30 Nov. 2010
Law of Conservation of Mass
Objective: SWBAT demonstrate the law
of conservation of mass and show it
symbolically through the use of
coefficients in a balanced chemical
equation.
 Do now: How many atoms of each
element? (This is not multiple choice!)
a) NaNO3 b) Mg(NO3)2 c) 2H2O

Agenda
Do now
II. Law of Conservation of Mass Notes
III. Practice Problems
IV. Demonstration
V. Balancing Equations Examples
VI. Practice problems
Homework: Week 13 #1-15: Weds.
Lab report 1st draft: Fri.
I.
Announcements
Did you miss the test on Wednesday?
 Take it after school TODAY, or come see
me to make other arrangements.

Law of Conservation of
Mass
Big Picture
If 5.00 grams of oxygen are reacted with
5.00 grams of hydrogen, what mass of
water is formed?
• Is there any oxygen or hydrogen left over?
• Which one?
• How much?
Review of writing chemical equations
Remember:
 (g) = gas (l) = liquid (s) = solid
 (aq) = aqueous
 Must use rules for naming/writing
formulas
 Ionic compounds – balance charges, NO
prefixes
 Covalent compounds – use prefixes

Information from Chemical Equations


To produce fertilizers, Nitrogen gas is
combined with Hydrogen gas to produce
Nitrogen trihydride (ammonia).
N2(g) + H2(g)  NH3(g)
Information from Chemical Equations
Making fertilizer uses a lot of energy and a
lot of raw materials
 Efficiency is key!!
 How can knowledge about
chemical reactions make
This process as efficient
as possible?

1.
2.
CS2(l) + O2(g)  CO2(g) + SO2(g)
Liquid carbon disulfide reacts with
oxygen gas to produce carbon dioxide gas
and sulfur dioxide gas.
Solid aluminum reacts with a solution of
zinc chloride to produce solid zinc and a
solution of aluminum chloride.
Al(s) + ZnCl2(aq)  Zn(s) + AlCl3(aq)
The Law of Conservation of Mass
In a chemical reaction, matter is never
created or destroyed.
 The number of atoms and the mass of the
reactants must be equal to the number of
atoms and the mass of the products.

Demonstration
Solid sodium bicarbonate reacts with a
solution of acetic acid to produce…
 NaHCO3(s) + CH3COOH(aq) 
CO2(g) + H2O(l) + NaCO3(aq)
Initial mass:
Final mass:
Thoughts? Why doesn’t this reaction satisfy
(obey) the law of conservation of mass?


What could we do to make it satisfy the
law of conservation of mass?
More examples:
Law of Conservation of Mass




CS2(l) + O2(g)  CO2(g) + SO2(g)
If I reacted 5 grams of CS2 with 5 grams of O2,
and the reaction produced 2 grams of CO2, how
many grams of SO2 must have been produced?
If my products had a total mass of 20 grams,
how many grams of reactants must I have
started with?
If I reacted 3 grams of CS2 with an unknown
number of grams of O2 and produced a total of
4 grams of products, what was the mass of the
O2?
A: 30 Nov. 2010



Take Out Homework: Week 13 #1-8
Objective: SWBAT use coefficients to
balance equations, satisfying the Law of
Conservation of Mass
Do now: a) Write the formula equation:
Hydrogen gas reacts with fluorine gas to
produce hydrogen fluoride gas.
b) If 3 grams of hydrogen gas is reacted with
2 grams of fluorine gas, how many grams of
hydrogen fluoride gas are produced?
Agenda
Do now, Homework solutions
II. Balancing Equations Examples
III. Practice Problems
Homework: Week 13 #9-15
Lab report: Friday
I.
How do we show, in a chemical equation,
that the law of conservation of mass is
being obeyed?
 The law of conservation of mass must be
satisfied by equalizing the number of
atoms on the reactant and the product
sides.
 Use coefficients to show how many
molecules of each compound.

