Chemical Reactions

1
Chemical Reactions

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• Mr. Chan
• Northwestern University

2
Today (Day 84)

• (0-5) Warmup/Review
• Chemical formula of
• Cobalt(II)chloride
• Diphosphorus pentoxide
• (5-15) Discuss Final Exams, Grades
• (15-20) 1st semester evals changes
• New Syllabus, New Quarter Binder/Notebook Check
• (20-35) Writing Chemical Equations
• (35-40) HW Head Start Peer Group Choices

3
Writing Chemical Equations

• Chemical Reactions all around us
• Examples
• All have Reactants yielding Products
• Chemical Equations
• Atoms are rearranged bonds broken, bonds formed
• NO loss of mass Conservation of Mass
• Word Equations
• Samples
• decomposition of hydrogen peroxide
• Iron oxygen yields rust (ironIIIoxide)
• Burning gas in lab methane oxygen
• Parts of a Chemical Equation
• Reactants on left side
• Products on right side
• Physical States of Substances
• Solid, liquid, gas, aqueous, catalyst
• Skeleton Equations
• Base equation does not indicate relative
  amounts
• Get the chemical formulas of reactants and
  products correct first.

4
Today (Day 85/86)

• (0-10) Warmup/Review Chemical Equations
• Skeleton Equation chlorine gas plus aqueous
  sodium iodide yields aqueous sodium chloride and
  iodine vapor.
• H2SO4(aq) BaCl2(aq) arrow BaSO4(s) HCl(aq)
• (10-15) Homework Questions
• (15-20) New Lab Groups/procedures
• (20-30) PreLab
• Objectives
• Lab Techniques
• (30-43, 0-43) Lab

5
Today (Day 86/85)

• Warmup/Review (0-10)
• Homework Questions (10-15)
• (0-30) Finish Lab
• (30-43) Balancing Equations (15-35)
• HW Head Start (35-43)

6
Balancing Chemical Equations

• Each side of equation has the same number of
  atoms of each element
• Obeys law of conservation of mass
• Use coefficients in front of symbols to balance
  equation

7
Rules for Balancing Equations

• 1) Write reactants and products
• 2) Must have correct chemical formulas
• Watch out especially for ionic compounds with
  correct charges
• 3) Count number of atoms
• Keep polyatomic ions together if unchanged on
  both sides
• 4) Balance by changing the coefficients
• Save Oxygen and Hydrogen usually for last
• 5) Check answer
• Youll know if you made a mistake
• 6) Make sure that you have the lowest ratio of
  coefficients
• Examples
• PbO2 yields PbO O2
• P O2 yields P4O10
• NaCl H2SO4 yields Na2SO4 HCl
• Al CuSO4 yields Al2(SO4)3 Cu
• Words to Equations
• Carbon oxygen arrow carbon monoxide
• Practice 3-8

8
Today (Day 87)

• Finish Lab (0-30)
• (0-10) Warmup/Review
• Counting Atoms Al2(SO4)3
• Balancing Equations
• Hydrogen sulfur arrow hydrogen sulfide
• Sodium water arrow sodium hydroxide hydrogen
• (10-15) Homework Questions (30-35)
• (15-43) ACT Practice
• (0-20) New Jobs, Clock Buddies, Review/discuss
  lab, Finish Lab
• (20-43) Continue balancing equations w/Peer
  Groups, HW catchup

9
Today (Day 88)

• (0-10) Homework Questions
• (10-43) Types of Reactions Stations Activity

10
Today (Day 89)

• Quiz (0-20)
• Finish Types of Reactions Stations (20-43)

11
Today (Day 90)

• (0-10) Warmup/Review
• Balancing Equation Al O2 yields Al2O3
• Write/balance carbon plus oxygen yields carbon
  monoxide
• What are patterns in these reactions?
• (10-15) Discuss Quiz
• (15-43) Reactions Stations Activity
• (0-30) Classifying Types of Reactions
• Science Information Day
• (30-43) Predicting Products of a Reaction
• General Equations
• Warmup/Review
• HW Questions
• Finish Lab
• Discuss Lab

12
Identifying Types of Reactions

• Want to start recognizing patterns in chemical
  reactions
• 1) Combination (synthesis) reactions
• 2 reactants forming 1 product
• Ex. 2 K Cl2 yields 2KCl
• Demo
• 2) Decomposition reactions
• 1 substance breaks down to form 2 products
• Ex. H2O electricity yields H2 O2
• Demo
• 3) Single Replacement Reactions
• 1 element replaces another element
• Activity Series of Metals (Handout)
• Ex. Zn H2SO4 yields ZnSO4 H2
• Demo
• 4) Double Replacement Reactions
• Exchange of positive ions between two compounds
• Precipitate formed, Gas formed, or Water or
  molecular component formed
• Ex. Na2S Cd(NO3)2 yields CdS 2NaNO3
• Demo

13
Today (Day 91)

• (0-10) Warmup/Review
• Predict the Products for Single Replacement
  Reactions
• Ag(s) KNO3 (aq)
• Zn(s) AgNO3(aq)
• Introduce Activity Series
• HCl(aq) Ca(OH)2 (aq)
• Ag2SO4(aq) AlCl3(aq)
• (10-20) Homework Questions
• (20-43) Hollow Penny Lab
• Net Ionic Equations (20-43)
• Whats Really Going On? (0-30)
• Discuss Lab (30-43)
• ACT Passage? (0-10)

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Predicting Products

• General Equations
• Synthesis AB yields AB
• Decomposition AB yields A B
• Single Replacement A BC yields AC B
• Double Replacement AB CD yields AD CB
• Combustion AB O2 yields AO BO
• Examples (overhead)

15
Today (Day 92)

• (0-5) Warmup/Review
• (5-15) Discuss HW/Questions (0-10)
• (15-30) Types of Reactions w/Demos
• Double Replacement Reactions
• (30-43, 0-20) Hollow Penny (10-20)
• (20-43) Quiz (20-43)

16
Today (Day 93)

• (0-15) Hollow Penny
• (15-30) Hollow Penny Debrief
• (0-15) Review/Discuss QUIZ/Announce Extra Credit
  (30-43)
• (15-43) Whats Really Going On? (0-20)
• Debrief/Work (20-43)

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Ionic Equations (HONORS ONLY)

• Double Replacement Reactions
• Aqueous substances dissolved, separate into ions
• Complete ionic equation
• Show all free ions
• Spectator ions
• Appear on both sides of the equation
• Net Ionic Equation
• Cancel all of the spectator ions
• Make sure ionic charge is balanced
• Practice
• Zn HCl yields ZnCl2 H2
• Pb(ClO4)2 NaI yields PbI2 NaClO4

18
Predicting Products of Double Replacement
Reactions

• Solubility Rules
• Table 8.3
• Reactants 2 ionic compounds (solutions)
• Precipitates (insoluble)
• No Reaction (all of products are soluble)
• Practice 25-27

19
Today (Day 94)

• Review
• Summarizer Relay Summaries?

20
Today (Day 95)

• Test
• Check Syllabus
• Introduce Chemical Equations Animation Project

21
Today (Day 96-98)

• Equations Animations Computer Lab

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