WARM – UP:



Write your homework – leave it to be stamped!
Update your Table of Contents for
today…start a new section for the last section
of chemistry!
Grab a marker off the front counter to grade
your test with & let me know now if you did
not take the test!
Date
Session
#
10/27
10/28
1
Activity
Page
#
Law of Conservation of Mass Notes & Lab
1
Law of Conservation of Mass Homework
2
Annotating a Test Question
 33.
When 2 or more substances
physically combine that will create
____________.
A. An element
B. A compound
C. A mixture
D. A molecule
Annotating a Test Question

35. Mercury is dumped into a lake
and it results in the death of many
species of fish. Which property is this
a result of?
A.
B.
C.
D.
Boiling point
Reactivity with oxygen
Specific heat
Toxicity
Physical & Chemical changes can
change matter, BUT…THE REAL
QUESTION IS:
During those changes, is any
matter created or destroyed?
Law of Conservation of Mass/Matter
Law of Conservation of Mass/MatterMatter cannot be created or destroyed, it
can only change form.
So where does the wood go?
Na
F
NaF
IN OTHER WORDS…
What goes in, must come out!
Open System/Reaction

The container in which the reaction is
performed is open - matter may escape
Closed System/Reaction

The container in which the reaction is
being performed is closed so all of the
matter will be contained – nothing escapes
Dry Ice Demo
Dry Ice = Solid Carbon Dioxide
 Freezing Point of Carbon
-108.4oF or -78oC
 Boiling Point of
-76oF or -57oC
 Formula:
CO2(s)
Dioxide =
Carbon Dioxide =
Is this physical or chemical?
CO2(g)
Watch the demo and write as many
observations as you can!
Dry Ice Demo
 Write
as many observations as you
can!
 Fully explain how this
demonstrates The Law of
Conservation of Mass!
Dry Ice Demo
Observations: (bullet point)
Dry Ice Demo
Fully explain how this demo demonstrates
the Law of Conservation of Mass?
Law of Conservation of Mass (Matter) Lab
Investigation Roles





Group Leader – Reading the directions and making sure
the group is following directions accurately and
completing all parts of the lab
Supply Manager – Gets, returns & cleans supplies
Measurement Technician – gets and returns the scale
balance and is responsible for accurate mass
measurements
Data Discussion Technician – makes sure the group
records the mass data before and after the experiment,
AND everyone has an explanation for THE TEACHER
DEMO, STUDENT LAB & COMPARE & CONTRAST
ONE LAB GUIDE WILL BE PICKED FOR THE GROUP GRADE
Law of Conservation of Mass (Matter) Lab
Investigation


Send your supply manager to get the lab kit
and your measurement technician to get the
scale balance.
Group leader, read the directions carefully each
step of the way!!
◦ WARNING: YOUR BALLOON IS ALREADY FULL
OF BAKING SODA, DO NOT TIP IT INTO THE
GRADUATED CYLINDER ACCIDENTALLY!
Law of Conservation of Mass (Matter) Lab
Investigation Clean-Up






Balloons in the garbage
Rinse graduated cylinder thoroughly
Wipe up any spills
Put all items back into your lab kit & put them
on the front counter
Put scale balance back onto the back counter
Make sure every group member has
measurements and ALL parts of the lab guide
are complete
Compare & Contrast
 Again,
the explanation should
state how BOTH experiments
demonstrated the Law of
Conservation of Mass…BUT,
what were the similarities and
differences between them?
WARM – UP:




Write your homework – leave it to be stamped!
Update your Table of Contents for today!
Get your Law of Conservation of Mass
Homework out to be checked – leave it out to
go over it!
Grab your test off the front counter and tape
it into the last section of Chemistry!
Date
Session
#
10/29
10/30
2
Activity
Page
#
Balancing Act Note Guide
3
Balancing Equations Practice
4
Lab Grades…







Use scientific language…stop using the word “it” and
other similar words like “stuff”
Engage in the discussion with YOUR group
The more you discuss & write, the more you think and the
better you can understand – LISTEN to your group
members as well
Be consistent and fully explain, re-read what you wrote –
Does it make sense? Does it contradict with something
you wrote before? Could you add more?
Stop taking one paper from the “smartest” person and
copying it – you won’t know how to answer the question
on your own.
Stop taking someone else’s paper and writing for them
Stop doing the bare minimum…everyone is capable of
getting a 100, but you have to put in the work!
What Does the Law of
Conservation of
Mass/Matter State?
How did the teacher demo or mini lab demonstrate
the Law of Conservation of Mass/Matter?
Compare & Contrast Summary

