Chapter 10 Chemical Quantities

A representative particle (RP) refers to the species present in a substance, usually atoms(S), molecules(SO2), or

formula units(NaCL)

A representative particle (RP) refers to the species present in a

substance, usually

Element: atoms, Covalent Bond: molecules, or

Ionic Bond: formula units

A representative particle (RP) is: 1 atom, 1 molecule,

or 1 formula unit.

3 Word Summary:Representative Particle =

Atoms, Molecules or Ionic Formula

.

How many atoms do you see?

Molecules?

How many atoms do you see?

Molecules?

How many atoms do you see?

Molecules?

How many atoms do you see?

Molecules?

You must state very specifically what the particle

represents: atoms or

molecules and of what?

State what is the RP: An atom of O, An atom of C or a molecule of CO2?

Does this look like air? Does air

have a representative

particle?

Answer is NO! There is not a

particle of air. Air is about 80% N2 and 20% O2.

Air is composed of several

representative particles mixed

together.

So Mixtures do NOT have representative particles.

The mole = mol6.02 x 1023 representative

particles (RP) of a substance is called Avogadro's number.

MEMORIZE:

Mole =

6.02 x 1023

6.02 x 10 23

Emphasis is on 10 23

Why on the 23 and not the 6.02?

1.) If you have $5 x 10 5+/- $1 Does the 1 matter?

2.) If you have $5 x 10 5 +/- 10 1 Does it matter?

Which is more important?

1.) If you have $5 x 105 +/- $1 Does the 1 matter?

This ranges from 400,000 to 600,000

2.) If you have $5 x 10 5 +/- 101 Does the 1 matter?

This ranges from $50,000 to $5 million.

Which is more important?1.) 400,000 to 600,000 or 2.) $50,000 to $5 million

A mole is just a name of a number.

Like Pi = 3.14159265 and e = 2.718

Mole =

6.02 x 1023

A mole is just a name of a number. Like Thousands, Millions, Billions, Trillions, Quadrillions, Gazillionbillions

Mole =

6.02 x 1023

There is a very specific reason that we use a mole,

Atomic Mass in grams is equal to 1 mole of an element.

Do some examples Have students do elements off the periodic table.Shoe 1 mole samples on counter..

Molar Mass = grams of 1 mole of atoms = Atomic Mass

6.02 x 1023

Avogadro discovered the mole, but the exact number was

determine later. So it was named after. So it’s 2nd name is

Avogadro's number

6.02 x 1023

Review Dimensional Analysis.Known x Conversion Factor = Wanted

Known x Wanted = Wanted

KnownExample, convert feet to inches.

4 ft x 12 inches = 48 inches

1 ft .

1.) Do the dimensions or units first.

Cross off feet and inches are left.

2.) Fill in # and multiply and divide the numbers.

How many atoms of sodium are in 2.0 moles?

Na = RP

How many atoms of sodium are in 2.0 moles?

Na = RP

How many atoms of sodium are in 2.0 moles?

Na = RP

Note: Adjust answer for 1.) Scientific Notation2.) Significant Figures

How many carbon atoms are in 3.0 moles of C2S?

1 molecule C2S = 1 RP

How many carbon atoms are in 3.0 moles of C2S?

1 molecule C2S = 1 RP1 RP has 2 C atoms

3 mol of C2S x 2 C atoms = 6 mol C

= 6 mol C x 6.0 x 1023 atoms/mol = 36 x 1023 atoms = 3.6 x 1024 atoms

How many grams of carbon are in 3.0 moles of C2S?

How many grams of carbon are in 3.0 moles of C2S?

3.0 mol C2S = 6.0 mol C

= 6.0 mol C x 12 g/mol C = 72g C

How many pennies is 1 mole

of pennies?

Would it cover the earth?

How deep?

How much is a mole of pennies? A mole of pennies would cover the

entire Earth to a depth of 300 m,

or 3 football fields (With end zones).

