The Mole

What is a mole?

A mole is a QUANTITY of whatever you are measuring…

1 mole = 6.02 x 1023 of whatever you are measuring

Just like 1 dozen = 12 of whatever you are measuring

Or a couple of things = 2 things

What is a mole?In chemistry a mole measures the number of atoms or molecules

1 mole = 6.02 x 1023 atoms or molecules

Why? 6.02 x 1023 is the number of carbon atoms in 12.01 grams of Carbon

6.02 x 1023 is also known as AVAGADRO’S NUMBER

How Big Is a Mole?The volume occupied by one mole of softballs

would be about the size of the Earth.

How many… dollars would you have if you have 2 moles of dollars?

We would find this out by converting from moles to dollars using Avogadro's number

We do this by doing a unit conversion

Unit Conversion Set Up1. Write down your starting amount2. Write down your conversion factor

(__ starting amount = ___ ending amount)• make sure that your units cancel out

3. Complete the multiplication or division problem to find

the end amount

Converting from moles things

# of moles x 6.02 x 1023 things = # of things 1 mole

How many dollars would you have if you have 2 moles of dollars?

2 moles x 6.02 x 1023 dollars = 1.2 x 1024 dollars 1 mole

More ExamplesHow many atoms of water would you have if you have 3 moles of water?

How many atoms of Helium would you have if you have 5 moles of Helium?

Converting from things moles

# of things x _____1 mole ___ = # of moles 6.02 x 1023 things

It would take 2,103,674,750 pennies to circle the earth, how many moles is this?

2,103,674,750 pennies x ___1 mole _ = 3.49 × 10-15 moles 6.02 x 1023 pennies

More Examples

If you have 9,000,000 atoms of water how many moles of water would you have?

If you have 7,500,000 atoms of Helium how many moles of Helium would you have?

SIMPLEGRAM – MOLE CONVERSIONS

Review

1 mole = 6.02 x 1023 “things”

In chemistry those “things” are particles like atoms and molecules

When converting between atoms and moles it doesn’t matter what the type of molecules or atoms are.• The conversion is the same whether you are

converting Water, Sodium, or any other element/molecule

TodayWe are going to learn two more conversions:• Grams to moles• Moles to grams

When converting between grams and moles you need to look at WHAT you are converting.• The atomic mass of the element is your

conversion factor• The atomic mass of an element is the number of

grams of that element in 1 mole

Converting between grams and moles

Grams to moles: DIVIDE by mass of element# of grams x ___1 mole ___ = # of moles

atomic mass

Moles to grams: MULTIPLY by mass of element# of moles x atomic mass = # of grams

1 mole

Where do you find the atomic mass of an element?

Grams Moles ExamplesYou have 20 grams of Helium, how many moles do you have?

20 grams x ___1 mole ___ = 5 moles of Helium 4.00 grams

You have 50 grams of Oxygen, how many moles do you have?

Moles Grams ExamplesYou have 3 moles of Chlorine, how many grams of chlorine do you have?

3 moles x 35.45 grams = 106.45 grams 1 mole

You have 4 moles of Lithium, how many grams do you have?

ADVANCED GRAM – MOLE CONVERSIONS

Molar Mass

When you are converting between grams and moles for a molecule (example – H2O) you need to use the molar mass to convert

The molar mass is the atomic mass of each element in the molecule added up

Calculating Molar MassCalculating Molar Mass of H2O:

H: 1.008 x 2 There are 2 Hydrogen’s so you= 2.016 have to multiply the weight of

Hydrogen by 2O: 16.00

2.016 + 16 = 18.016 grams

Another example…

Calculate the molar mass of KMnO4 (#1 on WS)

K = Mn = O =

Calculating Molar Mass with Parenthesis

What is the molar mass of Ca(NO3)2? (#4 on WS)

• Number outside the () gets multiplied to everything inside the ()

Ca = N = O =