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

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CHEMICAL QUANTITIES All Roads Lead to the Mole

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

Page 1: 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.

CHEMICAL QUANTITIES

All Roads Lead to the Mole

Page 2: 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.

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

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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.

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AVOGADRO’S CONSTANT= 6.02 x 1023

Not to be confused with the delicious

fruit

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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

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The mole is to chemists

as

the dozen is to bakers.

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

National Mole Day Foundation, INC.

Mole Day

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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.

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MassVolume

R.P.Molecules

Atoms

Formula Units

Ions

Draw on NOTETAKERS (and pass out flow Mole Map)

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Types of Representative Particles

• Molecules (break down into atoms)

• Atoms

• Formula Units (break down into ions)

• Ions

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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.

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WS: Representative Particles

Do WS #1-20

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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

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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

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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

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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

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DO WS:

The Mole and Avogadro’s Number

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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)

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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).

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MW Example 1:

Find the MW of CH4.

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

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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

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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

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Calculations:

Use Mole Map to help calculate

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Mole Mass Calculations

1 mole = molar mass (MW) in grams

Massmol 1

(g) massmolar

(g) massmolar

mol 1

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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

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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

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Practice Worksheet

Do #1-10 on Mole and Mass WS

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

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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

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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

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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

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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.

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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

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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

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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.

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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

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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

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Extra questions to review concepts

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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

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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