Yes, more math!!
Plan of the Day
 Review
 Balancing equations
 Mass to mass problems
 Introduce Mass to Volume Equations
 Introduce Volume to Volume Equations
 HW Time
Plan of the Day 4/15/11
 Review Molar Volume Lab
 Recalculations
 Review Ch 10 Test
 In groups, work through each problem
 Take notes as needed
 Questions???
 Ch 10 Retest next class – best score
 Current HW Questions???
Plan of the Day 4/18/11
 Review Molar Volume Lab
 Recalculations
 Review Ch 10 Test
 In groups, work through each problem
 Take notes as needed
 Questions???
 Ch 10 Retest next class – best score
 Current HW Questions???
Plan of the Day 4/20/11
 Ch 10 Retest Today – for best score
 Any last minute Questions?
 Continue w/ Ch 11 & 12 HW
 Mass/Volume Lab 4/22/11
 Chapter 11 & 12 Test 4/26/11
Plan of the Day 4/21/11
 Mass/Volume Lab
 Conduct, calculate & turn in
 Continue w/ Ch 11 & 12 HW
Chapter 11 & 12 Test 4/25/11
& HW Quiz
Plan of the Day 4/22/11
 Mass/Volume Lab
 Conduct, calculate & turn in
 Continue w/ Ch 11 & 12 HW
 Ch 11 #1-11 & 15
 Ch 12 #1-10
Chapter 11 & 12 Test 4/26/11
& HW Quiz
Balancing Equations
 What do you remember? (lets just brainstorm!)
 What do the balanced equations tell you?
 Why? Law of Conservation—who can explain?
 How do Chemists use this relationship?
 Like a recipe!
 Let’s try one: Ca + H2O  Ca(OH)2 + H2
 Ca + 2 H2O  Ca(OH)2 + H2
 And another : C2H6 + O2  CO2 + H2O
 2C2H6 + 7O2  4 CO2 + 6 H2O
Balancing Equations
 Video’s?
 http://www.youtube.com/watch?v=RnGu3xO2h74&play
next_from=TL&videos=h7PQ10ClYzI
Mass to Mass Example 1

Given a certain amount of a reactant how do we find
the mass of a certain product?
2C2H6 + 7O2  4CO2 + 6 H2O
How much ethane would it take to get 20 grams of
carbon dioxide?


1.
2.
3.
Balance Equation
Identify known & unknown
Equation to solve
a. Mass of known to moles of known
b. Moles known to moles unknown
c. Moles unknown to mass unknown Balance Equation
• Using
molecular
mass g/mol
Mass
Moles
• Using the ratio in a
balanced equation
allows us to convert
from one substance
to another.
• Using
molecular
mass g/mol
Mass
Mass to Mass Example 2
 How many grams of glucose form when 88.0 g of
CO2 reacts?
CO2 + H20  C6H12O6 + 6 O2
 First what are the steps? Using words write them
down.
 Now what purpose does each step serve? Using
words!
 Share with the class!
 Calculate
 Answer is 60.0g C6 H12O6
Mass to Volume…
Blue Book Ch. 11
 What is the relationship between
moles and volume with gases?
 How do we get from volume to mass
and vice versa?
 What are the steps?
Mass to Volume cont..
Moles
Mass
Moles
Balance Equation
2. Identify known & unknown
3. Mass to Moles (known)
Volume 4. Moles (known) to Moles
(unknown)
5. Moles (unknown) to
Volume of unknown (22.4
dm3 = 1 mole)
1.
Ch 11 Mass to Volume Example 1
 Calculate the volume of oxygen produced at STP by the
decomposition of 10.0 g of potassium chlorate, KClO3.
KClO3  KCl + O2
 Hint





Balance the equation
I.D. known & unknown
Convert the grams to moles
Convert moles of KClO3 to moles of O2
Convert moles of oxygen to volume using our handy 22.4
dm3 = 1 mol of any gas @STP!
 Answer: 2.74 dm3 O2
Ch 11 Mass to Volume Example 2
 How many cubic centimeters of hydrogen are
produced by the reaction of .750 grams of sodium
metal with excess water?
Na + H2O  NaOH + H2
 Hint
Balance the equation
Convert the sodium to moles
Convert moles of sodium to moles of hydrogen
Convert moles of hydrogen to volume using our handy
22.4 L = 1 mol of any gas!
 Throw in a cm to dm conversion




 Answer: 365 cm3
Ch 11 Mass to Volume Example 3
 Al reacts with HCl to produce aluminum chloride and
hydrogen gas. How many dm3 of hydrogen at STP are
produced if Al reacts with an HCl solution which has a
mass of 80.0g and contains 70.0% water?
Al + HCl  AlCl3 + H2
 If 80.0 g of a solution of HCl is 70% water then it is
30% pure HCl, use part to whole:
30g pure HCl/100 g solution of HCL
 ANSWER: 7.36dm3 H2
Ch 11 Mass to Volume Example 4
 How many grams of ammonium sulfate must react with
excess sodium hydroxide to produce 400 cm3 of
ammonia measured at 27oC and 98.0 kPa?
(NH4)2SO4 + NaOH  Na2SO4 + NH3 + H2O
 Answer: 1.04 g (NH4)2SO4
Ch. 12 Volume to Volume: How do
chemists
convert
volume
to
volume???
 First Step?
 Balance the Equation
 Second Step?
 ID known & unknown
 Third Step
 Volume of known to Moles
of known
 Fourth Step?
 Moles of known to moles
of unknown
 Next?
 Moles of unknown to
volume of unknown.
Balance
the Eqn
Volume
Moles
(Ratio)
Volume
Volume to Volume Example 4

If 6.00 dm3 of oxygen are available to burn
carbon disulfide, how many dm3 (liters) of
carbon dioxide are produced? The products of
the combustion of carbon disulfide are carbon
dioxide and sulfur dioxide.
CS2 + O2  CO2 + SO2
1.
2.
3.

Volume to Mole (known)
Mole (known) to Mole (unknown)
Mole (unknown) to Volume (unknown)
2.0 dm3 CO2
Anybody see a shortcut??
 All gases
 So…

6.00dm3

1 dm3 CO2
3dm3 O2
= 2.oo dm3 CO2
 the known volume can be multiplied by the mole ratio to
find unknown volume (see p. 120 in Blue Book)
 CAREFUL… only if the gases are measured under the same
conditions of temperature & pressure
Chapter 12 – example 3
When a hydrocarbon such as ethylene burns complete in
oxygen, the products are carbon dioxide and water.
Calculate the liters of air required to burn completely
15.0 dm3 of ethylene gas, C2H4, measured at STP. Assume
that air contains 21.0% oxygen by volume.
C2H4 + O2  CO2 + H2O
*Hint: the answer needs to be stated in dm3 of air – but
only oxygen in the air reacts with ethylene gas.
Answer: 214 dm3 of air
Ch 12 Volume to Volume Example 5

How many liters (dm3) of air measured at 98.5
kPa and 100o C are required to produce 200dm 3
of CO2 measured at the same pressure and 20o
C? Assume that air contains 21% oxygen by
volume and that the CO2 is being produced from
CO.
CO + O2  CO2
Balance Equation
2. Old/New Chart to find missing volume
3. Conversions?
1.


1 dm3 O2 = 2 dm3 CO2
21 dm3 O2 = 100 dm3 air
4. Put it all together
ANSWER: 606 dm3 air
Chapter 11 Mass-Volume HW
#1-11 & 15
Chapter 12 Volume-Volume HW
#1-10
*Chapter 11 & 12 Test: 4/19 & 4/20*
(B-day)
(A-day)