The Mole

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					                 The Mole Packet
A mole is basically just a word for a number. In the same way we say one "hundred" meaning
100, or one "million" meaning one 1,000,000, we could also say one "mole" which also
corresponds to a number. A mole is a very larger number indeed. In numbers, it would be
written as 602213670000000000000000. Thus you can see why people refer to them as "moles"
rather than writing out the entire number.

Theoretically, you can have a mole of anything you want. A mole of apples, a mole of oranges,
or whatever. But because the number is so very large, it tends to only apply to things that there
are a lot of. For example, the number of grains of sand in a beach several miles long might be a
mole or two. The number of leaves in a large forest might be a few moles. Usually, however,
the mole is used in connection with atoms.

Different elements of the periodic table weigh different amounts. One atom of sodium, for
example, is considerably lighter than one atom of chlorine. Suppose we wanted to combine
sodium and chlorine to form table salt (sodium chloride). If we mix up 10 grams of sodium with
10 grams of chlorine, we will have large amounts of sodium leftover. This is because a chlorine
atom is about one and a half times heavier than a sodium atom. Ten grams of sodium weighs
the same as ten grams of chlorine, but there are more sodium atoms present than chlorine atoms,
since chlorine atoms weigh more. (If I give you 10 pounds of bricks, you will not expect many
bricks . . . but if I give you 10 pounds of feathers, that will be a lot of feathers).

In order to relate things in equal quantities, we need to have the same number of atoms, not the
same weight. Ten atoms of sodium--no matter what they weigh--will react perfectly with ten
atoms of chlorine, leaving us with no leftovers. But an atom is so incredibly tiny that even our
most microscopic equipment could not hope to measure out ten atoms of anything. So instead,
we work in moles of atoms. An atom is a very very tiny thing, but a mole of atoms
(602213670000000000000000 atoms) is something large enough for us to see and work with
easily. A mole of carbon atoms, for example, weighs about 12 grams. A mole of sodium atoms
weighs about 23 grams. A mole of chlorine atoms weighs about 35.5 grams, and so on. By
working in "moles of atoms" (abbreviated to just "moles") we are working on a scale that
involves reasonable numbers.


                          For ALL Practice Problems:
                                   show ALL your work
                                   use factor-label method where applicable
                                   use units with your calculations and with your final answer
                                   CIRCLE your final answer
                                   Pay Attention to SIG FIGS
                                   Use Scientific Notation where applicable
                          One Mole is A Lot of Things
                                       modified from Dave Tanis
When working with the mole concept, students often have trouble comprehending the enormous
size of Avogadro's number, 6.02 x 1023. The following analogies may be helpful for students.

    If there were a mole of rice grains, all the land area in the whole world would be covered
     with rice to a depth of about 75 meters.
    One mole of rice grains is more grains than all the grain that has been grown since the
     beginning of time. (1)
    One mole of rice would occupy a cube about 120 miles on an edge! (1)
    A mole of marshmallows would cover the United States to a depth of 600 miles (3)
    In order to put a mole of rain drops in a 30 meter (about 100 feet) diameter tank, the sides
     of the tank would have to be 280 times the distance from the Earth to the Sun. (4)
    A mole of hockey pucks would be equal to the mass of the Moon.
    Assuming that each human being has 60 trillion body cells (6.0 x 1013) and the Earth's
     population is 6 billion (6 x 109), the total number of living human body cells on the Earth
     at the present time is 3.6 x 1023or a little over half of a mole.
    If one mole of pennies were divided up among the Earth's population, each person would
     receive 1 x 1014 pennies. Personal spending at the rate of one million dollars a day would
     use up each persons wealth in about three thousand years. Life would not be comfortable
     because the surface of the Earth would be covered in copper coins to a depth of at least
     400 meters.
    If you had a mole of pennies and wanted to buy kite string at the rate of a million dollars
     per inch, you would get your money's worth. After stretching your string around the
     Earth one million times, and to the Moon and back twenty-five times, you would have
     enough string left over to sell back at a dollar an inch (a decided loss) to gain enough
     money to buy every man, woman and child in the US a $50,000 automobile and enough
     gasoline to run it at 55 mph for a year. After those purchases, you would still have
     enough money left over to give every man, woman, and child in the whole world about
    The CRAY-1 super computer has a nominal speed rating of 1000 mips (millions of
     instructions per second) and could count the entire population of the US in ¼ second, but
     would still require 1.9 million years to count to Avogadro’s number.
    If you won 1 mole of dollars in a lottery the day you were born, and sent a billion dollars
     a second, you would have more than 99.999% of the prize money left when you died at
     age 90.

     An ordinary 8-ox glass of water contains about 13.1 moles of water, which amounts to
      13.1 Avogadro’s number or just under 7.9 x 1024 molecules of water…………………..
                 (79,000,000,000,000,000,000,000,000 molecules of water!!!!!)
     In terms of chemical particles, an aluminum soft drink can, which weighs about 16.5 g,
      contains about 3.68 x 1023 atoms of aluminum.
     A mole of seconds represents a span of time 5 million times as long as the earth has
      already existed.