Molar Road Map: Conversion Factors for moles. Pg 323

# of Atoms = moles x 6.0 x 1023 atoms/mol

Mass (g) =

moles x atomic mass (from periodic table)

Volume of Gas = (at STP)

moles x 22.4 L / mol

STP = Standard Temperature and Pressure = 0° C, 101.3 kPa

= 1 atmospheric pressure at sea level on a freezing day.

Nest section uses:Molar Road Equations

# of Atoms =

moles x 6.0 x 1023 atoms/mol

Mass (g) =

moles x atomic mass (from periodic table)

How many hydrogen atoms are in 1.5 moles of hydrogen?

•

How many hydrogen atoms are in 1.5 moles of hydrogen?

1 atom H = 1 RP1 RP has 1 H atom

1.5 mol of H x 1 H atom = 1.5 mol H

1.5 mol H x 6.0 x 1023 atoms/mol = 9.0 x 1023 atoms

Always ask, is Sci Not and Sig Figs correct?

How many hydrogen atoms are in 1.5 moles of hydrogen?

Part 2: What is their mass?

How many hydrogen atoms are in 1.5 moles of hydrogen?

Part 2: What is their mass? 1 atom H = 1 RP

1 RP has 1 H atom

1.5 mol of H x 1 H atom = 1.5 mol H

Mass = moles x atomic mass

1.5 mol H x 1.0 g/mol

= 1.5 g H

How many hydrogen atoms are in 1.5 moles of water?

•

How many hydrogen atoms are in 1.5 moles of water?

1 molecule H2O = 1 RP1 RP has 2 H atoms

1.5 mol of H2O x 2 H atom / mol= 3.0 mol H

3.0 mol H x 6.02 x 1023 atoms/mol = 18.06 x 1023 atoms

= 1.8 x 1024 atoms

How many grams of hydrogen are in 1.5 moles of water?

•

How many grams of hydrogen are in 1.5 moles of water?

1 molecule H2O = 1 RP1 RP has 2 H atoms

1.5 mol of H2O x 2 H atom / mol= 3.0 mol H

Mass = moles x atomic mass

3.0 mol H x 1.0 g/mol

= 3.0 g H

How many moles of carbon are in 1.0 mole of C2S dicarbon

monosulfide?• A) 1 mole

• B) 2 moles

• C) 3 moles

• D) 4 moles

How many moles of carbon are in 1.0 mole of C2S dicarbon

monosulfide?• A) 1 mole

• B) 2 moles

• C) 3 moles

• D) 4 moles

What is the molar mass of 1 mol of calcium?

• 1 mole of any element is that compounds atomic mass expressed in grams

What is the molar mass of 1 mol of calcium?

• 1 mole of any element is that compounds atomic mass expressed in grams

• 1 mole Ca = 40.8 g / mol

• Because atomic mass is 40.8 amu

What is the molar mass of calcium hydroxide?

What is the molar mass of calcium hydroxide?

Ca(OH)2

List each atom and it’s quantity. Multiply by it’s atomic mass

add.Ca x 1 O x 2 H x 2 40 x 1 16 x 2 1 x 2

40 x 1 + 16 x 2 + 1 x 2 = = 74g

Common Atomic MassesH 1

C 12N 14O 16Ne 20 Fe 56 U 238

What is the molar mass of the following?

• Neon

• Dinitrogen monoxide

• Calcium chloride

Ne = 20gN2O=44g

CaCl2 = 110g

What is the molar mass of Mg(C2H3O2)2?

What is the molar mass of Mg(C2H3O2)2? 142g

• How many moles are in 55g of carbon?

• How many grams are in 22 moles of CO2?

• How many moles in 55g Ne? • How many moles in 55g oxygen?

• How many C atoms in 55g C4H10?

• How many H atoms in 155g HC2H3O2? • Answers on Following Slides

How many moles are in 55g of carbon?

How many grams are in 22 moles of CO2?

How many moles in 55g Ne?

How many moles in 55g oxygen?

How many C atoms in 55g C4H10?

How many H atoms in 155g HC2H3O2?

