I II III IV

The Mole

I. Molar Conversions

A. What is the Mole?

A counting number (like a dozen)

Avogadro’s number

1 mol = 6.02 1023 items

A large amount!!!!

1 mole of hockey pucks would equal the mass of the moon!

A. What is the Mole?

1 mole of pennies would cover the Earth 1/4 mile deep!

1 mole of basketballs would fill a bag the size of the earth!

B. Molar Mass

Mass of 1 mole of an element or compound.

Atomic mass tells the... atomic mass units per atom (amu) grams per mole (g/mol)

B. Molar Mass Examples

carbon

aluminum

zinc

12.01 g/mol

26.98 g/mol

65.39 g/mol

• Use Four Sig Figs

B. Molar Mass Examples

water

sodium chloride

H2O

2(1.008) + 16.00 = 18.02 g/mol

NaCl 22.99 + 35.45 = 58.44 g/mol

B. Molar Mass Examples

sodium bicarbonate

sucrose

NaHCO3

22.99 + 1.01 + 12.01 + 3(16.00)

= 84.01 g/mol

C12H22O11

12(12.01) + 22(1.01) + 11(16.00)

= 342.34 g/mol

C. Molar Conversions

molar mass

(g/mol)

MASS

IN

GRAMS

MOLESNUMBER

OF

PARTICLES(atoms, molecules or

formula units)

6.02 1023

(particles/mol)

C. Molar Conversion Examples How many moles of carbon are

in 26 g of carbon?

26 g C 1 mol C

12.01 g C= 2.2 mol C

C. Molar Conversion Examples How many molecules are in

2.50 moles of C12H22O11?

2.50 mol6.02 1023

molecules

1 mol= 1.51 1024

molecules C12H22O11

C. Molar Conversion Examples Find the mass of 2.1 1024

molecules of NaHCO3.

2.1 1024

molecules 1 mol

6.02 1023

molecules

= 290 g NaHCO3

84.01 g

1 mol

C. Molar Conversion Examples Find the mass of 1.00 Fe atom

1 mole Fe = 55.85g 1 mole Fe = 6.02 x 1023 atom 1.00 atom Fe 55.85 g

6.02 x 1023 atoms

= 9.28 x 10-23 g/atom

1 mole

1 mole

C. Molar Conversions How many Oxygen atoms are there in 50.25 g of

CaCO3?

50.25g CaCO3 1 mol CaCO3

100.09 g

3 mol O

1 mol CaCO3

6.02 x 1023atoms O

1 mol O

= 9.075 x 1023 atoms

I II III IV

The Mole-Volume Relationship

The Volume of a Gas

Many of the chemicals we deal with are gases They are difficult to mass

Two things effect the volume of a gas Temperature and pressure

We need to compare gases at the same temperature and pressure

Standard Temperature and Pressure (STP) 0°C and 1 atmosphere (atm) of

pressure At STP, 1 mole of any gas occupies

22.4 L

Called the molar volume

1 mole = 22.4 L of any gas at STP

Practice examples

What is the volume of 4.59 mole of CO2 gas at STP?

How many moles is 5.67 L of O2 at STP?

What is the volume of 8.8 g of CH4 gas at STP?

Molarity –Molar Volume of… Solutions!

Molarity = moles of solute/liter of solution M= n/V

n = moles of soluteV = volume (L) of solution

Note: it’s liters of solution, not liters of solvent

Molarity Examples

How many moles of NaCl are in 0.65 L of 1.20 M NaCl solution?

How many moles of HCl are there in 2.43 L of 0.25 M HCl (aq)?

Molarity Examples

How many grams of HF are there in 0.55 L of 1.5 M HF solution?

How many grams of HNO3 are there in 2.5 L of 5.0 M HNO3 (aq)?

Molarity Examples

Calculate the molarity of a solution made by dissolving 23.4 g of sodium sulfate in 125 ml of solution

23.4 g Na2SO4 0.165 mol 125 ml 0.125 L M = mol / L M = 0.165mol / 0.125 L 1.32 M

Molarity Examples

Calculate the molarity of a solution made by dissolving 5.00 g of C6H12O6 in enough water to make 100.0 ml of solution

0.280 M

Molarity Examples

How many grams of Na2SO4 are required to make 0.350 L of a 0.500 M solution of Na2SO4?

24.9 g Na2SO4