In both experiments there was a change when two substances
were combined. The dry ice demo demonstrated a physical
change, while the student experiment was a chemical change.
While both experiments had gas bubbles and a temperature
change, they were caused by different types of reactions. The
teacher demo was an example of an open system, while the
student experiment was supposed to represent a closed system.
Even though the demo was an open system, it was closed
temporarily to allow the bubble to fill with gas. This was similar to
how the balloon filled with gas in the experiment even though they
were different types of gases. Both experiments represented
properties, the demo represented boiling point and the student
experiment represented chemical reactivity. Lastly, both
demonstrated the Law of Conservation of Mass because both only
changed form and no matter was created or destroyed.
Compare & Contrast Summary




The demo was cooler
Chemical
Balloon physical
Both bubbled involved air
Na
F
NaF
What goes in must come out
mathematically as well!
Chemical Reactions
Reactants –
Elements OR
compounds
present at the
beginning of a
chemical
reaction
Product –
Compounds
formed by
a chemical
reaction
R
E
A
C
T
A
N
T
S
P
R
O
D
U
C
T
Balancing Chemical Equations

Since matter can neither be created or
destroyed, the mass/amount of
reactants must always equal the
mass/amount of products
Balancing Chemical Equations

Before (Reactants)
Na
F

After (Product)
NaF
Na = 1
Na = 1
F=1
F=1
Na
F
NaF
The arrow indicates that
a change has occurred
Chemical formulas
for elements
Chemical formula
for new compound
2H2 + O2  2H2O
Coefficient
Subscripts
(Reactants)
Subscript
Coefficient
(Products)
What is that little number?
Subscript –
◦ Shows how many atoms of an
element there are.
◦ When there is NO subscript there is
only 1 atom of that element.
O2
NaCl
NH4
K5N4C2
What is that big number in front?
Coefficient –
◦ The number of molecules or
compounds involved in a chemical
reaction
H2
O2
H2
2 H2
O2
2
H2O
So using the coefficient and the subscript you
can find the total number of atoms by…

Multiplying! It is like the distributive
property in math!
3O2
2NH4
5H2O
2Li3F2
4NaCl
2K5N4C2
Rules for Balancing Chemical Equations
1. You CANNOT change subscripts, you can ONLY
change coefficients
2H2 + O2
2H2O
2. It does NOT have to look the same on both
sides, it only has to be balanced mathematically
3. You CANNOT split compounds to write in a
coefficient:
HCl
Rules to Balancing Chemical Equations
4. Only multiply through when it is a compound
because they have already bonded
2H + Cl
NO
2HCl
YES
5. If it is a capital letter, they are each a
separate element:
H, C, O
If it is a capital letter followed by a lower
case letter, it is all one element as well!
Cl, Li, Si
Steps for Balancing Chemical Equations


1. Divide the reactants from the products
with a line.
2. Write down the chemical symbol of each of
the elements on each side of the equation
2 H2 + O
2
2H2O
H=
H=
O=
O=
Steps to Balancing Chemical Equations


3. Using the coefficients and subscripts write
down the number of each element
4. If they are not balanced change the
coefficients using trial and error. You will have
to go back and forth between each side!
2H2 + O2
2H2O
H=4
H=4
O=2
O=2
Lets Practice
P + O2
P 4O6
Lets Practice
Na + O2
Na2O
Lets Practice
Al2O3
Al + O2
Lets Practice
Cl2 + KI
KCl + I2
Balancing Equations Practice



Try the practice problems on your own or
work with your table partner/group…if you
don’t understand please ask someone!
Finish balancing them for homework if you do
not finish in class…you can show me now if
you finish so I can check you off!
If you finish and would like advanced
equations for extra credit, please let me
know!
WARM – UP:




Write your homework – leave it to be stamped!
Update your Table of Contents for today!
Get your Balancing Equations Practice out to
be checked!
Grab the Warm-Up/Note Guide off the front
counter and complete the Warm-Up side only!
Date
11/2 11/3
Session
#
3
Activity
Endothermic Reactions Vs. Exothermic
Reactions
Page
#
5
Balanced or Unbalanced…?
2CH4
+
2O2
2CO2 + 2H2O
Law of Conservation of Mass/Matter
Analyzing Reactions


