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- Make a similar graph from one of your experiments with a different
size (volume) container.
- How does this graph compare to your first graph?
What are the similarities and what are the differences
?
- Check with other students and compare your graphs.
-
Use your graph line to figure out the corresponding
pressures.
Now do the reverse. Here are some values for
pressure. What are the corresponding
temperatures?
Return to your data table to see if we can discover any
additional patterns from the numbers.
- Multiply T x P for all the pairs of numbers in your data table. Do
you see any consistent
answer?
Check with other students and see if they are getting any pattern with
the product of the numbers.
- Now try dividing P by T. What did you
find?
- Are other students getting the same constant or a different
one?
So if all values of P/T are the same (at a constant volume) then we can
write the following equation (Gay-Lussac's Law):
Where P1 and T1 represent the first set of conditions of our gas and
P2 and T2 represent any second set of conditions.
-
With this equation you should be able to do the
following problem:
If water vapor (gaseous form of water) in a
pressure cooker (constant
volume) is initially at 293 K and 700 mm Hg,
what will be the pressure
if the water vapor is heated to 413 K?
Use Gay-Lussac's Law to calculate the answer.
Before you start, try to decide if the
new pressure will be higher or lower than
700 mm Hg.
-
Now that you have investigated the
relationship between the pressure of a
gas and the temperature of a gas,
you should be able to explain some of the
following:
- Why is a warning placed on all spray cans stating: "do not
incinerate can even if empty, and always store below 120 degrees
F?"
- When you examine the tires on your
bicycle before you start out in
the morning, they appear slightly soft. However, after riding for
several hours, they get harder.
- Why is the freshness button on your pickle jar down
when you buy your pickles?
-
Joseph Gay-Lussac
was a French scientist who worked for years in the early 1800's
to understand how Ideal Gases worked.
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