Download Avogadro`s Number

AVOGADRO’S NUMBER
Amedeo Avagodro
1176 - 1856
Look up into the sky on a clear night. You may be able to see about 3,000 stars with the naked
eye, but the number of stars swirling around you in the known universe is approximately equal
to Avogadro’s number 6.02 x 1023. Just think, the known universe contains approximately a
mole of stars. You don’t have to leave the Earth to encounter such a large number. The water
in the Pacific Ocean has a volume about 6.02 x 1023 milliliters and a mass about 6.02 X 1023
grams.
Avogadro’s number is almost incomprehensibly large. For example if one mole of dollars was
given away at the rate of a million dollars per second beginning when the Earth was first
formed some 4.5 billion years ago, would any remain today? Surprisingly, about three fourths
of the original mole of dollars would be left today; it would take about fourteen billion, five
hundred million more years to give away the remaining money at one million dollars per
second.
The impressively large size of Avogadro’s number can give us very important insights into the
very small size of individual molecules. In a single drop of water there are about 1.7 x 1021
water molecules. There are fewer teaspoons of water in the Atlantic Ocean than there are water
molecules in a teaspoon of water.
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Name ____________________________
AVOGADRO’S NUMBER
Period ____ Date _________ Seat ____
Purpose: During the activity comparisons will be made to facilitate your comprehension of
both the magnitude of Avogadro’s number and the size of molecules, atoms and ions. Data will
be collected and used as conversion factors to solve problems using dimensional analysis.
Materials:
Rice, 100mL beaker, 10 mL graduated cylinder, stop watch, balance, metric ruler
Procedure:
1. Determine the number of seconds one member of your lab group can count 100 rice
grains using a stop watch.
2. Determine the mass of 100 rice grains.
3. Determine the space-filled volume of 100 rice grains using a 10 ml graduated cylinder.
4. Determine the length of 20 rice grains laid end to end in cm.
Conclusion:
1. How many years would it take you to count a mole of rice grains?
2. How many years would it take the population of the Earth to count Avogadro’s
number of rice grains?
3. How many rice grains laid end to end would it take to reach the sun?
4. The nearest star (other than our sun) is Alpha Centauri at 4.367 light years away from the
Earth. How many rice grains laid end to end would it take to reach Alpha Centauri?
5. How many times would a mole of rice grains reach to the sun and back? To Alpha Centauri
and back?
6. How deep, in miles, would Texas be covered if a mole of rice grains were poured on Texas?
7. The annual production of rice is 32,000,000,000,000 Kg. How many years would it
take to grow a mole of rice grains?
8. Assuming man has grown rice for 200,000 years, has there been a mole of rice grown?
USEFUL FACTS AND FIGURES AND IRRELEVANT TID BITS
One light year is 5,865,676,000,000 miles
2.54 cm is an inch
5280 feet are in a mile
A football field is 98.97 meters long
Texas has a surface area of 262,000 miles2
It is 93 million miles to the sun on a clear day at noon
Earth’s population is about 6 billion
MOLE FACT
If a mole of pennies were divided up and given to every person on the earth, each person would
receive 1.5 X 1016 pennies. Personal spending at a rate of one thousand dollars a day would use
up each person’s wealth in just over four thousand years. Life would be comfortable; however,
the surface of the earth would be covered in copper coins to a depth of 420 meters.
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