Unit 8~ Stoichiometry Most of your notebooks are NOT graded. Please make sure to leave them in the same stack (NEATLY) after taking notes for me to grade!

Unit 8~ StoichiometryUnit 8~ Stoichiometry

Most of your notebooks are NOT graded. Please make sure to leave them in the same stack (NEATLY) after taking notes for me to grade!

Most of your notebooks are NOT graded. Please make sure to leave them in the same stack (NEATLY) after taking notes for me to grade!

Vocabulary-Do these in your notebookVocabulary-Do these in your notebook

Actual Yield

Excess reactant

Limiting reactant

Mole ratio

Percent yield

Stoichiometry

Theoretical yield

Actual Yield

Excess reactant

Limiting reactant

Mole ratio

Percent yield

Stoichiometry

Theoretical yield

Reaction StoichiometryReaction Stoichiometry

Greek for “measuring elements”

Involves the mass relationships between reactants and products in a chemical reaction.

Based on balanced chemical equations & the Law of Conservation of Mass

Greek for “measuring elements”

Involves the mass relationships between reactants and products in a chemical reaction.

Based on balanced chemical equations & the Law of Conservation of Mass

4Fe(s) + 3O2 (g) 2Fe2O3(s) 4Fe(s) + 3O2 (g) 2Fe2O3(s)

Review:Atom – smallest unit of an element

Example: Fe

Molecule – group of atoms joined covalently ex. O2

Formula Unit – group of atoms joined ionically ex. Fe2O3

Review:Atom – smallest unit of an element

Example: Fe

Molecule – group of atoms joined covalently ex. O2

Formula Unit – group of atoms joined ionically ex. Fe2O3

4Fe(s) + 3O2 (g) 2Fe2O3(s) 4Fe(s) + 3O2 (g) 2Fe2O3(s)

4 atoms of iron reacts with 3 molecules of oxygen to produce 2 formula units of iron (III) oxide.

Remember coefficients also represent the number of moles.

So…. 4 moles of iron reacts with 3 moles of oxygen to produce 2 moles of iron (III) oxide.

4 atoms of iron reacts with 3 molecules of oxygen to produce 2 formula units of iron (III) oxide.

Remember coefficients also represent the number of moles.

So…. 4 moles of iron reacts with 3 moles of oxygen to produce 2 moles of iron (III) oxide.

Mole RatiosMole Ratios

A conversion factor that relates the amounts in moles of any 2 substances involved in a chemical reaction

Use the coefficients in the equationEach ratio can be expressed in 2 ways

A conversion factor that relates the amounts in moles of any 2 substances involved in a chemical reaction

Use the coefficients in the equationEach ratio can be expressed in 2 ways

Mole Ratios PracticeMole Ratios Practice

Determine all of the mole ratios in this equation:

2HCl + Mg H2 + MgCl2

2 mol HCl / 1 mol Mg

2 mol HCl / 1 mol H2

2 mol HCl / 1 mol MgCl2

1 mol Mg / 1 mole H2

Etc…

Determine all of the mole ratios in this equation:

2HCl + Mg H2 + MgCl2

2 mol HCl / 1 mol Mg

2 mol HCl / 1 mol H2

2 mol HCl / 1 mol MgCl2

1 mol Mg / 1 mole H2

Etc…

CO2 + 2 Li(OH) Li2CO3 + H2OCO2 + 2 Li(OH) Li2CO3 + H2O

1. Determine all of the mole ratios in equation above.Write them down on a separate sheet of paper

to turn in at the end of class for a grade.

You will be adding other answers to this paper as well

1. Determine all of the mole ratios in equation above.Write them down on a separate sheet of paper

to turn in at the end of class for a grade.