Balancing Equations
H2(g)


H2(g)
+ F2(g) 
HF(g)
+ F2(g)  2 HF(g)


H2O(l) 
H2(g) +
2H2O(l)  2H2(g) +
O2(g)
O2(g)
Balancing Chemical Equations
Ca(s) +


8Ca(s) +
S8(s)
S8(s)

CaS(s)
 8CaS(s)


Zn(s) + HCl(aq)  ZnCl2(aq) + H2(g)
Zn(s) +2HCl(aq)  ZnCl2(aq) + H2(g)
Rules for balancing an equation
1. Only change the coefficients that appear
in front of an element or compound
2. Never change any subscripts in a formula
3. Coefficients should be written as the lowest
possible ratios
4. Begin by balancing elements that appear
ONLY once on each side of the equation
A: 1 Dec. 2010
Take Out Homework: Week 13 #9-12
Objective: SWBAT balance chemical
equations and model the law of
conservation of mass.
Do now: Count the number of atoms of
each element: 5Mg(NO3)2
Agenda
Do now, homework solutions
II. More balancing equations
III. Paperclip bonding mini-lab
IV. Mole ratios
Homework: Finish Mini-Lab Handout: Thurs.
Lab Report: Fri.
Read “Mass and Mole Relationships” lab and
do pre-lab (p. 2)
I.
C: 1 Dec. 2010
Take Out Homework: Week 13 #1-15
Objective: SWBAT balance chemical
equations and model the law of
conservation of mass.
Do now: Count the number of atoms of
each element: 5Mg(NO3)2
Agenda
Do now, homework solutions
II. More balancing equations
Homework: Week 13 Homework #16-23
Lab Report: Fri.
I.
Examples
__CaCO3 + __HCl  __CaCl2 + __CO2 + __H2O
__H2S + __O2  __SO2 + __H2O
__CaO + __HNO3  __Ca(NO3)2 + __H2O
__Fe(OH)3  __Fe2O3 + __H2O
Balancing Chemical Equations
5.
__CaO + __HNO3  __Ca(NO3)2 + __H2O
__Fe(OH)3  __Fe2O3 + __H2O
__ZnS + __ O2  __ ZnO + __ SO2
__ Ag3PO4 + __KBr  __K3PO4 + __ AgBr
__ H2SO3 + __O2  __ H2SO4
6.
__Na2SO4 + __Fe(NO3)3  __NaNO3 + __Fe2(SO4)3
7.
__ AgNO3 + __CaCl2  __AgCl + __Ca(NO3)2
1.
2.
3.
4.
Na2O2
+
H2O 
NaOH
+
O2
2Na2O2
+
2H2O 
4NaOH
+
O2
KClO3

KCl +
KClO4
4KClO3

KCl +
3KClO4
CaCl2 +
Fe2(SO4)3 
CaSO4 +
FeCl3
3CaCl2 + Fe2(SO4)3  3CaSO4 + 2FeCl3
Al2O3 +
HCl 
AlCl3 +
H2O
Al2O3 +
6HCl 
2AlCl3 +
3H2O
AgNO3 +
CaCl2 
AgCl +
Ca(NO3)2
2AgNO3 + CaCl2 
2AgCl + Ca(NO3)2
Na2SO4 + Fe(NO3)3  NaNO3 + Fe2(SO4)3
3Na2SO4 + 2Fe(NO3)3  6NaNO3 + Fe2(SO4)3
3Na2SO4 + 2Fe(NO3)3  6NaNO3 + Fe2(SO4)3
C12H22O11 +
O2 
CO2 +
H2O
C12H22O11 +
12O2  12CO2 +
11H2O
BaCl2 +
(NH4)2CO3  BaCO3 +
NH4Cl
BaCl2 + (NH4)2CO3  BaCO3 + 2NH4Cl

Liquid silicon tetrachloride reacts with
liquid water to produce solid silicon
dioxide and a solution of hydrochloric
acid.

SiCl4(l) + 2H2O(l)  SiO2(s) + 4HCl(aq)

Nitrogen gas reacts with oxygen gas and
water to produce a solution of hydrogen
nitrate.

2N2(g) + 5O2(g) 2H2O(l)  4HNO3(aq)
KOH +
Cl2 
KCl +
KClO3 +
H2O
6KOH + 3Cl2  5KCl +
KClO3 +
3H2O
C: 3 Dec. 2010
Take Out Homework: Week 13 #13-23
 Objective: SWBAT model the law of
conservation of mass and use mole ratios
to relate moles of reactants and products
in a reaction.
 Do now: Balance the following equation:
__ZnO(s) + __C(s)  __Zn(s) + __CO2(g)

Agenda
Do now, homework solutions
II. Paperclip Lab
III. Mole ratios
IV. Using mole ratios examples
V. Practice Problems
Homework: Finish Paperclip mini lab p.3-4
I.
Chemical Bonding Paperclip Minilab
Work with your partner
 Designate one color paperclip as
hydrogen, one as oxygen and one as
carbon. Record these choices.
 Follow the directions EXACTLY, and
record information in the tables.
 When you finish, complete page 3.

