Chemistry 20

Mole Conversions

What is a Mole?

• A term of measurement• A counting number–Similar to saying 1 dozen = 12 things

• Avogadro's Number (NA)

6.02 x 1023 items

A VERY LARGE NUMBER!!!

= 1 mole

• 3.00 moles of little green peas would cover 250 planets the size of Earth 1m deep in green peas

• 1.00 mole of basketballs would fill a bag the size of the Earth

Mole Conversions

Mass In

Grams

Moles

Molar Mass

g/mol

Molar Mass• Molar mass is the mass of one mole in an

element or compound• Atomic mass tells us that the units are

grams per mole g/molExamples:Carbon, C = 12.01 g/molPhosphorus, P = 30.97 g/mol

Molar Mass ExamplesWhat is the Molar Mass of:Salt, NaCl:Na = 22.99g/mol Cl = 35.45g/mol NaCl = 22.99g/mol + 35.45g/mol = 58.44g/mol

Glucose, C6H12O6:C6 = 6(12.01g/mol) H12 = 12(1.01g/mol) O6 = 6(16.00g/mol)

C6H12O6 = 6(12.01g/mol) +12(1.01g/mol) 6(16.00g/mol)

= 180.18 g/mol

Sodium bicarbonate, NaHCO3:

Na= 22.99g/mol H=1.01g/molC=12.01g/molO = 3(16.00g/mol)

NaHCO3= 22.99g/mol + 1.01g/mol + 12.01g/mol + 3(16.00g/mol)

= 84.01g/mol

Mole Conversion ExamplesA grade eleven chemistry student has 3.00 g of boron tribromide (BBr3). How many moles of BBr3 is this?

Molar mass of BBr3 = 10.81 + 3(79.90) = 250.51g/mol

3.00g BBr3 x 1mole = 0.0120 mole BBr3

250.51g

REMEMBER SIG FIGS!

If I have 50.0g of calcium chlorate (CaClO3)2 how many moles do I have?

Molar Mass (CaClO3)2 =

2(40.08) + 2(35.45) + 6(16.00) = 247.06 g/mol

50.0g (CaClO3)2 x 1 mole = 0.202 mole (CaClO3)2

247.06g

Sig Figs

Determine the mass of the following amount:

6.94 mol barium chloride (BaCl2)

Molar Mass BaCl2 = 137.33 + 2(35.45) = 208.23 g/mol

6.94 mol BaCl2 x 208.23 g = 1.45 x 103 g BaCl2

1 mole

Remember only 3 sig figs

Chemistry 20

Mole Conversions

Mole Conversions

RespectiveParticles

Moles

Avogadro’s Number

6.02 x 1023 molecules or

atoms or formula units

Mole Conversion ExamplesIf a chemist is experimenting with 5 700 000 000 atoms of lead how many moles is she dealing with?

Avogadro’s number = 6.02 x 1023 atoms

5 700 000 000 atoms Pb x 1 mole = 9.5 x 10-15 mol

6.02 x 1023 atoms

2 sig figs 2 sig figs

How many moles is in 2.97 x 1025 atoms of Vanadium?

2.97 x 1025 atoms of V x 1 mole

6.02 x 1023 atoms= 49.3 moles of V

Determine the number of molecules in the following:a) 1.01 moles of bismuth

1.01 mol Bi x 6.02 x 1023 atoms

1 mole= 6.08 x 1023 atoms of Bi

b) 2.5 moles of manganese

2.5 mol Mn x 6.02 x 1023 atoms

1 mole

= 1.5 x 1024 atoms of Mn

If the students in a chemistry 20 class have 7.66 x 1019 molecules of hydrogen peroxide, H2O2, how many moles do they have?

7.66 x 1019 molecules x 1 mole

6.02 x 1023 molecules

= 1.27 x 10-4 molecules of H2O2

Chemistry 20

Mole Conversions

Mole Conversions

Volume Moles

Litres of Gas at STP

22.4 L

Mole Conversion ExamplesDetermine the volume, in liters, occupied by 0.030 moles of helium gas at STP.

0.030 moles He(g) x 22.4L = 0.67 L of He(g)

1 mole

REMEMBER UNITS

What is the volume of 0.05 mol of neon gas at STP?

0.05 mol Ne x 22.4L = 1.12L of Ne(g)

1 mole

How many moles of argon atoms are present in 11.2 L of argon gas at STP?

11.2L Ar(g) x 1 mole = 0.5 mole Ar(g)

22.4L

What is the volume of 1.2 moles of water vapor at STP?

1.2 mol H2O(g) x 22.4L= 26.88L of H2O

1 mole

Chemistry 20

Mole Conversions

Mole ConversionsRepresentative

ParticlesVolume at STP

MOLE

Mass

x 1 mole 22.4L

X 22.4L1 mole

x molar mass1mole

x 1mole molar mass

x 1 mole 6.02 x 1023 particles

x 6.02 x 1023 particles1 mole

Mixed Mole Conversion1. Write down the question’s the given

and the unknown.2. Convert the given unit to number of

moles.3. Convert the number of moles found to

the unknown unit.4. Make sure the answer has the correct

unit and number of sig figs.

Mole Conversion ExamplesCalculate the mass, in grams (g), of the following:a) 3.00L of O2(g)

3.00L of O2(g) x 1 mole x 32.00 g = 4.29 g O2(g)

22.4L 1moleb) 15 atoms of gold15 atoms Au(s) x 1 mole x 196.97g = 4.9 x 10-21 g Au

6.02 x 1023 atoms 1 mole

Calculate the number of atoms in 2.0L of SO3 gas.

2.0L SO3(g) x 1 mole x 6.02 x 1023 atoms = 5.3 x 1022 atoms SO3

22.4 L 1 mole

If the students in a Chemistry 20 class have 3.25 x 105 molecules of CO2(g), how many litres do they have?

3.25 x 105molecules of CO2(g) x 1 mole = 5.40 x 10-29 mole

6.02 x 1023 molecules

5.40 x 10-29 mole CO2 x 22.4L = 1.21 x 10-17 L CO2

1 mole