Moles, Avogadro’s Number and Molar Mass Converting moles to molecules, atoms, and particles

Moles, Avogadro’s Moles, Avogadro’s Number and Molar MassNumber and Molar Mass

Converting moles to Converting moles to molecules, atoms, and molecules, atoms, and

particlesparticles

Can anyone define the Can anyone define the term mole?term mole?

MoleMole

SI unit used to measure the amount SI unit used to measure the amount of a substanceof a substance

equal to 6.02 x 10equal to 6.02 x 102323 atoms, atoms, molecules, or particlesmolecules, or particles Avogadro’s numberAvogadro’s number

Abbreviated by molAbbreviated by mol

Avogadro’s NumberAvogadro’s Number

6.02 X 106.02 X 102323

Used to count extremely small particles Used to count extremely small particles

Named in honor of Italian physicist Named in honor of Italian physicist Amedeo AvogardoAmedeo Avogardo

Determined the volume of one mole of a gasDetermined the volume of one mole of a gas

ConversionsConversions

Mole Mole Molecules, Atoms, or Molecules, Atoms, or Particles Particles

In order to convert moles to In order to convert moles to molecules atoms, or particles, you molecules atoms, or particles, you have to have to MULTIPLY the number of moles by Avogadro’s number (6.02 x 6.02 x 10102323)

Example: How many atoms are there in 4.0 moles?

How many atoms are there in 4.0 How many atoms are there in 4.0 moles?moles?

Moles Moles Atoms…MULTIPLY BY Atoms…MULTIPLY BY AVOGADRO’S NUMBERAVOGADRO’S NUMBER

2.4 x 1024 atoms

Molecules, Atoms, or Particles Molecules, Atoms, or Particles MolesMoles

In order to convert molecules, atoms, In order to convert molecules, atoms, or particles to moles, you have to or particles to moles, you have to DIVIDE the number of moles by Avogadro’s number (6.02 x 106.02 x 102323)

Example: How many moles are there in 7.14 x 102323 molecules?

How many moles are there in 7.14 How many moles are there in 7.14 x 10x 102323 molecules? molecules?

Molecules Molecules Moles…DIVIDE BY Moles…DIVIDE BY AVOGADRO’S NUMBERAVOGADRO’S NUMBER

1.19 moles

PracticePractice

How many molecules are there in How many molecules are there in 3.5 moles?3.5 moles?

Moles Moles Molecules…MULTIPLY BY Molecules…MULTIPLY BY AVOGADRO’S NUMBERAVOGADRO’S NUMBER

2.11 x 1024 molecules

How many particles are there in 9.6 How many particles are there in 9.6 moles?moles?

Moles Moles Particles…MULTIPLY BY Particles…MULTIPLY BY AVOGADRO’S NUMBERAVOGADRO’S NUMBER

5.78 x 1024 particles

How many moles are there in 5.75 How many moles are there in 5.75 x 10x 102424 atoms? atoms?

Atoms Atoms Moles…DIVIDE BY Moles…DIVIDE BY AVOGADRO’S NUMBERAVOGADRO’S NUMBER

9.55 moles

How many moles are there in 3.58 How many moles are there in 3.58 x 10x 102323 particles? particles?

Molecules Molecules Moles…DIVIDE BY Moles…DIVIDE BY AVOGADRO’S NUMBERAVOGADRO’S NUMBER

0.59 moles

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Molar MassMolar Mass

Molar MassMolar Mass

the mass in grams of one mole of the mass in grams of one mole of any pure substanceany pure substance

In other words, the molar mass of In other words, the molar mass of any element is equivalent to the any element is equivalent to the atomic mass of that elementatomic mass of that element

in units of grams per mole; g/molin units of grams per mole; g/mol

Calculating Molar MassCalculating Molar Mass

- To calculate the molar mass of a - To calculate the molar mass of a substance, you add the atomic mass substance, you add the atomic mass of every element in the compound of every element in the compound

The total atomic mass is the molar mass The total atomic mass is the molar mass of the substance. of the substance.

ExampleExample

What is the molar mass of N?What is the molar mass of N?

Step 1: determine the atomic massStep 1: determine the atomic massN: 14N: 14

Step 2: add unitsStep 2: add unitsg/molg/mol

molar mass = 14 g/molmolar mass = 14 g/mol

ExampleExample

What is the molar mass of COWhat is the molar mass of CO22??

Step 1: determine the mass of each elementStep 1: determine the mass of each elementC: 12C: 12O: 16 X 2O: 16 X 2

Step 2: add the masses to get the total atomic massStep 2: add the masses to get the total atomic mass12+16+16=4412+16+16=44

Step 3: add unitsStep 3: add unitsg/molg/mol

Molar mass = 44 g/molMolar mass = 44 g/mol

PracticePractice What is the molar mass of NaCl?What is the molar mass of NaCl?

