1. Chemical Quantities

2. Reading Quiz
Calculate the moles of CO2 formed when 4.30 mol of C3H8 reacts with excess O2, using the following equation. C3H8(g) + O2(g)  CO2(g) + H2O(g)

3. Relating Moles to Molecules
Balance the following chemical equation:
NO(g) + H2(g)  N2(g) + H2O(l)
In terms of molecules,
In terms of moles,

4. Why moles and not molecules?
Moles are macroscopic
Can be measured out by
Converting moles to grams .

5. Predict the products, balance the following equation and give the meaning of the equation in terms of numbers of molecules and moles of molecules
CH4(l) + CO2(g) 

6. Using mole ratios 1. Determine the mole ratio of CO2 to C3H8
2. Determine how many moles of CO2 can be formed from 2 mol of C3H8:
C3H8(g) + 5O2(g)  3CO2(g) + 4H2O

7. MnO2(s) + Al(s)  Mn(s) + Al2O3(s)
Balance, and give the following mole ratios for each reaction: reactant 1 to reactant 2, and reactant 1 to product 2
MnO2(s) + Al(s)  Mn(s) + Al2O3(s)
B2O3(s) + CaF2(s)  BF3(g) + CaO(s)
C6H6(g) + H2(g)  C6H12(g)

8. C3H8(g) + 5 O2(g)  3CO2(g) + 4H2O(g)
One more together…
Look at the following balanced chemical equation. How many moles of carbon dioxide can be formed with 4.70 mol of C3H8 and excess oxygen gas?
C3H8(g) + 5 O2(g)  3CO2(g) + 4H2O(g)

9. Practice time!
How many moles of sulfur dioxide gas can be produced from 5 moles of oxygen gas?
How many moles of oxygen gas are required to react with 5.6 moles of hydrogen sulfide?
H2S(g) + O2(g)  SO2(g) + H2O(l)

10. Dealing in measurable quantities- grams
To use mole ratios you must be in moles
If going g  g, must go gmolg
This is because the mole ratios (found from coefficients) are valid only for moles

11. A stepwise look at using mole ratios
Write the chemical equation and balance it
Figure out what you know and what you need to find out
Convert to moles if nec., use the proper mole ratio, set up and solve

12. Practicing Together
How many grams of oxygen gas would be formed if 5.80 g of bismuth(III) oxide reacted completely?
Bi2O3(s)  Bi(s) + O2(g)

13. Practice together
How many grams of NaHCO3 (baking soda) are required to exactly neutralize 5.02 g of pure HCl?

14. Vocab time Stoichiometry- (stoy-key-ah-meh-tree)
the process of using a bal. chemical equation to calculate relative masses of reactants and products involved in a rxn

15. Groupwork time! Be ready to work hard

16. Grab a new partner
Calc. the mass of carbon dioxide as required to react w/a solution containing 10.0 g sodium hydroxide.
Calc. the mass of sodium carbonate produced when 10.9 g of sodium hydroxide reacts with excess carbon dioxide.
NaOH(aq) + CO2(g)  Na2CO3(g) + H2O(l)

17. Workspace: Partner Work (8.3)

18. Partner Work Continued
Na(s) + Cl2(g) 
Predict the products and balance the equation above
How much product (g) will be formed from 24.7 g of Na?
How much chlorine gas is required to react with the mass of Na from #2?

19. Workspace: Partner Work (8.3)

20. Limiting Reagent
Limiting reagent- the reactant that limits the amount of product that can be formed when reactants are combined in non-stoich. quantities

21. Problem time- Deter. a LR
If you have 2.50 x 104 g of nitrogen gas reacting with 5.00 x 103 g of hydrogen gas to form ammonia (gas) which reactant will be the limiting reagent?

22. Steps for LR problems Steps: Balance eq’n convert gmol for reactants
Key Phrases: limiting reagent/reactant, how much ___ will form, which reagent in excess
Steps:
Balance eq’n
convert gmol for reactants
Det. Moles need using molar ratios and compare w/moles have
Using mol of limiting reagent, calc. moles of desired product
For prod., convert molg

23. One more together
Suppose that exactly 5.00 g of each reactant is taken for the chemical equation below. Determine the LR and calculate what mass of each product is expected.
MnO2(s) + H2SO4(l)  Mn(SO4)2(s) + H2O(l)

25. Try this with a partner/trio!
Suppose that 1.00 g of Zn metal reacts with 1.00 grams of aqueous hydrochloric acid to form aqueous zinc (II) chloride and hydrogen gas. Calculate the mass of hydrogen gas that should form.

27. Vocabulary Time!
Draw a diagram that illustrates the differences between percent yield, theoretical yield, and experimental yield.

28. Give the formula for percent yield:

29. Finish the lab!
Get your cooled beaker from the chem. projects room, and finish your lab. Please remember to clean your beaker afterwards and hang to dry. Use a test tube cleaner and a little soap to scrub off the sharpie label.

30. List keyword phrases that tell you that you must first find the LR in the problem:

31. List keyword phrases that indicate that it is unnecessary to determine the LR:

32. What mass of silicon carbide should result when 1
What mass of silicon carbide should result when 1.0 kg of pure sand is heated with an excess of carbon?
Given:
Find:
Plan:
SiO2(s) + C(s)  CO(g) + SiC(s)
If the actual (experimental) yield of the silicon carbide is 6.13 kg, what is the percent yield?

33. Example together
A student completely reacts 5.00g of magnesium with an excess of oxygen to produce magnesium oxide.  Analysis reveals 8.10 g of magnesium oxide.  What is the student's percent yield?

34. Quiz S. 9.5 Define theoretical yield.
What is percent yield? You can describe or give a formula for this one. Either is fine.