O O
O O
O O
O O
O O
O O
H H
H H
H H
H H
H H
H H
O
CC
CC H
H
CC C
CHC
H
C
H
H
C
O
O
O
O
H
H
O
H
H
O
C
H
H
O
O
O
O
O
Mole Ratios in Chemical
Equations
Why do we balance chemical equations?
 Now that we can balance them, what can
the coefficients tell us?
 Use coefficients to form mole ratios to use
as conversion factors!!

Coefficients indicate relative numbers of
moles or molecules of reactants and
products.
 H2(g) + Cl2(g)  2HCl(g)
 One mole of hydrogen gas reacts with one
mole of chlorine gas to yield two moles of
hydrogen chloride gas. OR:
 One molecule of hydrogen gas reacts with
one molecule of chlorine gas to yield two
molecules of hydrogen chloride gas.

H2(g) + Cl2(g)  2HCl(g)
H
H
H
H
Cl
Cl
Cl
Cl
2ZnO(s) + C(s)  2Zn(s) + CO2(g)
Zn
C
Zn
O
O
C
Zn
How many moles of zinc oxide?
 How many moles of carbon?
 How many moles of solid zinc?
 How many moles of carbon dioxide?

O
O
Zn
Na2O(s) + 2CO2(g) + H2O(g)  2NaHCO3(s)
How many moles of sodium oxide?
 How many moles of carbon dioxide?
 How many moles of water vapor?
 How many moles of sodium hydrogen
carbonate?

2Al(s) + 3ZnCl2(aq)  3Zn(s) + 2AlCl3(aq)
How many molecules of aluminum?
 How many molecules of zinc chloride?
 How many molecules of zinc?
 How many molecules of aluminum
chloride?

Mole/Molecule Ratios

H2(g) + Cl2(g)  2HCl(g)
2H2O(l)  2H2(g) + O2(g)
How many moles of water?
 How many moles of oxygen gas?
 Mole ratio of water to hydrogen.
 Mole ratio of hydrogen to oxygen.
 Mole ratio of oxygen to hydrogen.
 Mole ratio of hydrogen to oxygen.

CS2(l) + 3O2(g)  CO2(g) + 2SO2(g)
1.
2.
3.
4.
5.
6.
7.
How many moles of oxygen gas?
How many moles of carbon dioxide gas?
Mole ratio of oxygen to carbon dioxide.
Mole ratio of carbon disulfide to oxygen.
Mole ratio of carbon dioxide to sulfur dioxide.
Mole ratio of carbon disulfide to sulfur
dioxide.
Mole ratio of carbon dioxide to oxygen.
4Fe(s) + 3O2(g)  2Fe2O3(s)
1.
2.
3.
4.
5.
6.
Molecule ratio of iron to oxygen gas.
Molecule ratio of oxygen gas to iron (III)
oxide.
Molecule ratio of iron (III) oxide to iron.
Molecule ratio of oxygen gas to iron.
How many molecules of iron?
How many molecules of iron (III) oxide?
C: 8 Dec. 2010
Take Out Homework: Paperclip
MiniLab
 Objective: SWBAT calculate mole
relationships for chemical reactions.
 Do now: Balance the following equation:
__Fe(s) + __O2(g)  __Fe2O3(s)

SWBAT calculate mole relationships for chemical reactions.
Agenda
Do now, homework solutions
II. Mole relationships examples
III. Practice Problems
Homework: Finish Week 13 Homework:
Tues
Quiz: Tues!
I.
4Fe(s) + 3O2(g)  2Fe2O3(s)
Write all possible mole ratios for this
equation.
SWBAT calculate mole relationships for chemical reactions.

Now that you can write mole ratios, we
can use them to relate numbers of moles
or molecules of any reactant or product to
any other reactant or product.
SWBAT calculate mole relationships for chemical reactions.
4Fe(s) + 3O2(g)  2Fe2O3(s)
1.
2.
3.
4.
How many moles of oxygen gas react with
4 moles of solid iron?
How many moles of iron (III) oxide are
produced by the reaction of 3 moles of
oxygen gas?
How many moles of solid iron are
required to react with 3 moles of oxygen
gas?
How many molecules of iron (III) oxide
are produced by the reaction of 4
molecules of solid iron?
SWBAT calculate mole relationships for chemical reactions.
4Fe(s) + 3O2(g)  2Fe2O3(s)
5.
6.
7.
8.
How many moles of O2 react with 8
moles of Fe?
How many moles of Fe2O3 react with
2 moles of Fe?
How many moles of Fe react with 12
moles of O2?
How many moles of O2 react with 16
moles of Fe?
SWBAT calculate mole relationships for chemical reactions.

