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The Mole Concept

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The Mole Concept

infinitesimally

Atoms are so _____________________ small, that

a tiny teaspoon of carbon contains an ____________________large quantity of carbon atoms.

Unimaginably

2.0 x 1022

≈

1 tsp.

charcoal

Carbon Atoms

The time required to count SO MANY particles is _______________long.

impossibly

If the time taken to count 10 atoms was 1 second.

It would take 6.3 x 1013 years to count the amount of carbon atoms on the teaspoon!

It is better therefore to regard particles in groups rather than individual units.

- Chemists count atoms in a bulk unit called the __________.
- A __________ is equivalent to the number of C-12 atoms in exactly 12 grams of C-12.

mole

mole

1 mol C-12 = 6.022 x 1023C-12 atoms

1 mol C-12 = 12 grams C-12

12 grams C-12 = 6.022 x 1023C-12 atoms

Number of items

Bulk Quantity

- 1 dozen donuts
- 1 GrosSof beads
- 1 Score of years

- 12 donuts
- 144 beads
- 20 years

Chemisty BULK Unit is the Mole

Bulk Quantity

Number of items/particles

- 6.022 x 1023Na atoms
- 6.022 x 1023H2O molecules

- 1 molENa atoms
- 1 Mol H2O

Chemisty BULK Unit is the Mole

mol

The unit mole is abbreviated as _________.

In equations, a mole is represented the symbol ____.

n

1 mol of anything =

6.022x 1023of that thing

The number 6.022 x 1023is called ___________________________.

Avogadro’s Number

In equations, a Avogadro’s Number is represented the symbol ____.

NA

A Moleof Various Elements

6.022 x 1023 atoms

6.022 x 1023 atoms

6.022 x 1023 atoms

6.022 x 1023 atoms

6.022 x 1023 atoms

Molar Mass

Average Atomic mass

________________ represents the mass of ______atom in atomic mass units (u)

ONE

22.99

1 Na atom = _________ u.

grams

____________________ is the mass in __________ of a ___________ quantity.

Molar mass

1 Mole

_____________ Na atoms = _______grams.

6.022 x1023

22.99

Average atomic mass (9.01218 u/1 atom)

Molar Mass (9.01218 g/ mol of atoms)

Be

Molar Mass = MASS in grams of 1 mole

Molar Mass = MASS in grams of 1 mole

1 mol “Stuff”= 6.022 x 1023 pieces of “Stuff”

Molar Mass = MASS in grams of 1 mole

1 mole carbon

= 12.01 g

6.022 x 1023 C atoms

= 12.01 g

1 mol “Stuff”= 6.022 x 1023 pieces of “Stuff”

Molar Mass = MASS in grams of 1 mole

1 mole carbon

= 12.01 g

6.022 x 1023 C atoms

= 12.01 g

1 mol “Stuff”= 6.022 x 1023 pieces of “Stuff”

Molar Mass = MASS in grams of 1 mole

1 mole sulfur

= 32.06 g

6.022 x 1023 S atoms

= 32.06 g

Calculating Molar Mass

The molar mass of a substance is represented by the symbol MM (or M).

The unit of molar mass is g/mol.

To find the molar mass of an element, simply read off the atomic mass on the periodic table and use the unit g/mol.

E.g. What is the molar mass of iron?

MMFe = 55.845 g/mol

Calculating Molar Mass of a compound

To do this find the total of the masses of all the elements in the compound.

E.g. What is the molar mass of sodium carbonate (Na2CO3)?

MM = 2(MMNa) + MMC + 3(MMO)

= 2(22.99)+12.011+3(15.999) g/mol

= 105.99 g/mol