# Unit 8 Stoichiometry Chapter 12.

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Unit 8 Stoichiometry Chapter 12

Today… Our Plan: Turn in: Forensic Farming Reading Fill Out Goal Sheet
Begin Lab Daily Challenge – Smore’s Stoichiometry Notes – Stoichiometry Conversions Worksheet #1 & Worksheet #2 Wrap Up - Pyramid Homework (Write in Planner): WS#1 & WS#2 Due Monday

Lab Day 1 Follow the procedure for Day 1 and begin recording observations Use the internet to answer the Pre-Lab Questions

ChEck out the blue man!

Daily Challenge French Toast Recipe: 4 slices of bread ¼ cup milk
1 egg 1 tsp. vanilla If you were making French Toast for 20 people how many eggs would you need?

Daily Challenge 4 slices of bread ¼ cup milk 1 egg 1 tsp. vanilla
If you were making French toast for 12 people how many teaspoons of vanilla would you use?

Daily Challenge 4 slices of bread ¼ cup milk 1 egg 1 tsp. vanilla
If you have 1 cup of milk, how many slices of French Toast can you make?

Stoichiometry Stoy-key-ahm-a-tree

What does it mean? Comes from the combination of the Greek words stoikheioin, meaning “element”, and metron, meaning “to measure”

Definition The study of the quantitative, or measurable, relationships in a chemical reaction.

Importance Using stoichiometry, you can determine the quantities of reactants & products in a reaction from the BALANCED equation. Like the Recipe!

Coefficients… Do show the number of moles of each substance involved in the rxn. Do Not indicate the actual number of grams of the substance.

On both the reactant and product side!
Example N2 + 3H2 --> 2NH3 Atoms N Atoms H 2 6 On both the reactant and product side!

Example Molecule N2 1 Molecules H2 Molecules NH3 3 2
N2 + 3H2 --> 2NH3 Molecule N2 Molecules H2 Molecules NH3 1 3 2

Example N2 + 3H2 --> 2NH3 1 Mole N2 Moles H2 Moles NH3 3 2

Example N2 + 3H2 --> 2NH3 28 Grams N2 Grams H2 Grams NH3 6 34

Challenge Which were conserved? Atoms and Mass, but NOT Moles and Molecules!

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

Molar Ratios from Last Example…
N2 + 3H2 --> 2NH3 3 moles H2 1 mole N2 2 moles NH3 3 moles H2 1 mole N2 2 moles NH3

The Stoichiometry Map Mass Moles Given Volume Moles Unknown Molecules
Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole

Mole --> Mole Conversions
The conversion of moles of one type of substance to moles of another type of substance.

To Solve: Moles Given Molar Ratio Equation Moles Unknown

Example H2 + I2 --> 2HI If 4 moles of H2 react, how many moles of HI will form?

Example 2 moles HI 4 moles H2 X = 8 moles HI 1 mole H2
H2 + I2 --> 2HI 2 moles HI 4 moles H2 X = 8 moles HI 1 mole H2

Example 2 If 0.8 moles of HI form, how many moles of I2 were used in the rxn?

Example 2 1 mole I2 0.8 moles HI X = 0.4 moles I2 2 moles HI
H2 + I2 --> 2HI 1 mole I2 0.8 moles HI X = 0.4 moles I2 2 moles HI

Try it Out! 2H2 + O2 --> 2H2O If 1.3 moles of H2O form, how many moles of O2 were used in the rxn? (0.65 moles) If 0.21 moles of H2 react, how many moles of H2O will form? (0.21 moles)

Answer to #1 1 moles O2 0.65 moles O2 1.3 moles H2O X = 2 moles H2O

Answer #2 2 moles H2O 0.21 moles H2 = 0.21 moles H2O X 2 moles H2

Mole --> Mass Conversions
Given the moles of one substance & asked to determine the mass of another substance.

To Solve: Moles Given Mass Unknown Moles Unknown molar molar ratio
equation molar mass PT Moles Given Mass Unknown Moles Unknown

Example What mass of sucrose was used if 3 moles of water formed?
C6H12O6 +6O2 --> 6CO2 + 6H2O What mass of sucrose was used if 3 moles of water formed?