You will be adding other answers to this paper as well

Review Molar MassReview Molar Mass

Mass in grams of 1 mole of any substance. To calculate we must have the _______

_________ from the periodic table.

2. Calculate the Molar Mass of the following: (add this to your paper to turn in, this is review for you!)

Al2O3

CH4

Al2(SO4)3

Mass in grams of 1 mole of any substance. To calculate we must have the _______

_________ from the periodic table.

2. Calculate the Molar Mass of the following: (add this to your paper to turn in, this is review for you!)

Al2O3

CH4

Al2(SO4)3

Stoichiometry ~ type 1: Converting Moles to Moles

Stoichiometry ~ type 1: Converting Moles to Moles

Given substance is in Moles

Unknown substance is Moles

One conversion factor required



One conversion factor required

Moles Moles PracticeMoles Moles Practice

CO2 + 2 LiOH Li2CO3 + H2O

How many moles of Lithium hydroxide are required to react with 20 mol of CO2 ?

Given = 20 mol CO2

Unknown = Li(OH) in moles


How many moles of Lithium hydroxide are required to react with 20 mol of CO2 ?

Given = 20 mol CO2

Unknown = Li(OH) in moles

20 mol CO2

2 mol Li(OH) 1 mol CO2

X =

Type 2: Converting Moles to Grams

Type 2: Converting Moles to Grams


Unknown substance is Grams

2 Conversion factors required




Moles Grams Practice Moles Grams Practice


How many grams of Lithium hydroxide are required to react with 20 mol of CO2 ?

Given = 20 mol CO2

Unknown = Li(OH) in grams


How many grams of Lithium hydroxide are required to react with 20 mol of CO2 ?

Given = 20 mol CO2

Unknown = Li(OH) in grams

20 mol CO2 X 2 mol Li(OH) 1 mol CO2

X 24g Li(OH)

Type 3: Converting Grams to Moles

Type 3: Converting Grams to Moles

Given substance is in Grams






Grams Moles PracticeGrams Moles Practice


How many moles of Lithium hydroxide are required to react with 85 grams of CO2 ?

Given = 85 grams CO2 Unknown = Li(OH) in moles


How many moles of Lithium hydroxide are required to react with 85 grams of CO2 ?

Given = 85 grams CO2 Unknown = Li(OH) in moles

85g CO2 X 144g X

2 mol Li(OH) 1 mol CO2

Type 4: Converting Grams to Grams

Type 4: Converting Grams to Grams







Grams Grams PracticeGrams Grams Practice


How many grams of Lithium hydroxide are required to react with 96 grams of CO2 ?

Given = 96 grams CO2 Unknown = LiOH in grams


How many grams of Lithium hydroxide are required to react with 96 grams of CO2 ?

Given = 96 grams CO2 Unknown = LiOH in grams

96g CO2 X 144g

X2 mol Li(OH)1 mol CO2

X 24g =

Use this equation for #1-3Use this equation for #1-3

N2 + 3H2 2NH3

1. How many moles of nitrogen (N2) are required to produce 16 moles NH3?

2. How many moles of hydrogen (H2) are required to produce 96.5 grams of NH3?

3. How many grams of NH3 are produced from the reaction of 8 moles of nitrogen?

N2 + 3H2 2NH3

1. How many moles of nitrogen (N2) are required to produce 16 moles NH3?

2. How many moles of hydrogen (H2) are required to produce 96.5 grams of NH3?

3. How many grams of NH3 are produced from the reaction of 8 moles of nitrogen?

Use this Equation for Questions 1-3

Cu2O + 2HCl 2CuCl + H2O

Use this Equation for Questions 1-3

Cu2O + 2HCl 2CuCl + H2O

1. How many moles of CuCl are produced from 548 grams of Cu2O?

2. How many grams of HCl are required to react with 35 grams of Cu2O?

3. How many moles of CuCl are produced from 5 moles of HCl?

1. How many moles of CuCl are produced from 548 grams of Cu2O?

2. How many grams of HCl are required to react with 35 grams of Cu2O?

3. How many moles of CuCl are produced from 5 moles of HCl?

ReactantsReactants

Reactions are rarely carried out with exactly the required amounts of each reactant.

Limiting Reactant – the reactant that limits the amounts of the products that can form (It is used up first)

Excess Reactant – the substance that is not used up completely in a reaction.

Reactions are rarely carried out with exactly the required amounts of each reactant.

Limiting Reactant – the reactant that limits the amounts of the products that can form (It is used up first)

Excess Reactant – the substance that is not used up completely in a reaction.

