CHEMICAL QUANTITIES All Roads Lead to the Mole Chemical Quantities Measuring donuts: 1 dozen = 12...

CHEMICAL QUANTITIES

All Roads Lead to the Mole

Chemical Quantities

Measuring donuts:• 1 dozen = 12 donuts (count) • 1 dozen = 500 g donuts (mass)• 1 dozen = 1 box donuts

(volume)Measuring steam (H2O gas):

• 1 mole = 6.02 x 1023 H2O molecules (count)

• 1 mole = 18.0 g H2O (mass)

• 1 mole = 22.4 L H2O (volume) at STP

Dozen: Baker as Mole: Chemist

Count Amedeo Avogadro

• 1776-1856• Lawyer who became interested in

math and physics• Discovered that equal volumes

of different gases contained an equal number of particles.

• 9 years after his death, Joseph Loschmidt determined a constant and named it after Avogadro.

AVOGADRO’S CONSTANT= 6.02 x 1023

Not to be confused with the delicious

fruit

AVOGADRO’S CONSTANT= 6.02 x 1023

• 1 mole = 6.02 x 1023 particles• 1 mole = molar mass (grams)• 1 mole (of a gas at STP) = 22.4 L

The mole is to chemists

as

the dozen is to bakers.

Believe it or not, students all over the country celebrate National Mole Day!

National Mole Day Foundation, INC.

Mole Day

5 Pound Bag of Sugar contains 6.6 moles Of C12H22O11 1 Liter bottle of Water contains 55.5 moles H206.02 x 1023 Grains of Sand: Would be more than all of the sand on Miami Beach.6.02 x 1023 Blood Cells: Would be more than the total number of blood cells found in every human on earth. 6.02 x 1023 Watermelon Seeds: Would be found inside a melon slightly larger than the moon.6.02 x 1023 Pennies: Would make at least 7 stacks that would reach the moon.6.02 x 1023 Donut Holes: Would cover the earth and be 5 miles (8 km) deep.

MassVolume

R.P.Molecules

Atoms

Formula Units

Ions

Draw on NOTETAKERS (and pass out flow Mole Map)

Types of Representative Particles

• Molecules (break down into atoms)

• Atoms

• Formula Units (break down into ions)

• Ions

Naming Representative Particles

Examples: Name the representative particle for each substance given. For each molecule, state how many atoms are present. For each formula unit, state how many ions make up the ionic compound.

H+:

Cl2:

C2H6:

Cu(NO3)2:

Al:

NaCl:

ION

MOLECULE – 2 ATOMS per molecule

MOLECULE – 8 ATOMS

FORMULA UNIT – 3 IONS per Form.U.

ATOM

FORMULA UNIT – 2 IONS per Form.U.

WS: Representative Particles

Do WS #1-20

Mole R.P. Calculations

1 mole = Avogadro’s Number = 6.02 x 1023 R.P.’s

R.P.mol 1

R.P.106.02 23

R.P.106.02

mol 123

R.P. Example 1:How many moles are in 1.4 x 1022 molecules of H2O?

O Hmolecules1002.6

O Hmol 1O Hmolecules104.1

223

2222

OH mol 023.0 2

R.P. Example 2:How many representative particles are in 2.6 mol CO2?

2

223

2

CO mol 1

CO molecules 106.02CO mol 6.2

224 CO molecules 106.1

R.P. Example 3:How many atoms are in 5.2 mol CO2?

22

223

2

CO molecule 1

atoms3

CO mol 1

CO molecules106.02CO mol 2.5

atoms104.9 24

DO WS:

The Mole and Avogadro’s Number

MOLAR MASS

The molar mass is the mass, in grams,

of one mole (6.02 1023 particles) of an

element (ion), a covalent molecule or a

formula unit.

molar mass (MM) gram atomic mass (gam)molecular weight (MW) gram molecular mass (gmm)formula mass (FM) gram formula mass (gfm)formual weight (FW)

Molar Mass … a.k.a. Molecular Weight (MW)

molar mass = mass of 1 mole of substance

Molar mass can be determined by adding up the atomic masses from the periodic table (atomic mass goes to 2 decimal places).

MW Example 1:

Find the MW of CH4.

= 1C + 4H = 12.01 + 4(1.01) = 16.05 g CH4/mol CH4

MW Example 2:

Find the MW of Mg(OH)2.