Some chemical reactions are
ENDOTHERMIC = take “in” or absorb
energy
Some chemical reactions are
EXOTHERMIC = give “out” or produce
energy (heat, light or sound)
How would you tell the difference?
Endothermic Reactions



Energy will be on the reactant side of the
chemical equation
Causes temperature around it to cool (will
feel cold)
EXAMPLES:
◦ Photosynthesis (needs energy from the sun)
◦ Crackable ice packs
Exothermic Reactions



Energy will be on the product side of the
chemical equation
Causes temperature around it to rise
(feels warm/hot)
EXAMPLES:
◦ Cellular Respiration (gives energy to your cells)
◦ Hot hands
◦ Glow sticks
Endo & Exo Lab Investigation Roles




Group Leader – Responsible for reading and
making sure the group is following directions
accurately
Supply Manager – gets and returns supplies
and makes sure they are clean
Discussion Leader – makes sure that all group
members have a detailed explanation for BOTH
investigations!
Speaker – Group member that must share your
explanation/conclusion with the class.
REVIEW
BALANCING
EQUATIONS…What are
the rules and steps to
balancing chemical
equations?
Rules for Balancing Chemical Equations
1. You CANNOT change subscripts, ONLY
coefficients
2H2 + O2
2H2O
2. It does NOT have to look the same on both
sides, it only has to be balanced
3. You CANNOT split compounds to write in a
coefficient:
HCl
Rules to Balancing Chemical Equations
4. Only multiply through when it is a compound
because they have already bonded
2H + Cl
NO
2HCl
YES
5. If it is a capital letter, they are each a
separate element:
H, C, O
If it is a capital letter followed by a lower
case letter, it is all one element:
Cl, Li, Si
Steps for Balancing Chemical Equations


1. Divide the reactants from the products
with a line.
2. Write down the chemical symbol of each of
the elements on each side of the equation
2 H2 + O
2
2H2O
H=
H=
O=
O=
Steps to Balancing Chemical Equations


3. Using the coefficients and subscripts write
down the number of each element
4. If they are not balanced change the
coefficients using trial and error. You will have
to go back and forth between each side!
2 H2 + O
2
2H2O
H=4
H=4
O=2
O=2
Last Chance to Balance


Balance the 5 equations on the sheet – if you
get them correct you will be using the
Chromebooks for the remainder of class to
play chemistry review games.
If you get them incorrect you will move up to
the front counter with me practicing how to
balance equations.
REVIEW



Play the review games listed on the sheet on top
of the Chromebook cart.
You may play with a partner if the game
requires 2 players.
If you get through all of them ONLY then can
you search for alternate CHEMISTRY RELATED
sites/games!!
EXPECTATIONS


I expect you and your partner to play
only what you are supposed to
without being disruptive in any way so
that I can focus on helping the people
who need it!!
When you are working with me you are
expected to complete the equations!!
Equation 1
P + O
P4O10
Equation 2
Cl₂ + NaBr
NaCl +
Br₂
Equation 3
Cs
+
N₂
Cs3N
Equation 4
CuCl₂
+
H₂S
CuS + HCl
Equation 5
Al +
HCl
AlCl₃
+
H₂
Balancing Equations Practice
Homework

Find the Balancing Equations Practice
Homework or take another sheet – we will
work on a few together, and then you can
practice on your own.
Lets Practice: Part D - #1
Na + MgF2
NaF + Mg
Lets Practice: Part D - #2
Cl2 + KI
KCl + I2
IMPORTANT:
Cl = Chlorine
K & I are 2
separate elements
Lets Practice: Part D - #3
HCl + NaOH
NaCl + H2O
Lets Practice: Part D - #4
Na + NaNO3
Na2O + N2
Lets Practice: Part D - #5
PbBr2 + HCl
HBr + PbCl2
REVIEW
Try
6, 7 & 8 on
your own, and
then check the
answer key
Lets Practice: Part D - #6
Na3P + CaF2
NaF + Ca3P2
Lets Practice: Part D - #7
AlBr3 + K
KBr + Al
Lets Practice: Part D - #8
CaF2 + Li2SO4
CaSO4 + LiF