MEET THE MOLE

The Mole

• Avogadro's hypothesis suggests that we can compare the number of molecules in a gas sample.

Even though we can’t see them.• A standard number of molecules is

called a mole (mol). A mole always contains the same number

of molecules. A mole is 6.02 x 1023

A mole of CO2 contains the same number of molecules as O2molecules

Molar Mass

The # of molecules in a mole maybe the same, but the mass will be different.

This is called a molar mass. Molar is based on the mass of Carbon-12. Mass recorded on the Periodic Table takes

into account all of the naturally occurring isotopes of the atom and their relative abundance.

Has units of g/mole

What does the mole allow us to do? The mole allows for the measurement of

really small particles. 1 mole = 6.02 x 1023 (Avogadro’s

Number) The mole takes into account: # of

atoms in a chemical formula, mass of an individual atom, mass of a chemical compound, and # of molecules in a compound

Determine the number of atoms in the following chemical formula Ex. CaCl2 = 1 Ca atom, 2 Cl atoms NaCl KMnO4

H2SO4 Fe2O3

KNO3 K2SO3

C2H6 Al2(SO4)3

Ba(OH)2 HgCl2 NH4Br Mg(C2H3O2)2

Cu(NO3)2 NaC2H3O2

Calculate the mass of each of the following compounds Ex. KCl 39.10 g/mol + 35.45 g/mol = 74.55 g/mol NaCl KMnO4

H2SO4 Fe2O3

KNO3 K2SO3

Al2(SO4)3 Ba(OH)2

NH4Br Mg(C2H3O2)2

Cu(NO3)2 NaC2H3O2

Calculate the moles in each compound How many moles in 60 grams of NaCl? How many moles in 100 grams of H2SO4? How many moles in 60 grams of C2H6? How many moles in 60 grams of

Mg(C2H3O2)2? How many moles in 60 grams of

Al2(SO4)3 ? How many moles in 60 grams of NH4Br ?

Avogadro’s # put to work…

Avogadro’s # (1 mole = 6.02 x 1023 ) is used to convert between moles of a substance and the number of molecules, atoms, particles.

One can also convert between mass of a substance and number of molecules, atoms, particles. Convert mass to moles first

Calculate the # of molecules in each compound How many molecules in 3 moles of Fe2O3?

How many moles in 9.03 x 1023 atoms of Hg?

How many molecules in 5 moles of NH4Br?

  How many moles in 3.01 x 1023 atoms of

HgCl2 ?

Now for some practice…

Calculate the molar mass of oxygen

Now for some practice…

How many dozen are 60 eggs? How many eggs are in 13 dozen? What is the mass of 2.50 moles of

oxygen? How many moles are in 4.00 g oxygen? What is the mass of 2.50 mol carbon

dioxide? How many moles are in 4.00 g carbon

dioxide?