1 mole = 6.02 X 10 23 things This is called Avogadro’s number

1 mole =

6.02 X 1023

things

This is called Avogadro’s number

Molar massMolar mass is the mass of a mole of that thing

The molar mass of pennies is the mass of 6.02X1023 pennies (about 2X1024 grams)2 million million million tons of pennies

The molar mass of carbon is the mass of 6.02X1023 carbon atoms (which happens to be exactly 12 grams)

Molar massThe molar mass of:

Ca = 40.08 gramsMgCl2 = 95.2 grams

H2O = 18 grams

(using the periodic table)

MolesThere are one mole of:

Atoms in 40.08 grams of Ca (element)Formula units in 95.2 grams of MgCl2 (ionic)

Molecules in 18 grams of H2O (molecular)

Remember that representative particles refer to the types of substances we are measuring

Moles

1 mole of atoms in 40.08 grams of Ca3 moles of atoms in 95.2 grams of MgCl2

3 moles of atoms in 18 grams of H2O

This will come in handy when we study chemical reactions.

MolesGram atomic mass (GAM) refers to the mass of one mole of atoms of an element

Gram molecular mass (GMM) refers to the mass of one mole of molecules of a compound

Gram formula mass (GFM) refers to the mass of one mole of formula units of an ionic compound

6.02 X 1023 remember this number

Name Formula Representative particle Element 1 Element 2 Element 3

Gram atomic mass (GAM)

Strontium Sr atom Sr - - 87.6 g

Iron

Cobalt

Silicon

Aluminum


Gram formula mass

(GFM)

Magnesium sulfate MgSO4 Formula unit Mg S 4 O 123.3 g

Potassium iodide

Calcium sulfite

Lithium oxide

Beryllium fluoride


Gram molecular

mass (GMM)

Carbon tetrachloride CCl4 molecule C Cl - 153.8 g

Carbon monoxide

Silicon dioxide

Nitrogen

Dihydrogen sulfide

How many moles in 26.8 grams of iron?


We are given grams of iron, so that goes on the left

We want moles, so that must end up on the right

Make conversion factors do that


26.8 g Fe mole Fe55.85 g Fe

given Conversion factor



Cancel units in numerator and denominator



.48 mole Fe

We will need to be able to figure out how many grams are in a certain number of moles.

We use the same conversion factor as we just did, only inverted.

How many grams in .48 moles of iron?


.48 mol Fe 55.85 g Femol Fe

given Conversion factor


.48 mol Fe 55.85 g FeMol Fe

Cancel units in numerator and denominator


.48 mol Fe 55.85 g Femol Fe

26.8 g Fe

Conversion factors:12 in / 1 ft

5280 ft / 1 mi

1 mi = 1.61 km

1 ft / 12 in

1 mi / 5280 ft

1.61 km / 1 mi

Conversion factors for calculating moles and grams:

12 g C / mol C Mol C / 12 g C

153.8 g CCl4 / mol CCl4 Mol CCl4 / 153.8 g CCl4

123.3 g MgSO4 / mol MgSO4 Mol MgSO4 / 123.3 g MgSO4

Things we’ll need to be able to do:

• Write chemical formulas from chemical names– Magnesium sulfate is MgSO4

• Calculate molar mass from chemical formulas– 123.3 g MgSO4 is one mole MgSO4

• Use conversion factors to calculate moles from mass, and mass from moles– 123.3 g MgSO4 / mol MgSO4

– mol MgSO4 / 123.3 g MgSO4

How many grams in .06 mole potassium nitrate?


• Formula?


• Formula?

• Molar mass?


• Formula?

• Molar mass?

• Conversion factor?


.06 mol KNO3

101 g KNO3

mol KNO3

6.06 g KNO3

given conversion factor

How many moles in 486 grams aluminum sulfate?

How many moles in 486 grams aluminum sulfite?

• Formula?


• Formula?

• Molar mass?


• Formula?

• Molar mass?



486 g Al2(SO3)3

mol Al2(SO3)3

294 g Al2(SO3)3

1.65 mol Al2(SO3)3


1 mole of any element

6.02 X 1023 atoms of that

element

1 molar mass of that

element

How many molecules in 287 grams carbon dioxide?


• Formula?


• Formula?

• Molar mass?


• Formula?

• Molar mass?



287 g CO2

6.02 X 1023 molecules CO2

44 g CO2

3.93 X1024 molecules CO2


1. How many grams are in 2.73 moles of sodium chloride?

2. How many moles are in 682 grams of strontium nitrate?

3. How many representative particles are in .187 grams of copper(II) sulfate?

4. How many atoms are in 87.1 grams of magnesium chloride?

5. 239 grams of carbon tetrachloride is how many moles of molecules?

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1 mole = 6.02 X 10 23 things This is called Avogadro’s number