FLASHBACK!

1

• FLASHBACK!
• Chemical Reactions
• Types of Chemical Equations
• Balancing Chemical Equations
• Reaction Rates

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Why should we care about chemical combinations?

• Awareness of basic chemistry can save your life!
• Example mixing certain cleaning solutions can
  produce a poisonous gas
• Ammonia (Windex) Bleach (Clorox)
  Chloroamine (a poisonous gas)
• Chemistry is alive in our everyday life
• Ice Packs, Hot Packs, Air Bags in Cars, Foods

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3
Compounds

• Compounds are groups of elements chemically
  bonded together
• 2 types weve studied
• IONIC bonding where electrons are gained or
  lost
• COVALENT bonding where electrons are shared

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EXOthermic Reactions

• A reaction that releases energy and gives off
  heat/light/sound resulting in a raising of
  temperature
• energy will be with the products side of a
  chemical equations
• Examples glow sticks, fire, lycopodium powder

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ENDOthermic

• A reaction that ABSORBES energy resulting in
  LOWERING of temperature.
• energy will be with the REACTANTS side of a
  chemical equations
• Examples ANTACID WATER, PHOTOSYNTHESIS

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Physical Changes

• Changes in PHYSICAL properties
• Melting
• Boiling
• Condensation
• Evaporation
• Sublimation
• Change in Size or Shape
• NO change occurs in the IDENTITY of the
  substance(s)
• Examples Ice, rain, and STEAM are all WATER

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Chemical Changes

• Atoms in the REACTANTS are REARRAGED to form one
  or more DIFFERENT substances
• OLD chemical BONDS are BROKEN and NEW chemical
  BONDS are FORMED
• Changes DO occur in the identity of the
  compounds since NEW compounds are formed
• Examples
• Fe and O2 form RUST (Fe2O3)
• Ag and S form TARNISH (Ag2S)

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Signs of Chemical Changes

• New substance produced
• Production of a gas
• Change in color
• Change in smell
• Change in heat or light

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Learning Check 1

• Classify each of the following as a
• PHYSICAL CHANGE (P) or a
• CHEMICAL CHANGE (C)
• A. ____ a burning candle
• B. ____ steam coming up from boiling H2O
• C. ____ toasting a marshmallow
• D. ____ cutting a pizza
• E. ____ polishing silver

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Solution 1

• Classify each of the following as a
• PHYSICAL CHANGE (P) or a
• CHEMICAL CHANGE (C)
• A. _C_ a burning candle
• B. _P_ steam coming up from boiling H2O
• C. _C _ toasting a marshmallow
• D. _ P cutting a pizza
• E. _ C _ polishing silver

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Chemical Reaction

• A process in which AT LEAST ONE NEW SUBSTANCE IS
  PRODUCED AS A RESULT OF A CHEMICAL CHANGE.

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A Chemical Reaction

• REACTANTS PRODUCTS
• Draw the contents of these two boxes on your paper

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Learning Check 2

• A. Use the box drawing to determine, how does
  the equation indicate a change in the identity of
  the reacting substances?
• B. Does the equation follow the Law of
  Conservation of Matter? How can you tell?

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Solution 2

1. Use the box drawing to determine, how does an
   equation indicate a change in the identity of the
   reacting substances? The formulas of the
   reactants are different than the formulas of the
   products.
2. Does the equation follow the Law of Conservation
   of Matter? How can you tell? Yes, there are the
   same number and kinds of symbols (atoms) on both
   sides of the chemical equation.

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Writing a Chemical Equation

• Chemical equations give a BEFORE AFTER
  picture of a chemical reaction
• Reactants Products
• MgO C CO Mg
• magnesium oxide TO FORM carbon monoxide
• REACTS with carbon and
  magnesium

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Learning Check 3

• 12 oz of dough, 4 oz mushrooms, 12 slices
  pepperoni, 8 oz cheese and 5 oz tomato sauce are
  used to make a pizza.
• How would you write the recipe above
  as an equation?

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Solution 3

• 12 oz of dough, 4 oz mushrooms, 12 slices
  pepperoni, 8 oz cheese and 5 oz tomato sauce are
  used to make a pizza.
• How would you write the recipe as an equation?
• 12 oz dough 4 oz mshrm
• 12 pep 8 oz chse 1 pizza
• 5 oz tom sauce

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Reading A Chemical Equation

• 4NH3 5O2 ? 4NO 6H2O
• ________ molecules of NH3 REACT with ________
  molecules O2 TO PRODUCE ________ molecules of NO
  and ________ molecules of H2O

FOUR
FIVE
FOUR
SIX
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A Balanced Chemical Equation

• SAME numbers of EACH TYPE OF ATOM on each
  side of the equation
• Al S ? Al2S3
• 2Al 3S ? Al2S3
• When balancing an equation, _______change
  subscripts _________ change ______________

Not Balanced
Balanced
NEVER
COEFFICIENTS
ALWAYS
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Matter is Not Created nor Destroyed

• H2 Cl2 ? 2HCl
• Total Atoms Total Atoms
• H 2, Cl 2 H 2, Cl 2
• Total Mass Total Mass
• 2 (1.0) 2 (35.5) 2 (1.0 35.5)
• 73.0 amu 73.0 amu

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Law of Conservation of Mass

• In any ordinary chemical reaction, MATTER IS NOT
  CREATED or DESTROYED

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Balance Equations with Coefficients

• Add Coefficients IN FRONT of compounds to
  BALANCE the equation
• 4NH3 5O2 4NO 6H2O
• N N
• H H
• O O

4
4
12
12
10
10
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Steps in Balancing An Equation

• Fe3O4 H2 Fe H2O
• Fe Fe3O4 H2 3Fe H2O
• O Fe3O4 H2 3Fe 4H2O
• H Fe3O4 4H2 3Fe 4H2O

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Learning Check 4

• Fe3O4 4H2 3Fe 4H2O
• A. Number of H atoms in the reactants?
• B. Number of O atoms in the reactants?
• C. Number of Fe atoms in the reactants?

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Solution 4

• Fe3O4 4H2 3Fe 4H2O
• A. Number of H atoms in the reactants? 8
• B. Number of O atoms in the reactants? 4
• C. Number of Fe atoms in the reactants? 3

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Learning Check 5

• 6CO2 6H2O sunlight C6H12O6
  6O2
• A. Number of carbon atoms in the reactants?
• B. Number of oxygen atoms in the reactants?
• C. Number of hydrogen atoms in the reactants?
• D. Is this a endo or exothermic reaction? What
  important biological process does this chemical
  equation represent?

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Solution 5

• 6CO2 6H2O sunlight C6H12O6 6O2
• A. of carbon atoms in the reactants? 6
• B. of oxygen atoms in the reactants? 18
• C. of hydrogen atoms in the reactants? 12
• D. Is this a endo or exothermic reaction? What
  important biological process does this chemical
  equation represent? