4.06
Stoichiometry
Solving stoichiometry equations
Please watch the video on stoichiometry to see how to solve
this type of problem.
http://bit.ly/ZtW8Uy
General steps:
1. Is the equation balanced? If not, balance it.
2. Make a list of what you know and what you are solving for.
3. Start the “math” by writing down what you are given.
4. Use the conversion factors (molar mass; molar ratio) to convert
what you started with to what you need
– May need more than 1 step
Click the link to download notes on stoichiometry:
http://bit
.ly/YTtQ
87
General Flowchart
Click the star to save
a copy of this flow chart
http://bi
t.ly/YeiA
6c
What are you given?
Where do you need to go?
Mark your “starting” and “final” destinations and
“Map” out your route!
Using Molar Mass – Convert Grams “A” to Moles “A”
Lesson 2.04/3.09 Review: How many moles of oxygen
are in 43.6 grams of oxygen? (from lesson 3.06)
? = moles O2
Given = 43.6 g O2
Find the molar mass of O2 on the periodic table. Since there are
2 oxygen atoms, 2 x 16 g/mol O2 = 32 g/mol O2
Set up your problem
43.6 g O2 x 1 mol O2 = 1.36 mol O2
32 g O2
Using Molar Mass – Convert Moles “A” to Grams “A”
Your turn:
Lesson 2.04/3.09 Review: How many grams of
calcium are in 1.25 moles of calcium?
Watch the video to check your answer after trying this problem.
http://bit.ly/XjemO1
Using Molar Mass – Convert Grams “A” to Moles “B”
How many moles of oxygen gas can be formed from the
decomposition of 34.45 g of water?
2H2O  2H2 + O2
Watch the video to check your answer after trying this problem.
http://bit.ly/10DV1I2
Using Molar Mass – Convert Moles “A” to Grams “B”
How many grams of nitrogen gas are needed to form
2.56 moles of ammonia?
N2 + 3H2  2NH3
Watch the video to check your answer after trying this problem.
http://bit.ly/W1UflC
Using Molar Ratio – Convert Moles “A” to Moles “B”
How many moles of aluminum hydroxide are needed to react
completely with 12.3 moles of nitric acid?
Al(OH)3 + 3HNO3 → 3H2O + Al(NO3)3
Watch the video to check your answer after trying this problem.
http://bit.ly/ZfUkQw
All Together Now: Convert Grams of “A” to Grams of “B”
How many grams of chlorine gas can be produced when 62.3 grams of
aluminum chloride decompose?
2AlCl3 → 2Al + 3Cl2
Watch the video to check your answer after trying this problem.
http://bit.ly/15Icezi
All the Fun Ways to do “Stoichiometry”
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Convert Grams “A” to Moles “A” – 1 step
Convert Moles “A” to Grams “A” – 1 step
Convert Grams “A” to Moles “B” – 2 steps
Convert Moles “A” to Grams “B” – 2 steps
Convert Moles “A” to Moles “B” – 1 step
Convert Grams of “A” to Grams of “B” – 3 steps
You Try
How many grams of nitrogen gas is needed to form
4.36 moles of ammonia?
N2 + 3H2  2NH3
You Try #2
How many grams of nitric acid are required to produce 124.6
grams of aluminum nitrate? Al(OH)3 + 3HNO3 → 3H2O + Al(NO3)3
Conclusion
Need more practice?
Check out the TWO awesome practice sections in
the “activity” tab of the lesson:
Thank You!
It has been great working with you on Stoichiometry. It is
very important for the rest of module 4 and module 5.
Please use our other Teaching Videos for the other lessons.
Don’t forget that you can use them to review previous
lessons too! There is a lot of extra support for chemistry on
your teacher’s announcement page!