Aluminum Steel Tin Acid Electricity Rust
Why is it a bad idea to buy dented cans?
|
|
|
|
|
This Week's Experiment - #288 No Dented Cans
One of the things that I have enjoyed on this trip is doing the cooking. I
really like to cook, both for the fun of making things that taste good and
for the science involved. We went into Whangarei to get groceries, and while
we were shopping, I noticed some dented cans. That gave me the idea for this
week's experiment. Why is it a bad idea to buy dented cans? Because they
don't look as nice? Because some of the food inside might be dented too? To
find out, you will need:
a penny or other copper coin
some aluminum foil
some catsup
a plate or saucer
Tear a strip of foil about an inch wide and 3 inches long. Place it on a
plate. Put the penny on one end of the strip. Squirt a blob of catsup on
top of the penny and then fold the other end of the foil over, so that it
squishes into the catsup. Crease the fold enough so that it will stay in
place. This should give you sort of a foil and penny sandwich. Looking from
the side, you should have foil on the bottom, with a penny on top of that,
then catsup and then the other end of the foil. Set the plate in a warm
place where it will not be disturbed.
The next day, rinse the catsup off the foil and examine it carefully. In the
area where it was touching the catsup, it is full of holes! Oh no! If
catsup does that to aluminum foil, think what it is doing to my stomach! I
can never eat French fries again!
Yes, the catsup does contain acid. ACID!!!! Don't get too excited. The
acid is vinegar. Read the label and you will see. How did vinegar do that?
Well, the acid is not responsible, or at least, not directly. The culprit is
electricity.
Electricity? I did not tell you to plug it into the wall. DON'T DO THAT!!!
It would be very dangerous, and besides, you don't need to. This experiment
makes its own electricity. The copper penny and the aluminum foil, connected
by a conducting solution (catsup) form an electric cell, which will produce
about 1/2 of a volt of electricity. You can't light a light with it, as the
amperage is very small, but it does produce an electric current. If you cut
through the foil strip in the center and connect a probe from a volt meter to
each piece of foil, you should be able to measure about 1/2 of a volt.
In the process of producing the electric current, the penny is stealing
electrons (tiny, negatively charged pieces of atoms) from the aluminum. This
changes the aluminum and lets it dissolve in the acid in the catsup.
OK, so now we know how to dissolve holes in aluminum, but what does that have
to do with dented cans. Cans are made of steel. The problem with steel is
that it rusts when it comes in contact with water and oxygen. Since most of
the foods that we put into cans are wet, they would quickly rust the can. To
solve this, the steel cans were plated. That means that the inside was
covered with a thin coating of the metal tin. Tin is not strong enough to
make a good can, but it does not rust. The tin coating on the inside keeps
the can from rusting and the steel give the can its strength.
If a can is dented, the tin layer can be cracked, letting the liquid come in
contact with the steel. Now you have two metals (steel and tin) in contact
with a conducting solution (the liquid in the can). The can of food begins
to produce electricity. It also starts to oxidize (rust) the metal in the
can, producing a hole and letting the food inside spoil. That is why we
don't buy dented cans.
These experiments are from Robert Krampf - The Happy Scientist
Education Posters at AllPosters.com | Clearance Posters
|
|
|
|
|
Nicholas Academy Index
|
|
Roman numerals, addition, multiplication, order of statehood, state and world capitals, order of presidents, chemical elements, parts of speech, spanish numbers.
|
Explore animation, filmmaking, build online cities, create and share works of art, write stories, create your own web site, read creativity articles.
|
Math games, quizzes, fun websites, printable charts, coloring books, tools. Algebra, geometry, fractions, multiplication.
|
Science games and quizzes, fun science websites, posters, coloring books, experiments, forensics labs and more.
|
Play language arts games, improve your vocabulary, create customized puzzles, make your own book! Download free software in the form of shareware, freeware, and demos.
|
|
Play music games, take free music lessons, explore music theory and history, find great posters.
|
Test your knowledge with these fast, fun, and educational quizzes. Roman numeral addition, world capitals, presidents in order, the elements, world flags, and more.
|
Templates, ideas for personal, educational, children's, business sites, design tips and tools, registration and hosting information, step-by-step instructions, quick and easy web page, web building just for kids.
|
Coloring books, countries of the world, games and quizzes, software downloads, posters, computer jigsaw puzzles, printables.
|
Science can be fun and understandable. Free Experiment of the Week, featuring experiments that are unusual, safe, dramatic, cheap, and fun. From Robert Kramp's Science Education Co.
|
|
Online, via email or through the regular mail. College, accredited high school, free reading and phonics courses, foreign language, history, religion, and more.
|
Arabic, German, Japanese, Spanish, French, Italian, Latin, Russian. Games, free software downloads, free online lessons, newspapers, discussion groups, articles, history, culture, quizzes.
|
Coloring books for kids and adults. Civil war, plants, animals, states, middle ages, cultures, geometric designs, puzzles.
|
Fun and affordable space items for kids, including toys, games, food products, and more.
|
New and used low cost books and textbooks. Websites with open source books and loan programs.
|
|
Artists, wars, armour, castle games, recipes, geography, quizzes, fashions, pictures of weapons, music, old world maps, women of medieval times, medicine, language, and more.
|
Reading systems, loan programs, flashcard, worksheet and test makers, game creators, board games, percentage calculator, puzzle creator, timeline template.
|
SAT, GED, ACT, practice tests, exam preparation. Standardized test practice, content standards listed by state, sample items, scope and sequence, aptitude, essential skills.
|
Parts of speech, civil rights, medieval, periodic table of elements, music, astronomy, world maps with flags, literature, poetry, biology,
|
Books, posters, videos, software, curriculum, courses. Save on teaching supplies, receive free educational materials.
|
|
|