     If you started counting when you first learned how to count and then counted by ones,
      eight hours a day, five days a week for 50 weeks a year, you would be judged a ‘good
      counter’ if you could count to about 4 billion by the time you retired on a well earned
      pension at age 65. If all the people now living were to count by ones from the time when
      they first learned to count until they retired at age 65, all of these people together could
      just count all of the atoms of iron in the head of a straight pin! By comparison, it would
      take this same army of counters just 2 months to count all the leaves on all the trees,
      bushes and shrubs in the entire world.

    Think about and write an answer to these questions:

     If you had a mole of water molecules, could you swim in them? Why or why not?

     If you were really thirsty on a hot summer day, would a mole of ice cold water molecules
      quench you thirst? Why or why not?

Basis for calculations:
Earth's circumference = 25,000 miles        Distance to moon = 240,000 miles
Cost of gasoline = $2.50 per gallon         Gasoline mileage = 20 miles per gallon
U.S. population = 220,000,000              World population = 6,000,000,000

(1) Kolb, Doris. "The Mole," J. Chem. Educ., 55:728-32 (1970)
(2) Heikkinan, H. and Atkinson, G., Reactions and Reason, Harper and Row, NY, 1973 ed. p. 69.
(3) Teacher's Guide, S

1. Define the Following:

       a) average relative atomic mass

       b) formula mass

       c) molar mass:

       d) Avogadro’s Number

       e) mole:

2. What is the abbreviation for the mole? ________________________________________________________

3. How many particles are in one mole? _________________________________________________________

4. What is the name given to the number of particles in a mole? ______________________________________

7. How is the mass in grams of an element converted to amount in moles?

8. How is the mass in grams of an element converted to number of atoms?

Example: C6H12O6
                C = 12.01 x 6        = 72.06 amu
                H = 1.01 x 12        = 12.1 amu
                O = 16.00 x 6        = 96.00 amu
                Formula Weight        = 180.16 amu =           180.2 amu
 always round the atomic mass taken from the periodic table to 2 digits past the decimal point

Calculate the formula weight of:
    1. ammonium sulfide: ___________________                           2. iron (III) chloride trihydrate: ____________

Example: C6H12O6
                C = 12.01 x 6        = 72.06 g
                H = 1.01 x 12        = 12.1 g
                O = 16.00 x 6        = 96.00 g
                   Molar Mass         = 180.16 g/ mol =           180.2 g/ mol
       always round the atomic mass taken from the periodic table to 2 digits past the decimal point

1. potassium aluminum sulfate: ______________                      2. barium thiocyanate: _______________________

Practice Problems: MOLECULES-TO-MOLES
Calculate the TOTAL number of MOLES in each of the following:
1) 3.55 x 1020 molecules of elemental bromine         Chemical Formula: _________________

2) 10. Trillion molecules of dihydrogen monoxide      Chemical Formula: _________________

Practice Problems: MOLES-TO-MOLECULES
Calculate the TOTAL number of MOLECULES in each of the following:

1) 1.5   10-2 moles of carbon dioxide: Chemical Formula: ______________________________________

2) 8.3 x 103 moles of nitrogen trihydride: Chemical Formula: __________________________________

Practice Problems: MOLES-TO-UNITS
Calculate the UNITS for each of the following:

1) 1.058 mole of aluminum hydroxide :                 Formula: _______________________________

2) hydroxide ions in 2.5 mole of iron (II) Sulfide:   Formula: ________________________________

                  Practice Problems: UNITS-TO-MOLES
Calculate the MOLES for each of the following:

1) 2.48 x 1022 units of calcium nitrate :             Formula:___________________________

2) 1.9 x 1062 units of copper (II) sulfate            Formula: _____________________________

                Practice Problems: MOLES-TO-MASS
Calculate the MOLES for each of the following:

1) 0.200 moles of dihydrogen monosulfide :       Formula: _________________________________

2) 0.75 moles of potassium iodide :              Formula: _________________________________

                Practice Problems: MASS-TO-MOLES
1) 75.57 grams of potassium bromide :            Formula: ________________________________

2) 0.750 grams of sodium bicarbonate:            Formula: _________________________________

      Practice Problems: MASS-TO- UNITS/ MOLECULES
Calculate the number of UNITS/ MOLECULES in the following:

1) 23.5 grams phosphorous pentachloride:                   Formula: _________________________________

2) 155.5 grams copper (II) sulfate pentahydrate:           Formula: _________________________________

  Practice Problems: UNITS/ MOLECULES-TO-MASS
Calculate the MASS, in grams, for each of the following:

1) 7.5 x 1024 units of sodium chloride:                    Formula: __________________________________

2) 8.4 X 1032 molecules of carbon tetrahydride:            Formula: __________________________________


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