Dimensional Analysis – mole and number of particles

Dr. Chin Chu

Alternative Counting Units

1 pair = 2

1 dozen = 12

Alternative Counting Units

1 baker’s dozen = 13

1 US bushel ≈ 35.2 L

http://www.unc.edu/~rowlett/units/scales/bushels.html

Alternative Counting Units

1 fluid barrel ≈ 119.2 L

Alternative Counting Unit for Chemistry

As the size of the particles decreases, number of

particles increases to get a sample that is tangible.

http://htwins.net/scale2/?bordercolor=white

THE MOLE

The mole concept is no different from other

alternative counting units.

1 mole (A) = 6.022 x1023 particles of (A)

6.022 x 1023 particles (A)

1 mole (A) = 1

6.022 x 1023

particles (A)

1 mole (A) = 1

The number is so big is due to the extremely small sizes

of molecules, ions and atoms.

• One mole of paper would make a stack that would reach to the moon more than 80 billion times.

• One mole of grains of sand would be more than all of the sand on Miami Beach.

• One mole of blood cells would be more than the total number of blood cells found in every human on earth.

• A one liter bottle of water contains 55.5 moles of water.• There are 3 types of moles that live underground in North America:

Eastern Mole, Hairy-Tailed Mole and Star-Nosed Mole.• One mole of inches would be1,616,434 light years, or across our galaxy

and back 8 times.• One mole of seconds is about 19 quadrillion years, 4,240,666 times

the age of the earth, or 954,150 times the age of the universe itself!• One mole of cents could repay the United States National Debt 86 million

times.

Amazing Mole Facts:

6.022 x 1023 molecules

(H2)1 mole (H2)

MOLE-PARTICLES EXAMPLE 1

Finish the math.

0.456 mol. (H2) =

= 2.75 x 1023 molecules (H2)

Bravo! Mission accomplished.

Q - How many hydrogen molecules are there in 0.456 moles of hydrogen gas?

0.456 mol. (H2) x

If you are really good at this, an equivalent but

simpler protocol could be used.

THE MONKEY BAR:

0.456 mol. (H2) =0.456 mol. (H2)

mole (H2)

= 2.75 x 1023 molecules (H2)

6.022 x 1023molecules

(H2)

1

MOLE-PARTICLES EXAMPLE 1

molecules (H2O)

Use the factor-labeling approach. Let the units

guide the math.

7.83x1024 molecules (H2O)

mole (H2O)

= 1.30 x 101 molecules (H2O)

6.022 x 1023

1

MOLE-PARTICLES EXAMPLE 2Q - How many moles of water in 7.83 x 1024 molecules

of water?

7.83x1024 molecules (H2O)=

The End