12 14 balancing review
TRANSCRIPT
Launch: 12/14Grab your binder and immediately take a seat!
Place binder paper and a pen/pencil on your desk.
Review Objective #1: I can write balanced chemical equations.
Tonight’s HW: Finish Review Worksheet #1
Launch 12/14
Launch 12/1416.How many grams does 2 moles of soda niter
NaNO3 weigh?
a. 17g
b. 85g
c. 170g
d. 1700g
Launch Answers
Launch Answers16.How many grams does 2 moles of soda niter
NaNO3 weigh?
a. 17g
b. 85g
c. 170g
d. 1700g
Practice Exam Results: B1Our goal = 80%
Our average = 86%
Questions dropped5, 6, 7, 9, 14
Practice Exam Results: B1Our goal = 80%
Our average = 78%
Questions dropped5, 6, 7, 9, 14
Practice Exam Results: B1Our goal = 80%
Our average = 87%
Questions dropped5, 6, 7, 9, 14
Practice Exam Results: B1Our goal = 80%
Our average = 88%
Questions dropped5, 6, 7, 9, 14
AnnouncementsUnit #5 Exam on Thursday
3 days to reviewAsk questions!No copying HW or classwork!
Make-up work is due on Wednesday
Binder check this week
Exam Information30 multiple-choice questions
Balancing equations (6 questions = 20%)The mole (9 questions = 30%)Conversions (15 questions = 50%)
gram mole (6 questions)gram atoms (3 questions)gram gram (6 questions)
3 free response
Review:Balancing Equations
Mr. Heffner12/14/09
CH4 + 2O2 CO2 + 2H2O
What’s a chemical equation?
Reactants Products“turn into”
What’s a chemical equation?
4Fe2(CO3)3
Multiply!8 X Fe12 X C36 X O
CoefficientSubscript
How are equations balanced?
There is a 3-step process for balancing equations:
1.Count the atoms on both sides
2.Change a coefficient & multiply out
3.Check tally (and repeat)
Rule: You can’t change the subscripts!
ExampleBalance the equation,
N2 + H2 NH3
Step #1: Count the atoms on both sides
N2 + H2 NH3
Example
2 X N 2 X H 1 X N3 X H
Unbalanced!
Step #2: Change coefficient & multiply out
N2 + H2 NH3
Example
2 X N 2 X H 1 X N3 X H
2
2 X N6 X H
2X( )
Step #3: Check tally (and repeat)
N2 + H2 NH3
Example
2 X N 2 X H
2
2 X N6 X H
3
6 X H
Still unbalanced!
3X( )
Step #3: Check tally (and repeat)
N2 + H2 NH3
Example
6 X H
2
2 X N6 X H
3
2 X N
Balanced!
Snowman ChallengeDirections:
Send one group member to pick a cardWrite down the equation and #Balance it showing all work (count, coefficient, check)When finished, send one group member to have me
check your answer
Rules: If you pick it, solve itOnly one card at a timeShow your work!Work together
Exit SlipHC2H3O2 + NaHCO3 NaC2H3O2 + H2CO3
� Which of the following correctly identifies all of the reactants in the above chemical equation.� NaC2H3O2
� NaHCO3
� NaC2H3O2 and HC2H3O2
� HC2H3O2 and NaHCO3
Exit Slip2. How many C atoms are there in 3C2H4?
a. 2
b. 3
c. 5
d. 6
Exit SlipH2 + Cl2 HCl
3. Is the above equation balanced?a. No, because H2 has a coefficient of 2.
b. No, because the number of Cl and H atoms are not equal on both sides of the equation.
c. Yes, because the number of H atoms is not equal on both sides.
d. Yes, because there are equal numbers of atoms on both sides of the equation.
Exit Slip4. Which of the following is a balanced equation
for the combustion of ethanol (C2H6O)?
a. C2H5OH + 3O2 CO2 + 2H2O
b. C2H5OH + 3O2 2CO2 + 3H2O
c. C2H5OH + O2 2CO2 + 3H2O
d. C2H5OH + 2O2 3CO2 + 2H2O
Exit Slip__C2H2 + __H2 __CH4
5. When the equation above is completely balanced, the coefficient for H2 would be
a. 1b. 2c. 3d. 4
HomeworkFinish practice questions worksheet