Mole Review 1.) Calculate the number of moles in 60.4L of O - PowerPoint Presentation

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Mole Review

1.) Calculate the number of moles in 60.4L of O2.2.) How many moles are there in 63.2g of Cl2?

60.4L O

2

22.4L O

2

1 mol O2

= 2.7 mol O2

63.2g Cl

2

70g Cl

2

1mol Cl2

= 0.903mol Cl2

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Ch.

9Math In ChemistryStoichiometry

Slide3

Tiny Tyke Tricycle Company

F + S + 3W + H + 2P

→ FSW

3

HP

2

Scheduled to make 640 tricycles. How many wheels should they order?

Proportional Relationships

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Proportional Relationships

I have 5 eggs. How many cookies can I make?3/4 c. brown sugar

1 tsp vanilla extract

2 eggs

2 c. chocolate chipsMakes 5 dozen cookies.

2 1/4 c. flour

1 tsp. baking soda1 tsp. salt

1 c. butter3/4 c. sugar

5 eggs

5 doz.

2 eggs

= 12.5 dozen cookies

Ratio of eggs to cookies

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Proportional Relationships

Stoichiometrymass relationships between substances in a chemical reactionfor example: you can determine the amount of a compound required to make another compound

based on the mole ratio

Mole

Ratioindicated by coefficients in a balanced equation

2 Mg + O

2

 2 MgO

2 Moles of magnesium react with 1 mole of oxygen to form 2 moles of magnesium oxide.

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2 Mg + O

2  2 MgO

What would be the mole ratio of magnesium to magnesium oxide?

2 : 2

Conversion factor = 2 mol Mg 2 mol MgO

What would be the mole ratio of oxygen to magnesium? 1 : 2Conversion factor = 1 mol O2

(Mole Ratio) 2 mol Mg

Slide7

Practice

5 F2 + 2NH

3

 N

2

F4

+ 6HF1. What is the mole ratio of NH

3 to F2? Write the mole ratio as a conversion factor.2. What is the mole ratio of HF to N2

F4?Write the mole ratio as a conversion factor.

2:5

2mol NH

35mol F2

6:1

6mol HF

1mol N2

F4

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Stoichiometry Steps

1. Write a balanced equationIdentify known & unknown.

3. Convert known to mole (if necessary), line up conversion factors.

4. Use Mole Ratio.

5. Convert moles to unknown unit (if necessary).6. Calculate and write units.

known

Mol of known

Mol of unknown

Mole ratio- get from equation

Mol of unknown

Units of unknown

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Mole - Mole Stoichiometry

Formula: known mol mol unknown mol known Write the known and unknown.

Use the balanced equation to find the mole ratio.

Calculate.

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__S + __O

2 → __SO3

Write the equation.

Balance the equation.

How many moles of SO3

are produced when there are 4.5 moles of S?Known =

Unknown =

Mole-Mole Examples

#1

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2C

3H7OH + 9O2 → 6CO2 + 8H2O

Write the equation.

Calculate

the

moles of oxygen needed to react with 3.40 moles of isopropyl alcohol.

Mole-Mole Examples

#2

Isopropyl alcohol (C

3H7

OH) burns in the air to this equation:

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2C

3H7OH + 9O2 → 6CO2 + 8H2O

Find the moles of water when 6.20 mol O

2

reacts with C3H7

OH.

Mole-Mole Examples

#3

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Mass-Mass Stoichiometry

Mass of reactants equals the mass of products, Law of Conservation of MassONLY mass and atoms are conserved in every chemical reaction1. Write the known and unknown.2. Find the molar mass of the known and unknown substances.3. Use mole and molar mass conversion factors from Ch. 7 and mole ratios from the balanced equation to solve.

Known g

1 mol Known

Molar mass

Known

mol unknown

mol known

Mol ratio-

get from equation

Molar mass unknown

1 mol unknown

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Mass-Mass Stoichiometry

#1The reaction of fluorine with ammonia produces dinitrogen tetrafluoride and hydrogen fluoride.5F2 + 2 NH3

→ N2

F4 + 6HF

How many grams of NH3 are required to produce 7.38g HF?

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Mass-Mass Stoichiometry

#25F2 + 2 NH3 → N2

F4

+ 6HFHow many grams of N

2F4

can be produced from 265g F2?

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Mass-Mass Stoichiometry

#32C2H2 + 5O2

→ 4CO2

+ 2H2O

How many grams of oxygen are required to burn 52.0g C2

H2?

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Volume-Volume Stoichiometry

Formula to use:Known (L) 1 mol known mol unknown 22.4 L unknown 1 22.4 L known mol known 1 mol unknownWrite the known and unknown.

Use mole and volume conversion factors from Ch. 7 and the mole ratios from the balanced equation to solve.

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C

3H8 + 5O2 → 3CO2 + 4H2O

If

25

liters of oxygen are consumed in the above reaction, how many liters of carbon dioxide are produced?