GAS VOLUME

1 mole of any gas at STP is

22.4L

MEMORIZE1 mole of any gas at STP is

22.4LRemember this WOD?

Volume of Gas = (at STP) moles x 22.4 L / mol

STP = Standard Temperature and Pressure = 0° C, 101.3 kPa

See mole box on page 301.

• What does STP stand for?

1 mole of any gas at STP is 22.4L.

• What does STP stand for?

• Standard temperature and pressure

• 0oC and 1 atm

• Where is it 1 atm?

• Why pick 0oC?

1 mole of any gas at STP is 22.4L.

• What does STP stand for?

• Standard temperature and pressure

• 0oC and 1 atm

• Where is it 1 atm? ANS: Sea Level

• Why pick 0oC? ANS: Freezing temp is easy to recreate.

How many atoms are in 44.8L of oxygen?

How many C atoms are in 2.2L of C3H8(g)?

• (g) at the end means it is a gas.

How many L are in 3.4 x 1023 CO2 molecules?

How many carbon monoxide moles are in 44.8L of CO?

• A) 1 mol

• B) 2 mol

• C) 1.00 mol

• D) 2.00 mol

Similar Test Question• One drop of H2O has a mass of 0.1g. How

many atoms of hydrogen are contained in a single drop of water?

Start 10.3

Percent composition

Percent composition = % of elements that make a compound

mass (element) ÷ mass (compound) x 100% =

Percent is about mass,

not volume, not moles, not atoms or molecules.

What is the percent composition of H2O?

• Use molar masses.• mass (element) ÷ mass (compound) x 100% =

» % Composition

• Hydrogen H / Total x 100%• 2g/18g x 100% = 11.1% Hydrogen• Oxygen O / Total x 100%• 16g/18g x 100% = 88.9% Oxygen• Total = 100% (or close because of rounding)

• 11.1% H and 88.9% Oxygen = 100%

What is the percent composition of carbon tetrafluoride?

Which has a higher percentage of carbon CO or C3H8OH?

Element Mass = Percent composition x Total Mass

A 175g sample of CO2 contains how many g of carbon?

Similar Test Question• How many grams of sodium can be

obtained from 42.5g of sodium nitrate?

Empirical formula = lowest ratio of elements in a compound, same %

composition

• C2H4 C4H8

Which of the following is an example of an empirical

formula?• A) CO

• B) C2H2

• C) C2Cl4

• D) C2H6

Test (like) Question

• The compound is 5.9% H. What is the molecular formula and empirical formula for this compound if it is only composed of oxygen and hydrogen?

Solution• 100% = 100g• 5.9%H = 5.9gH 94.1%O = 94.1gO

• Convert grams to moles• 5.9 mol H 5.9 mol O

• Divided by smallest to find EF (emp. Form.)• (5.9/5.9) 1mol H 1 mol O• 1g + 16g = 17g

Solution

• Multiply to find MF (molecular formula)

• OH(17g) x 2 = 34

• H2O2

Test (like) question

• 20.0g of sugar will produce how much carbon?

• Sugar = C12H22O11

Solution

• Find percent composition of Carbon

• 144g C / 342g C12H22O11 x 100%

• 42.1% C

• Find amount of carbon (decimal not %)

• 0.421 x 20g = 8.42g C

• 20.0g powdered sugar (C12H22O11) to 10 ml 18M sulfuric acid.

• Carbon and steam (water) will be produced.

• Add water/sodium bicarbonate to clean.

• Solid in trash.

Review Molar Mass

Gram atomic mass – atomic mass of 1 mol of an element

expressed in grams1 mol carbon = 12g

Gram molecular mass – mass of 1 mol of that compound

1 mole H2O = 18g

Gram formula mass – mass of 1 mol of an ionic compound

1 mol of NaCl = 58 g

Molar mass – the mass of 1 mole of any element or compound

(add atomic masses)

1 mol of NaCl = 58 g/mol23+35

1 mol carbon = 12g/mol12

1 mole H2O = 18g/mol 1+1+16