Example 90g C6H12O6 X C6H12O6 +6O2 --> 6CO2 + 6H2O 1 mole C6H12O6
3 moles H2O X X = 6 moles H2O 1 mole C6H12O6 90g C6H12O6

Example 2 What mass of carbon dioxide was used to form 5.0 moles of water?

Example 2 220 g CO2 C6H12O6 +6O2 --> 6CO2 + 6H2O 6 moles CO2
5.0 moles H2O X 44g CO2 = X 1 mole CO2 6 moles H2O 220 g CO2

Try it Out! N2O5 + H2O --> 2HNO3
What mass of water was used to form 2.5 moles of HNO3? (23 g H2O) What mass of HNO3 will form from moles of N2O5? (1512 g HNO3)

Answer to #1 23 g. H2O 18g. H2O 1 mole H2O 2.5 moles HNO3 X X =

Answer to #2 = 1512 g. HNO3 2 moles HNO3 63g. HNO3 12.00 moles N2O5 X
1 mole N2O5 1 mole HNO3 = 1512 g. HNO3

Mass-->Mole Conversions
Given mass of one substance and asked to find moles of another substance.

To Solve molar molar mass ratio PT Moles Mass equation Moles Given
Unknown

How many moles of NO were used to form 824g. NH3?
Example 2NO + 3H2 --> 2NH3 + O2 How many moles of NO were used to form 824g. NH3?

Example = 48.5 moles NO 1 mole NH3 2 moles NO 824g. NH3 X X 17g. NH3
2NO + 3H2 --> 2NH3 + O2 1 mole NH3 2 moles NO 824g. NH3 X X 17g. NH3 2 moles NH3 = 48.5 moles NO

How many moles of H2 were used to form 312 g of O2?
Example 2NO + 3H2 --> 2NH3 + O2 How many moles of H2 were used to form 312 g of O2? 1 mole O2 3 moles H2 312g. O2 X X 32g. O2 1 mole O2 = 29.3 moles H2

Isosceles \$300 \$200 Right Scalene \$250 Acute \$50 \$100 Equilateral \$150
\$100,000 Pyramid Isosceles \$300 Pencil \$200 Right Cougars Chemistry Scalene \$250 Have the pairs hold up their hand when they finish. Purple Acute \$50 \$100 Safety Shower Equilateral \$150 Mole Obtuse

Isosceles \$300 \$200 Right Scalene \$250 Acute \$50 \$100 Equilateral \$150
\$100,000 Pyramid Isosceles \$300 Stoichiometry \$200 Right Coefficient Molar Mass Scalene \$250 Have the pairs hold up their hand when they finish. Periodic Table Acute \$50 \$100 Balance Equilateral \$150 Ratio Obtuse

Today… Turn in: Worksheet #1 & Worksheet #2 Our Plan:
Conversions Table Review Notes – Mass to Mass Conversions Worksheet #3 Homework (Write in Planner): Worksheet #3 due next class

The Stoichiometry Map Mass Moles Given Volume Moles Unknown Molecules
Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole

Team Conversion review
As a group of 3 or 4, complete the problems on the team conversion review. Each student should have a different colored writing utensil and you should take turns doing the work.

The Stoichiometry Map Mass Moles Given Volume Moles Unknown Molecules
Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole

Mass-->Mass Conversions
Given the mass of one substance and asked to determine the mass of another substance.

To Solve: molar molar molar mass ratio mass Mass PT Moles Moles Mass
equation molar mass PT Mass Given Moles Given Moles Unknown Mass Unkn

Example Find the mass of table salt produced from 18.6g Na.
2Na + Cl2 -->2NaCl Find the mass of table salt produced from 18.6g Na.

Example = 47.3g NaCl 2Na + Cl2 --> 2NaCl 1 mole Na 2 moles NaCl
1 mole NaCl = 47.3g NaCl

Example 2Al + Fe2O3 --> Al2O3 + 2Fe Find the mass of aluminum oxide produced from 2.3g of aluminum.

