-science-ideas/


http://www.scientificamerican.com/article/shining-science-explore-glow-in-the-dark-water/


http://science.howstuffworks.com/innovation/everyday-innovations/black-light.htm
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