Consider this. . .Consider this. . .

If you are given one dozen loaves of bread, a gallon of mustard and three pieces of salami, how many salami sandwiches can you make?

Now DECIDE:

What is the limiting reactant?

What is the excess reactant?

If you are given one dozen loaves of bread, a gallon of mustard and three pieces of salami, how many salami sandwiches can you make?

Now DECIDE:

What is the limiting reactant?

What is the excess reactant?

Determining the Theoretical Yield & Limiting Reactant

Determining the Theoretical Yield & Limiting Reactant

You must do 2 stoichiometry problems.Start each problem with one of the

reactants.The one that produces the least product (in

grams) is the limiting reactant.

EXAMPLECopper reacts with sulfur to form copper ( I

) sulfide. If 10.6 g of copper reacts with 3.83 g S how much product will be formed?

You must do 2 stoichiometry problems.Start each problem with one of the

reactants.The one that produces the least product (in

grams) is the limiting reactant.

EXAMPLECopper reacts with sulfur to form copper ( I

) sulfide. If 10.6 g of copper reacts with 3.83 g S how much product will be formed?

If 10.6 g of copper reacts with 3.83 g S. How many grams of product will be formed?

2Cu + S Cu2S

If 10.6 g of copper reacts with 3.83 g S. How many grams of product will be formed?

2Cu + S Cu2S

10.6 g Cu 63.55g Cu 1 mol Cu

2 mol Cu 1 mol Cu2S

1 mol Cu2S

159.16 g Cu2S

= 13.3 g Cu2S

3.83 g S 32.06g S 1 mol S

1 mol S 1 mol Cu2S

1 mol Cu2S

159.16 g Cu2S

= 19.0 g Cu2S

= 13.3 g Cu2S

Cu is Limiting Reagent

Percent YieldsPercent Yields

The amount of product made in a chemical reaction.

There are three typesActual yieldTheoretical yieldPercent yield Percent yield

The amount of product made in a chemical reaction.

There are three typesActual yieldTheoretical yieldPercent yield Percent yield

Actual yield- what you get in the lab when the chemicals are mixed (actual measured amount you get)

Theoretical yield- what the balanced equation tells you, you should make (max. amount that can be made given perfect conditions – involves calculations).

Percent yield Percent yield – – the ratio of actual yield to the ratio of actual yield to theoretical yield.theoretical yield.Percent yieldPercent yield = Actual x 100 = %

Theoretical

Actual yield- what you get in the lab when the chemicals are mixed (actual measured amount you get)

Theoretical yield- what the balanced equation tells you, you should make (max. amount that can be made given perfect conditions – involves calculations).

Percent yield Percent yield – – the ratio of actual yield to the ratio of actual yield to theoretical yield.theoretical yield.Percent yieldPercent yield = Actual x 100 = %

Theoretical

Percent Yield Cont.Percent Yield Cont.

Can never be more than 100% First determine the limiting reactant, this will

tell you the theoretical yield. Actual yield will be given to you in the

problem. Then use the Equation:

Percent yieldPercent yield = Actual x 100 = % Theoretical

Can never be more than 100% First determine the limiting reactant, this will

tell you the theoretical yield. Actual yield will be given to you in the

problem. Then use the Equation:

Percent yieldPercent yield = Actual x 100 = % Theoretical

Example ProblemExample Problem

C6H6 + Cl2 C6H5Cl + HCl

When 36.8 g of C6H6 reacts with 11.5 g of Cl2 what is the limiting reactant and theoretical yield? If the actual yield is of C6H5Cl is 12.0 g what is the percent yield of C6H5Cl?

C6H6 + Cl2 C6H5Cl + HCl

When 36.8 g of C6H6 reacts with 11.5 g of Cl2 what is the limiting reactant and theoretical yield? If the actual yield is of C6H5Cl is 12.0 g what is the percent yield of C6H5Cl?

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Unit 8~ Stoichiometry Most of your notebooks are NOT graded. Please make sure to leave them in the same stack (NEATLY) after taking notes for me to grade!