Example = 4.3 g Al2O3 2Al + Fe2O3 --> Al2O3 + 2Fe 1 mole Al
1 mole Al2O3 102g Al2O3 X 2.3g. Al X X 27g. Al 2 mole Al 1 mole Al2O3 = 4.3 g Al2O3 2Al + Fe2O3 --> Al2O3 + 2Fe

Try it Out! Methane burns in air by the following reaction: CH4 + 2O2 --> CO2 + 2H2O What mass of water is produced by burning g of methane?

Example = 1,130 g H2O 1 mole CH4 2 mole H2O 18g H2O X 500.g CH4 X X

STOP! Complete Worksheet #3 by next class!

Today… Turn in: Worksheet #3 Our Plan: Questions on WS 1-3
Stoichiometry Team Review Quiz WS 1 – 3 Lab Day 2 Homework (Write in Planner): Finish missing worksheets

The Stoichiometry Map Mass Moles Given Volume Moles Unknown Molecules
Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole

Decanting…

Today… Turn in: Any Missing Worksheets Our Plan: Lab Day 3
Turn in Lab Today Homework (Write in Planner): Lab, if not done

Lab Helpful Hints #1 – 1000 mg = 1 g, 1000 mL = 1 L
#3 – Convert both the 1g AgNO3 and your g of Cu to g of Ag. The limiting reactant is the reactant that produces the least product. You will do 2 three step conversions to find the answer. # 5 & #6 – Percent yield = (actual/theoretical) x 100 WASH ALL SUPPLIES, RETURN TO SIDE TABLE, WIPE DOWN COUNTER, WASH HANDS!

Wrap Up Clicker Review

Today… Our Plan: Turn in: Metal in Water Lab Relay Race Review
Daily Challenge Notes – Stoichiometry of Gases and Molecules Worksheet #4 Homework (Write in Planner): WS#4 due next class

Daily Challenge How many liters are in 1 mole of a gas?
How many molecules are in 1 mole of any compound? For the reaction below, what mass of water can be produced from 1.5 moles of hydrogen? (27g) 2H2 + O2 --> 2H2O

The Stoichiometry Map Mass Moles Given Volume Moles Unknown Molecules
Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole

Volume --> Volume Conversions
Given the volume of one substance and asked to determine the volume of another substance.

To Solve: molar 22.4 L ratio Vol Vol Moles Moles equation 22.4 L Given
Unknown Vol Unkn 22.4 L

Conversion factor: 22.4 L/mole
Molar Volume Conversion factor: L/mole

STP is 0 degrees Celsius and 1 atm
Molar Volume You can only use the conversion factor 22.4 under very specific conditions. It must be a gas and it must be at STP (Standard Temperature and Pressure) STP is 0 degrees Celsius and 1 atm

How many moles of Helium are in a 3.7 L balloon at STP?
Sample Problem How many moles of Helium are in a 3.7 L balloon at STP?

Sample Problem 3.7 L x 1 mole = 0.17 mole 22.4 L

Practice Problem 2 CO + O2 --> 2 CO2
What volume of carbon dioxide will be produced from 2.6 L of oxygen at STP?

The Stoichiometry Map Mass Moles Given Volume Moles Unknown Molecules
Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole

Practice Problem 5.2 L CO2 2 CO + O2 --> 2 CO2 2.6 L O2 X
1 mole O2 X 22.4 L O2 2 mole CO2 X 1 mole O2 22.4 L CO2 = 1 mole CO2 5.2 L CO2

Practice Problem Using the same equation, what volume of carbon dioxide will be produced at STP from grams of carbon monoxide?

The Stoichiometry Map Mass Moles Given Volume Moles Unknown Molecules
Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole

Practice Problem 36.2 L CO2 2 CO + O2 --> 2 CO2 45.3 g CO X
1 mole CO X 28 g CO 2 mole CO2 X 2 mole CO 22.4 L CO2 = 1 mole CO2 36.2 L CO2

Try It Out! Using the same equation, what volume of oxygen is used to produce 19.3 grams of carbon dioxide at STP? (4.91 L)

Try it Out! 4.91 L O2 2 CO + O2 --> 2 CO2 19.3 g CO2 X 1 mole CO2 X
1 mole O2 X 2 mole CO2 22.4 L O2 = 1 mole O2 4.91 L O2

Molecule Stoichiometry Problems
You can do the same type of problems using molecules. Just use Avogadro’s Number!

