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*Lesson 7.8:  How much CO2 is added to the atmosphere from combustion?  

Review:

  1. What did we learn last class about weather, the atmosphere and the ideal gas law last lesson?

  2. Complete the IMT for Lesson 7.

Part 1: What is your car’s carbon emissions?

  • Use the link to calculate your emissions per year. Scroll down the page until you see “Car Carbon Footprint Calculator”.  How many pounds of emissions are produced by your vehicle.  How can you account for these emissions?

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  • Look at the graph above.  What do you notice?  What do you wonder?

Part 2: Can we predict the mass of a product formed from a simple chemical reaction? Watch Stoichiometry Made Easy Video and answer the questions below.

  • Why is the mole used so extensively in  stoichiometry?

  • Define Stoichiometry

  • How many slices of bread are in 7 sandwiches

7 sandwich                      

  • What does the balanced equation tell us?

  • Write the balanced equation for the Haber Process: ___N2(g) + ___H2(g) → ___NH3(g)

  • 1 molecule of N2  reacts with ____ molecules of H2 and produces ____ molecules of NH3.

  • 10 molecules of N2  react with ____ molecules of H2 and produce ____ molecules of NH3.

  • How many moles of N2 do you need to make 10 moles of NH3?

10 mol NH3               

  • How many moles of NH3 can you make from 0.37 moles of H2?

0.37 mol H2              

Here is a Road Map on how to solve any stoichiometry problem.  Remember moles are necessary because it is a standardized unit amongst all compounds and elements.  When doing stoichiometry problems you always have to convert your known value to moles.  The ratio is used  to convert to moles of unknown substance, which will help you to convert to any other unit.  Use the Road Map to help you with problems.   

Sample Problems

__ H2(g)    +          __ O2(g)   →             __ H2O(l)

  2. How many grams of _______ are in 1 mole? 

  3. hydrogen gas(H2) = 

  4. oxygen gas(O2) = 

  5. water(H2O) =

  6. How many moles of water are produced from 2 moles of hydrogen gas? 

2 mol H2               

  1. How many moles of water are produced from 2 moles of oxygen gas? 

2 mol O2               

  1. How many moles of hydrogen and oxygen do you need to produce 10 moles of water? 

10 mol H2O               

10 mol H2O               

For the next few problems, remember to use the road map to determining how to solve. 

  1. How many grams of water can you produce if you start with 38.2 grams of  O2(g) and excess H2(g) (hint: use the steps above! )? 

  2. How many grams of O2(g) do you need to make 50.0g of water?

  3. How many grams of H2(g) do you need to make 50.0g of water? 

4.  Now, let’s try with the combustion of methane…

__ CH4(g)   +   __ O2(g)   →     __ CO2(g) +  __ H2O(l)

  1. How many grams of _______ are in 1 mole? 

  2. methane gas(CH4) = 

  3. oxygen gas(O2) = 

  4. Carbon dioxide gas (CO2) = 

  5. water(H2O) =

b. How many moles of carbon dioxide are produced from 1 mole of methane gas? 

c. How many moles of water are produced from 1 mole of methane gas? 

d. How many moles of methane and oxygen do you need to produce 10 moles of carbon dioxide? 

e. How many grams of carbon dioxide can you produce if you start with 121.2 grams of  CH4(g) and excess O2(g)?

f. How many grams of CH4(g) do you need to make 100.0g of carbon dioxide?

g. How many grams of CH4(g) do you need to make 200.0g of water? 

Part 3: Stoichiometry Practice 

Use this equation for all calculations: ___C2H4(g) + ___O2(g) → ___CO2(g) + ___H2O(g)

  1. Calculate the number of grams of C2H4 that are required to produce 112.0 g H2O. (ans 87.11 g)

  2. Calculate the number of grams of CO2 that can be produced from 12.5 g of O2. (assume excess C2H4) (ans 11.5 g)

  3. This reaction was confined to a container with a pressure of 1.00 atm, and a temperature at 298 K. Calculate the number of liters of CO2 that are produced from 112.0 g C2H4 assuming the container remains closed. (Hint: use PV = nRT) (ans 196 L)

Part 4: Stoichiometry Application:  

How many liters of CO2 does the combustion of 1 gallon of gasoline produce?

Combustion reactions use a fuel, usually, a hydrocarbon that reacts with excess oxygen to form carbon dioxide gas and water vapor.  It has the generic equation CxHy + O2 → CO2 + H2O

Assume gasoline is primarily octane (C8H18).  Write the balanced equation for the combustion of octane.

2C8H18 + 25O2 → 16CO2 + 18H2O

Claim: 1 gallon of gasoline burned in a combustion engine will produce ~4900 L of CO2 gas

Useful/Helpful information:

  • Density of gasoline = 0.7550 kg/L

  • 1 gallon = 3.790 L so 1 gallon of gasoline has a mass of 2.860 kg

  • Gasoline is 84% Carbon 16% Hydrogen and has a molar mass of 114.0 g/mol

  • The combustion of gasoline will produce carbon dioxide and water.  

Calculations (Show your work)

  1. Using your evidence from above, calculate the number of grams of gasoline in one gallon.

  2. Convert your grams to moles of CO2.

  3. Convert your moles of carbon dioxide to L of carbon dioxide using PV = nRT. Use STP, standard temperature and pressure to solve(273K and 1 atm)

Use this table to organize your thoughts.

Question: How many liters of CO2 does the combustion of 1 gallon of gasoline produce?

Claim: one gallon of gasoline produces ______ L of CO2

Scientific Principles: stoichiometry shows _________

Evidence: (Data/Observations)

Reasoning: How do the evidence and the scientific principle(s) support the claim

We know that

or We saw that

Therefore

Write a CER paragraph that answers the question with a claim, evidence, and reasoning with scientific principles.

NEXT STEPS:

  1. Reflect on today’s question: How much CO2 is added to the atmosphere from combustion? 

  2. Reflect on the unit question, how does today’s activity relate to the unit question? 

  3. Make sure all parts of the L7.8 student sheet are complete.   Make a copy of you CER paragraph, save as a pdf, and submit.

**

Last update: June 5, 2023
Created: June 5, 2023