Student Name: ____________________
Date: ____________________
What is Rust? (part 1)
There are two things that are very important in determining how fast and how severely a
metal object rusts. The first is what type of metal it is made from, and the second is what
type of environment it is in. Using the metal samples and solutions available, choose
three experiments to do in order to test the role of metal type or environment.
Type of
Metal
Solution
Observations
at Beginning
of Experiment
What is Rust?
-1–
Observations
After 1 Day
Observations
After 1 Week
Student Name: ____________________
Date: ____________________
What is Rust? (part 2)
Now that you have observed your nails in various solutions
over the past week, you have seen that different types of
chemical reactions take place in different environments.
So, why do certain environments lead to faster corrosion, or
rust?
As you may know, all materials are made from elements;
steel is mostly made from the element iron (Fe). Elements
are able to have different charges. For example, Iron can be
neutral or have a charge of +2 or +3. The properties that we
associate with metals like steel, like shininess, strength and
moldability, come from elements with neutral charges.
Rusting happens when the charge changes from a neutral charge to a positive charge.
This happens when the metal gives up electrons to its
environment (remember electrons carry a negative charge).
Fe0 →Fe+2 + 2 electrons
Certain solutions make it easier for metals to lose their
electrons. What type of solutions do you think these might be?
Why?
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As you may have noticed, both acidic solutions and salt solutions lead to
corrosion even though the products have different appearances. This is
because they are able to transfer electrons easily.
What does it really mean to be an “acidic” solution? One definition states
that “acidic” things taste sour and non-acidic, or “basic” things taste bitter.
Without tasting, another way to test the acidity of a solution is to use “pH” paper. This
method uses numbers to indicate the acidity of a substance. Solutions that measure 0-7
are acids and solutions that measure 7-14 are basic.
What is Rust?
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In the chart below, make a prediction about the following substances. Then test each
substance using the pH paper:
Test Solution
Windex
pH prediction
pH test results
Acid/base?
Water
Apple Juice
Orange Juice
Shampoo
Coke
Lime Juice
Vinegar
Baking soda
solution
Using what you know about the corrosive effect of acid on metals, would you make a
Coke can out of steel? Why or why not? ___________________________________
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Why do you think soda cans are made from aluminum? ______________________
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Pollution causes rain to be acidic – “acid rain.” How do you think that acid rain effects
metal structures like bridges and buildings? ________________________________
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What is Rust?
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