Example In the reaction: H2 + O2 --> 2H2O if you have grams of hydrogen, how many molecules of water will form?

The Stoichiometry Map Mass Moles Given Volume Moles Unknown Molecules
Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole

Example = 1.5 x 1023 molecules H2O 2H2 + O2 --> 2H2O
1 mole H2 2 mole H2O X 0.50 g H2 X X 2 mole H2 2 g H2 1 mole H2O = 1.5 x 1023 molecules H2O 2H2 + O2 --> 2H2O

Real Life Applications
Cooking Planning outcomes of reactions Race cars/ mechanics

Real Life Applications
Treating an upset stomach Airbags Artists

Real Life Applications
Launching space shuttle Baking bread Engineering

STOP! Complete Worksheet #4 by next class period!

Today… Turn in: Get Worksheet #4 Out to Check Our Plan: Balloon Races
Limiting Reactant Notes Finish Balloon Races Handout Worksheet #5 Chemistry Cartoon Homework (Write in Planner): Worksheet 5 & Cartoon Due Next Class

HC2H3O2 + NaHCO3 --> NaC2H3O2 + CO2 + H2O.
Molecules Mass Volume Moles Given Moles Unknown Molar Ratio Equation 6.022 x 1023 Molar Mass PT 22.4 L/mole Pre Lab Review – The balanced equation for the reaction of baking soda and vinegar is: HC2H3O2 + NaHCO3 --> NaC2H3O2 + CO2 + H2O. How many liters of carbon dioxide can form from 3.00 g of baking soda (NaHCO3)? Show your work at the top of your lab.

Universal Indicator Chart

Lab Discussion What did you predict would happen?
What did happen? Why?

Smore’s Recipe 2 Graham Crackers 3 Pieces of Chocolate 1 Marshmallow
Daily Challenge Smore’s Recipe 2 Graham Crackers 3 Pieces of Chocolate 1 Marshmallow

Making Smores! If you have 4 graham crackers, 9 pieces of chocolate, and 7 marshmallows, how many smores can you make?

Which ingredient determined this?
Making Smores! Which ingredient determined this?

Making Smores! If you have 22 graham crackers, 27 pieces of chocolate, & 13 marshmallows, how many smores can you make?

Which ingredient determined this?
Making Smores! Which ingredient determined this?

Even in abundance, the reactants must still combine in proportion
Limiting Reactants Even in abundance, the reactants must still combine in proportion They follow stoichiometry.

Limiting Reactant Is the reactant that limits the amount of product formed in a chemical equation.

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

Importance of the Limiting Reactant
The quantities of products formed in a reaction are always determined by the quantity of the limiting reactant.

To Solve Write a balanced equation
Convert the mass of reactants to the mass of the product.

To Solve Whichever produces less product is the limiting reactant.

Example Identify the L.R when 10.0 g of water react with 4.50 g of sodium to produce sodium hydroxide & hydrogen gas.

Example 1 mol H2O 2 mol NaOH 40g NaOH 10.0 g H2O X X X 18g H2O
2H2O + 2Na --> 2NaOH + H2 1 mol H2O 2 mol NaOH 40g NaOH 10.0 g H2O X X X 18g H2O 2 mol H2O 1 mol NaOH = 22.2 g NaOH 1 mol Na 2 mol NaOH 40g NaOH 4.50 g Na X X X 23g Na 2 mol Na 1 mol NaOH = 7.83 g NaOH Na= L.R.

Try it Out! Identify the L.R when g HF are combined with 14.56g SiO2 in the following reaction: SiO2 + 4HF --> SiF4 + 2H2O

Try it Out! 2 mol H2O 1 mol HF 18g H2O X X X 20g HF 1 mol H2O 4 mol HF
SiO2 + 4HF -->SiF4 + 2H2O 2 mol H2O 1 mol HF 18g H2O 8.9 g HF X X X 20g HF 1 mol H2O 4 mol HF = 4.0 g H2O 1 mol SiO2 2 mol H2O 18g H2O 14.50g SiO2 X X X 60g SiO2 1 mol SiO2 1 mol H2O 8.700 g H2O = HF= L.R.