58.5 g/mol58.5 g/mol

What is the molar mass of HWhat is the molar mass of H33O?O?

19 g/mol19 g/mol

What is the molar mass of HWhat is the molar mass of H22SOSO44??

98 g/mol98 g/mol

ENDEND

Mole Mole Gram Gram ConversionsConversions

ReviewReview MoleMole

SI unit used to measure the amount of a SI unit used to measure the amount of a substancesubstance

Abbreviate by molAbbreviate by mol

Molar massMolar mass

total atomic mass of every element in the total atomic mass of every element in the compoundcompound

Units: g/molUnits: g/mol

What is the molar mass of NHWhat is the molar mass of NH33? ?

Step 1: determine the mass of each Step 1: determine the mass of each elementelement N: 14N: 14 H:1 X 3H:1 X 3

Step 2: total the massesStep 2: total the masses 14+3=1714+3=17

Step 3: attach the unitsStep 3: attach the units 17g/mol17g/mol

Mole Mole Gram Conversions Gram Conversions

When given the number of moles, When given the number of moles, MULTIPLYMULTIPLY by the molar mass of the by the molar mass of the substance. substance.

What is the mass of 5 moles of HWhat is the mass of 5 moles of H22O?O?

What is the mass of 5.O moles of What is the mass of 5.O moles of HH22O?O?

Step 1: Write the givenStep 1: Write the given

Step 2: Multiply by molar massStep 2: Multiply by molar mass

Step 3: Cancel the unitsStep 3: Cancel the units

Step 4: SolveStep 4: Solve

90 grams H90 grams H22OO

Gram Gram Mole Conversions Mole Conversions

When given the number of moles, When given the number of moles, DIVIDEDIVIDE by the molar mass of the by the molar mass of the substance. substance.

How many moles are equivalent to How many moles are equivalent to 50g N?50g N?

How many moles are equivalent to How many moles are equivalent to 50g N?50g N?

Step 1: Write the givenStep 1: Write the given

Step 2: Divide by the molar massStep 2: Divide by the molar mass

Step 3: Cancel the unitsStep 3: Cancel the units

Step 4: SolveStep 4: Solve

3.57 moles N3.57 moles N

Practice Practice

What is the mass of …What is the mass of … 2.22 mol Ti2.22 mol Ti

106 g Ti106 g Ti

1.22 X 101.22 X 102323 mol Ag mol Ag

1.32 X 101.32 X 102525 g Ag g Ag

4.5 mol H4.5 mol H22SOSO44

441 g H441 g H22SOSO44

How many moles are consumed How many moles are consumed in…in…

5.62 g Kr5.62 g Kr

0.0669 mol Kr0.0669 mol Kr

55 g As55 g As

0.73 mol As0.73 mol As

7.5 g NaCl7.5 g NaCl

0.128 mol NaCl0.128 mol NaCl

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Particles Particles Gram Conversions Gram Conversions

Remember, particles, atoms, and Remember, particles, atoms, and molecules are all the samemolecules are all the same

To convert particles to grams…To convert particles to grams… 11stst: convert particles to moles: convert particles to moles 22ndnd: convert moles to grams: convert moles to grams

ReviewReview

When converting from moles to When converting from moles to atoms, molecules, or particles, you atoms, molecules, or particles, you must MULTIPLY by Avogadro’s must MULTIPLY by Avogadro’s number.number.

When converting atoms, particles, or When converting atoms, particles, or molecules to moles, you must DIVIDE molecules to moles, you must DIVIDE by Avogadro’s number. by Avogadro’s number.

What is the mass of 2.5 X 10What is the mass of 2.5 X 1023 23

atoms of Hatoms of H22O?O? Step 1: convert atoms to molesStep 1: convert atoms to moles

Step 2: convert moles to gramsStep 2: convert moles to grams

Grams Grams Particles Conversions Particles Conversions

Once again, remember particles, Once again, remember particles, atoms, and molecules are all the atoms, and molecules are all the samesame

To convert grams to particles…To convert grams to particles… 11stst: grams to moles: grams to moles 22ndnd: convert moles to particles: convert moles to particles

How many molecules are in 4.5 g How many molecules are in 4.5 g C?C?

Step 1: Convert grams to molesStep 1: Convert grams to moles

Step 2: Convert moles to molecules Step 2: Convert moles to molecules

PracticePractice

How many grams are in 5.0 X 10How many grams are in 5.0 X 102424 atoms atoms of K?of K?

What is the mass of 8.5 X 10What is the mass of 8.5 X 102323 molecules molecules of NHof NH22??

How many particles are in 3.75 g Ca?How many particles are in 3.75 g Ca?

How many molecules are in 96 g HBrHow many molecules are in 96 g HBr22??

PracticePractice

On your own, work pg. 347: On your own, work pg. 347:

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