Volume-Volume Example

#4

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Mole - Mole

Known

mol of unknown

mol of known

Mol Ratio – from equation

Mass - Mass

Known

g

molar mass

known

1 mol known

mol of unknown

mol of known

1 mol unknown

molar mass

unknown

Known

L

22.4 L

known

1 mol known

mol of unknown

mol of known1 mol unknown22.4 L unknownparticles6.02 × 1023 particles6.02 × 1023 particlesOROROROtherFormulas to Use

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Stoichiometry Problems

How many moles of KClO3 must decompose in order to produce 9 moles of oxygen gas?

9 mol O2

2 mol KClO

3

3 mol O

2

= 6 mol

KClO3

2KClO

3  2KCl + 3O

2Known: 9 moles O2

Unknown: moles KClO3

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Stoichiometry Problems

How many grams of KClO3 are required to produce 9.00 L of O2 at STP?

9.00 L

O

2

1 mol

O

2

22.4 L

O2

=

32.68 g

KClO3

2 mol

KClO

3

3 mol

O2

122 g

KClO

3

1 molKClO32KClO3  2KCl + 3O2Known: 9.00 L O2Unknown: g KClO3

Slide22

Stoichiometry Problems

How many grams of silver will be formed from 12.0 g copper?

12.0g Cu

1 mol

Cu

64

g

Cu

= 40.5 g

Ag

Cu + 2AgNO

3  2Ag + Cu(NO3

)2

Known: 12.0 g Cu Unknown: g Ag

2 mol

Ag

1 molCu

108 g

Ag

1 mol

Ag

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Stoichiometry Problems

How many grams of silver will be formed from 12.0 g copper?

12.0

g Cu

1 mol

Cu

64

g Cu

= 40.5 g

Ag

Cu + 2AgNO

3  2Ag + Cu(NO3

)2

Known: 12.0 g Cu Unknown: g Ag

2 mol

Ag

1 molCu

108 g

Ag

1 mol

Ag

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Limiting Reactants/Reagents

Available Ingredients4 slices of bread1 jar of peanut butter1/2 jar of jelly

Limiting

Reactant/Reagents

bread

Excess

Reactants/Reagents

peanut butter and jelly

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Limiting Reactants/Reagents

Limiting Reactant/Reagentused up in a reactiondetermines the amount of product

Excess Reactant/Reagentadded to ensure that the other reactant is completely used up

cheaper & easier to recycle

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To Determine Limiting Reagents

1. Write a balanced equation.2. For each reactant, calculate the amount of product formed.3. Smaller answer indicates:limiting reactant

actual amount of product

Slide27

Limiting Reagents

79.1 g of zinc react with 0.90 L of HCl. Identify the limiting and excess reactants. How many liters of hydrogen are formed at STP?

Zn + 2HCl

 ZnCl2

+ H2

79.1 g

? L

0.90 L

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Limiting Reagents

79.1g Zn

1 mol

Zn

65

g Zn

=

27.26 L

H2

1 mol

H

2

1 molZn

22.4 L

H

2

1 mol

H

2

Zn + 2HCl

 ZnCl

2

+ H2 79.1 g? L0.90 L

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Limiting Reagents

0.90L HCl

1 mol

HCl

22.4

L HCl

= 0.45 L

H

2

1 mol

H

22 mol

HCL

22.4 L

H

2

1 mol

H

2

Zn + 2HCl

 ZnCl

2

+ H2 79.1 g? L0.90 L

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Limiting Reagents

Zn: 27.26 L H2

HCl: 0.45 L H

2

Limiting

reagent: HClExcess reagent: Zn

Slide31

Percent Yield

Percent yield- the ratio of the actual yield to the theoretical yieldActual yield- the amount of product formed when a reaction is carried out in the laboratoryTheoretical yield- the calculated amount of product formed during a reaction (mathematical calculation used to make answer keys)

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Percent Yield

calculated on paper

measured in lab

Slide33

Percent Yield

When 45.8 g of K2CO3 react with excess HCl, 46.3 g of KCl are formed. Calculate the theoretical and % yields of KCl.

K

2CO3 + 2HCl  2KCl + H

2O + CO2

45.8 g

? g

actual: 46.3 g

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B. Percent Yield

45.8 gK2CO3

1 mol

K

2

CO

3

138 gK2CO3

=

49.12

g KCl

2 mol

KCl

1 mol

K2CO3

74

g

KCl

1 mol

KCl

K

2

CO3 + 2HCl  2KCl + H2O + CO2 45.8 g? gactual: 46.3 gTheoretical Yield:

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B. Percent Yield

Theoretical Yield = 49.12 g KCl

% Yield =

46.3 g

49.12

g

 100

=

94.3%

K

2CO3 + 2HCl  2KCl + H

2O + CO2

45.8 g

49.12

g

actual: 46.3 g