What if more than simple math is
involved?
SWBAT calculate mole relationships for chemical reactions.
4Fe(s) + 3O2(g)  2Fe2O3(s)
1.
2.
3.
4.
How many moles of O2 react with 10
moles of Fe?
How many moles of Fe2O3 are
produced by the reaction of 20.0
moles of O2?
How many moles of Fe react with 1.2
moles of O2?
How many moles of Fe are required to
produce 7.0 moles of Fe2O3?
SWBAT calculate mole relationships for chemical reactions.
4Fe(s) + 3O2(g)  2Fe2O3(s)
5.
6.
7.
8.
How many moles of O2 react with 15
moles of Fe?
How many moles of Fe2O3 are
produced by the reaction of 8.0 moles
of O2?
How many moles of Fe react with 1.8
moles of O2?
How many moles of Fe are required to
produce 13.0 moles of Fe2O3?
SWBAT calculate mole relationships for chemical reactions.
4Fe(s) + 3O2(g)  2Fe2O3(s)
1.
2.
3.
4.
How many moles of oxygen gas react with
2 moles of solid iron?
How many moles of iron (III) oxide are
produced by the reaction of 1.0 mole of
oxygen gas?
How many moles of oxygen gas are
required to produce 0.35 moles of iron
(III) oxide?
How many moles of solid iron are
required to produce 0.5 moles of iron
(III) oxide?
SWBAT calculate mole relationships for chemical reactions.
4Fe(s) + 3O2(g)  2Fe2O3(s)
1.
2.
3.
4.
How many moles of oxygen gas react with
10.5 moles of solid iron?
How many moles of iron (III) oxide are
produced by the reaction of 2.0 mole of
oxygen gas?
How many moles of oxygen gas are
required to produce 0.75 moles of iron
(III) oxide?
How many moles of solid iron are
required to produce 1.5 moles of iron (III)
oxide?
SWBAT calculate mole relationships for chemical reactions.
Homework
Finish Week 13 Homework
 Quiz Tomorrow!
 Writing and balancing equations
 Law of Conservation of Mass
 Mole Ratios
 We will review tomorrow before the quiz.

SWBAT calculate mole relationships for chemical reactions.
A: 3 Dec. 2010
Take Out Homework: Paperclip Mini
Lab AND Lab
 Objective: SWBAT convert between
moles of reactants and products in a
balanced equation.
 Do now: Write all six mole ratios for the
reaction, with units:
4Fe(s) + 3O2(g)  2Fe2O3(s)

Agenda
Do now, collect homework
II. Moles conversions practice problems
III. Answers
Homework: Finish Week 13 Homework
Quiz Tuesday
I.
With your partner, complete the practice
problems.
 Check your answers on the board, and redo problems you got wrong.
 Trade the problem you wrote with a
classmate. Solve that problem.
 Hand in your worksheet.
 Work on your homework (finish Week 13)

C: 7 Dec. 2010
Take Out Homework: Week 13
 Objective: SWBAT write, balance and
calculate mole relationships for chemical
reactions.
 Do now: State the Law of Conservation of
Mass. Explain how we show the Law of
Conservation of Mass in a chemical
equation.
 Your quiz will be TOMORROW.

C. Agenda
Do now, homework solutions
II. Collect Paperclip Mini-Lab worksheet
III. Practicing Mole Relationships
IV. Unlock the Code Review Activity
V. Pre-lab instructions and calculations
Homework: Finish Unlock the Code
worksheet
Quiz Tomorrow
I.
Moles Review
Complete this worksheet with your
partner.
 Ask me for help if you need it!
 It is due at the end of 1st period.
 Stay in your seat.

