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Wednesday, December 22, 2010
Happy Holidays!
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Thursday, December 16, 2010
Disappearing Shell Egg-speriment
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| An egg floats after its shell dissolves |
This activity complements my website's Ocean Acidification Kids' Page. Ocean acidification is happening because about a third of the carbon dioxide released from the burning of fossil fuels ends up in the ocean, where it reacts with ocean water, causing the water to grow more acidic.
The creatures most likely to be affected by ocean acidification are corals, shellfish, and some types of plankton that have shells or skeletons made of calcium carbonate. This is because acid is corrosive to calcium carbonate.
Bird eggshells are also made from calcium carbonate. In the following experiment you will see what happens when you put an egg in vinegar.
Ages 7 and up; click here for PDF
You will need:
egg
cup or jar
bowl
white vinegar
knife
Preparation
Place the egg in a cup, and cover with vinegar overnight.
Observation
Look at the egg. Do you notice anything unusual about it? For one thing, it now floats. For another, it is probably covered with tiny bubbles. Carefully pick it up and place it in a bowl. The egg’s surface feels soft because the calcium carbonate shell has dissolved, and all that is left is an opaque white membrane. The egg looks and feels hard boiled, but if you puncture the membrane, you'll see that it is raw.
Look at the egg. Do you notice anything unusual about it? For one thing, it now floats. For another, it is probably covered with tiny bubbles. Carefully pick it up and place it in a bowl. The egg’s surface feels soft because the calcium carbonate shell has dissolved, and all that is left is an opaque white membrane. The egg looks and feels hard boiled, but if you puncture the membrane, you'll see that it is raw.
What’s Happening?
Bird eggshells are made from calcium carbonate. Acid is corrosive to calcium carbonate, so vinegar dissolves the shell. All that is left is the membrane that lines the inside of the shell. Since the egg isn’t as dense without its shell, it now floats. Air bubbles form when the dissolved carbonate from the shell reacts to form carbon dioxide gas.
More to Try
Like eggshells, seashells are made from calcium carbonate. Try putting a seashell in vinegar and see what happens. Don’t do this with a seashell you like, however, because chances are it won’t look the same when you are done!
Bird eggshells are made from calcium carbonate. Acid is corrosive to calcium carbonate, so vinegar dissolves the shell. All that is left is the membrane that lines the inside of the shell. Since the egg isn’t as dense without its shell, it now floats. Air bubbles form when the dissolved carbonate from the shell reacts to form carbon dioxide gas.
More to Try
Like eggshells, seashells are made from calcium carbonate. Try putting a seashell in vinegar and see what happens. Don’t do this with a seashell you like, however, because chances are it won’t look the same when you are done!
Friday, December 10, 2010
Blowing Bubbles Makes Water More Acidic
This activity complements my website's Ocean Acidification Kids' Page. Ocean acidification is happening because about a third of the carbon dioxide released from the burning of fossil fuels ends up in the ocean, where it reacts with ocean water, causing it to grow more acidic.
In the following experiment you will make your own pH indicator from red cabbage. Using this pH indicator, you can see for yourself how carbon dioxide acidifies water. For more on acids, bases and pH, go to my Ocean Acidification Kids' Page.
Ages 7 and up; click here for PDF
You will need:
red cabbage
knife
large pot
stove
clear bowl
measuring cup
clear plastic cups
spoons
straw
chemicals to test (water, baking soda, vinegar, lemon juice, ammonia, soda pop, etc.; clear liquids work best)
You will need:
red cabbage
knife
large pot
stove
clear bowl
measuring cup
clear plastic cups
spoons
straw
chemicals to test (water, baking soda, vinegar, lemon juice, ammonia, soda pop, etc.; clear liquids work best)
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| from left to right: vinegar, lemon juice, Sprite, water, baking soda, ammonia |
Preparation
Place half the cabbage in a large pot and cover with water. Boil until the water turns a purplish green. After the juice has cooled, pour some into a clear bowl and dilute as necessary so you can see to the other side of the container. Congratulations! You have just made a pH indicator, a substance that changes color with pH.
Instructions
Set out a clear plastic cup for each chemical you plan to test, and pour a quarter cup of your pH indicator into each. Pour or spoon a little of each substance into the appropriate cup, and stir. Make sure to test some acids (like soda pop, vinegar, and lemon juice); some bases (like baking soda and ammonia); and water.
If you add water the pH stays neutral and the indicator has a blue color. Add a mild acid like fruit juice and the indicator turns purple. Add a stronger acid like vinegar and it turns pink. Add a base like baking soda or detergent and it turns green.
Watch carbon dioxide acidify water
Pour a quarter cup of pH indicator into a cup. Using a straw, blow bubbles into one of the cups for about a minute. Compare the color of the liquid in the two cups.
What’s Happening?
When you exhale, you breathe out carbon dioxide. The carbon dioxide reacts with the water to form carbonic acid, which acidifies the water and turns the pH indicator more blue.
Did you know?
Chemicals called anthocyanins are responsible for red or purple pigmentation in many other plants, including red cabbage, berries, grapes, and red fall foliage. Anthocyanins change color with pH, and anthocyanins extracted from almost any red pigmented plant can be used to make a pH indicator.
Place half the cabbage in a large pot and cover with water. Boil until the water turns a purplish green. After the juice has cooled, pour some into a clear bowl and dilute as necessary so you can see to the other side of the container. Congratulations! You have just made a pH indicator, a substance that changes color with pH.
Instructions
Set out a clear plastic cup for each chemical you plan to test, and pour a quarter cup of your pH indicator into each. Pour or spoon a little of each substance into the appropriate cup, and stir. Make sure to test some acids (like soda pop, vinegar, and lemon juice); some bases (like baking soda and ammonia); and water.
If you add water the pH stays neutral and the indicator has a blue color. Add a mild acid like fruit juice and the indicator turns purple. Add a stronger acid like vinegar and it turns pink. Add a base like baking soda or detergent and it turns green.
Watch carbon dioxide acidify water
Pour a quarter cup of pH indicator into a cup. Using a straw, blow bubbles into one of the cups for about a minute. Compare the color of the liquid in the two cups.
What’s Happening?
When you exhale, you breathe out carbon dioxide. The carbon dioxide reacts with the water to form carbonic acid, which acidifies the water and turns the pH indicator more blue.
Did you know?
Chemicals called anthocyanins are responsible for red or purple pigmentation in many other plants, including red cabbage, berries, grapes, and red fall foliage. Anthocyanins change color with pH, and anthocyanins extracted from almost any red pigmented plant can be used to make a pH indicator.
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| pH indicator color before (left) and after (right) blowing carbon dioxide bubbles into the liquid |
Friday, December 3, 2010
Homonym Word Play Coloring Page
The coloring page to the right features two of the silly sentences found in my Homonym Word Play game. Be sure to check out this month's Literacy Lava for the other eight! Click on image to enlarge, or click here for PDF.
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