STOP Finish Balloon Races Questions Worksheet #5 Chemistry Cartoon

Chemistry Cartoons

Today… Turn in: Get Worksheet #5 Out to Check
Turn in Chemistry Cartoon - Basket Our Plan: L.R. Review Problem Percent Yield Notes Worksheet #6 Homework (Write in Planner): Worksheet #6 Due Tuesday/Wednesday

WS 6 #4 Acrylonitrile, C3H3N, is an important ingredient in the production of various fibers and plastics. Acrylonitrile is produced from the following reaction: C3H6 + NH3 + O2 --> C3H3N + H2O If 850 g of C3H6 is mixed with 300. g of NH3 and unlimited O2, to produce 850. g of acrylonitrile, what is the percent yield? You must first balance the equation. 91 %

Baseball’s Best! Babe Ruth played in baseball games in his career. He had hits in 8399 at bats what was his batting average?

Baseball’s Best! Hank Aaron played in baseball games in his career. He had hits in 12,364 at bats. What was his batting average?

Theoretical Yield is based on calculations
Percent Yield Theoretical Yield is based on calculations

Actual Yield is based on the actual chemical reaction (the lab)
Percent Yield Actual Yield is based on the actual chemical reaction (the lab)

The Formula % yield = Actual yield X 100 Theoretical yield

To Calculate Write equation
Calculate the mass of the product that should have been formed. (theoretical yield)

Plug numbers into the equation
To Calculate Plug numbers into the equation

Example Determine the % yield for the reaction between 2.80 g Al(NO3)3 & excess NaOH if 0.966g Al(OH)3 is recovered.

Example Write the equation: Al(NO3)3 + 3NaOH --> Al(OH)3 + 3NaNO3

Al(NO3)3 + 3NaOH --> Al(OH)3 + 3NaNO3
Example Calculate theoretical yield 78g Al(OH)3 2.80 g Al(NO3)3 1 mol Al(NO3)3 1 mol Al(OH)3 X X X 213g Al(NO3)3 1 mol Al(NO3)3 1 mol Al(OH)3 = 1.03 g Al(OH)3 Al(NO3)3 + 3NaOH --> Al(OH)3 + 3NaNO3

Example Plug numbers into equation 0.966g 100 % yield = X 1.03g = 93.8%

Try it Out! Determine the percent yield for the reaction between g N2 & excess H2 if 10.5g NH3 is produced.

N2 + 3H2 --> 2NH3 2 mol NH3 1 mol N2 17g NH3 15.0g N2 X X X 28g N2
= 18.2 g NH3 10.5g NH3 %yield = X 100 = 57.7% 18.2 g NH3

SOMETIMES…. You have to find the limiting reactant first.
Calculate amount of product for both reactants & whichever is less, use as theoretical yield.

STOP! Complete Worksheet #6 by next class!

Today… Turn in: Worksheet #6 Our Plan: Stoichiometry Lab Test
Test Review Homework (Write in Planner): Test Review due next class UNIT 8 TEST NEXT CLASS!

Today… Turn in: Get out Test Review Our Plan:
Questions on Test Review? Test Larry the Lawnchair Guy Reading Homework (Write in Planner): Larry Reading due next class

Some sample problems… Given the following reaction:
C3H8    +    5O2    >     3CO2      +     4H2O If you start with 14.8 g of C3H8 and 3.44 g of O2, determine the limiting reagent Given the following equation: H3PO4  +   3 KOH    >  K3PO4   +  3 H2O If 49.0 g of H3PO4 is reacted with excess KOH, determine the percent yield of K3PO4 if you isolate 49.0 g of K3PO4.

Another Percent Yield Example
Given the following equation: Al(OH)3  +3 HCl   --> AlCl3 + 3 H2O If you start with 50.3 g of Al(OH)3 and you isolate 39.5 g of AlCl3, what is the percent yield? H2SO4  +  Ba(OH)2   ---->  BaSO4  +  H2O If 98.0 g of H2SO4 is reacted with excess Ba(OH)2, determine the percent yield of if g of BaSO4 is formed.

Larry the lawnchair guy
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