Unlock the Code
1.
2.
3.
4.
Carefully answer all four questions on the
worksheet. Show all your work!
The code is the first digit of each answer (if
a balanced chemical equation, the first
coefficient! If no coefficient = 1)
Write the code at the top of the page, and
bring it to me to try the lock.
When you successfully open the lock, you
are finished!
Lab: Friday
Can you show the relationship between
moles and mass of reactants and
compounds experimentally?
 How will your experimental results differ
from your theoretical results?

p. 2 of lab handout
Solid sodium bicarbonate reacts with a
solution of hydrochloric acid to produce
carbon dioxide gas, water and a solution
of sodium chloride.
 The water will be evaporated to leave
behind solid sodium chloride.
 Formula equation?

With your partner
Balance the equation.
 From the balanced equation, record the
number of moles of sodium bicarbonate and
the number of moles of sodium chloride.
 Write a mole ratio.
 Write a paragraph describing the procedure.
 Due Wednesday.

Homework
Finish Unlock the Code Review worksheet
Quiz Tomorrow
A: 7 Dec. 2010
Take Out Homework: Unlock the Code
Worksheet
 Objective: SWBAT what you know about
writing and balancing chemical equations
and mole relationships!
 Do now: Write and balance the formula
equation:
Solid aluminum reacts with oxygen gas to
produce solid aluminum oxide.

Agenda
Do now
II. Quiz!
III. Work on pre-lab: due tomorrow
Homework: Completed pre-lab
I.
When you finish the quiz, turn it over on
your desk.
 Remain silent.
 Work on the pre-lab p. 2, which is due
tomorrow.
 Make sure you have written an excellent
summary of the procedure!

C: 10 Dec. 2010
Take Out: Lab Worksheet (p. 2)
 Objective: SWBAT show empirically the
mole relationships in a chemical reaction.
 Do now:
a) What are the formulas of the three
products produced in this lab?
b) Which product will you be finding the
mass of?

Agenda
Do now
II. Pre-lab
III. Lab!
Lab handout due at the end of the period!
No homework
I.
SWBAT show empirically the mole relationships in a chemical reaction.
Name
Solid reactant
Aqueous reactant
Solid product
Liquid product
Gaseous product
Balanced Equation
Moles of sodium
bicarbonate
Moles of sodium
chloride
ratio of moles of sodium
bicarbonate : moles of
sodium chloride
Formula
In this lab…
Solid sodium bicarbonate reacts with a
solution of hydrochloric acid to form
carbon dioxide gas, water, and a solution of
sodium chloride.
1. Write and balance the chemical equation.
2. Predict mole ratios using the balanced
equation.
3. Compare theoretical mole rations (your
prediction) with experimental mole ratios
(from your experiment’s results)
SWBAT show empirically the mole relationships in a chemical reaction.
Some notes on the lab
Always wear your goggles!
 When massing sodium bicarbonate
(baking soda) any amount between 2 and
2.5 grams is fine! Just carefully record the
initial mass.
 When getting 10 mL of hydrochloric acid,
use the transfer pipet to do so carefully!

SWBAT show empirically the mole relationships in a chemical reaction.
A hot evaporating dish looks the same as a
cold one. Use tongs! Move carefully and
slowly.
 Never mass a hot evaporating dish. Cool
your evaporating dish on the wire gauze.

SWBAT show empirically the mole relationships in a chemical reaction.
When you finish working, clean up all
your equipment.
 Then start working on calculations and
conclusions questions.
 Hand in your worksheet when you finish.

SWBAT show empirically the mole relationships in a chemical reaction.

During “wait time:”
 Answer conclusions questions
 Brainstorm errors and exactly how
they’ll affect your final results (the mole
ratio of NaHCO3 to NaCl)
 Choose one error and write it on the
board, along with exactly how it affects
your results and your mole ratio.
C: 8 Dec. 2010
Take Out Homework: Unlock the Code
Worksheet and Moles Ratios Practice
 Objective: SWBAT what you know about
writing and balancing chemical equations
and mole relationships!
 Do now: Write and balance the formula
equation:
Solid aluminum reacts with oxygen gas to
produce solid aluminum oxide.

Agenda
Do now
II. Quiz!
III. Work on pre-lab: due tomorrow
Homework: Completed pre-lab
I.
SWBAT what you know about writing and balancing chemical equations and mole
relationships!
This period…
When you finish the quiz, turn it over on
your desk.
 Remain silent.
 Work on the pre-lab p. 2, which is due
tomorrow.
 Use information from the paragraph on p.
1 to fill in the chart on the top of p. 2
 For #2 on p. 2, write a summary of the
procedure, in your own words.

SWBAT what you know about writing and balancing chemical equations and mole
Homework
Read p. 1 of the lab handout
 Complete p. 2