=Mg + 2O + 2H=24.31 + 2(16.00) + 2(1.01)=58.33 g Mg(OH)2 /mol Mg(OH)2

MW Example 3:

Find the MW of MgSO4∙7H2O.

=Mg + S + 4O + 7(H2O)

=24.31 + 32.07 + 4(16.00) + 7(1.01+1.01+16.00)

= 246.52 g MgSO4∙7H2O /mol MgSO4∙7H2O

Calculations:

Use Mole Map to help calculate

Mole Mass Calculations

1 mole = molar mass (MW) in grams

Massmol 1

(g) massmolar

(g) massmolar

mol 1

Mass Example 1:

How many grams are in 7.20 moles of dinitrogen trioxide?

MW of N2O3 = 2N + 3O = 2(14.01) + 3(16.00) =76.02 g/mol

1 mole = 76.02 g N2O3

dinitrogen trioxide = N2O3

3232

3232 ON g547ON mol 1.00

ON g 02.76ON mol20.7

Mass Example 2:

Find the number of moles in 92.2 g of iron(III) oxide.

MW of Fe2O3 = 2Fe + 3O = 2(55.85) + 3(16.00) =159.70 g/mol

1 mole = 159.70 g Fe2O3

iron(III) oxide = Fe2O3

3232

3232 O Femol577.0O Feg 159.70

O Femol 1O Feg2.92

Practice Worksheet

Do #1-10 on Mole and Mass WS

Make sure you write out all work and include all units!!

Mole Volume Calculations

1 mole = 22.4 L of gas at STP

STP = standard temperature and pressure (0 °C & 1 atm)

Volumemol 1

L 22.4

L 22.4

mol 1

Volume Example 1:

Determine the volume, in liters, of 0.600 mol of SO2 gas at STP.

2

22

SO mol 1

SO L4.22SO mol600.0

2SO L4.13

Volume Example 2:

Determine the number of moles in 33.6 L of He gas at STP.

He L22.4

Hemol 1 He L3.63

He mol 50.1

Density

density = mass / Volume

When given the density of an unknown gas, one can multiply by the molar volume to find the MW.

The MW can allow for identification of the gas from a list of possibilities.

Density Example (part A):

The density of an unknown gas is 2.054 g/L at STP. (a) What is the molar mass?

massmolar memolar voludensity

1mol

L4.22

L

2.054g g/mol 01.46

Density Example (part B):

The density of an unknown gas is 2.054 g/L. (b) Identify the gas as either nitrogen, fluorine, nitrogen dioxide, carbon dioxide, or ammonia.

MW = 46.01 g/mol (from part a)

Nitrogen = N2 = 2(14.01) = 28.02 g/mol

Fluorine = F2 = 2(19.00) = 38.00 g/mol

Nitrogen dioxide = NO2 = 14.01 + 2(16.00) = 46.01 g/mol

Carbon dioxide = CO2 = 12.01 + 2(16.00) = 44.01 g/mol

Ammonia = NH3 = 14.01 + 3(1.01) = 17.04 g/mol

Mixed Mole Conversions

1 mole = 6.02 x 1023 RP’s =

MW = 22.4 L of gas @STP

All Roads Lead to the Mole.

Always convert to units of moles first when converting between grams, liters, and representative particles.

Mixed Mole Example 2:

How many atoms are in 22.0 g of water?

242.20 10 atoms

22.0  g H 2O❑ ×

1  mole   H 2O18.02  g  H2 O

×6.02 ×10 23  molec .  H2O1  mole  H 2O

×3  atoms1 molec .  H2O

Mixed Mole Example 1:

How many carbon atoms are in a 50.0-carat diamond that is pure carbon? Fifty carats is the same as 10.0 g.

C mol 1

C atoms 1002.6

C g 12.01

C mol 1C g 0.10 23

C atoms 1001.5 23

Extra questions to review concepts

What is the mass of 3.7 moles of NaCl?

a) 15.8 gb) 58.5 gc) 220 gd) 6.02 x 1023 g

NaCl mol 1

NaCl g 44.58NaCl mol7.3

NaCl g 23.216

How many moles are in 152 g of water?

a) 0.118 molb) 8.44 molc) 2736 mold) 6.02 x 1023 mol

O Hg 02.18

O Hmol 1

1

O Hg 152

2

22

O Hmol 44.8 2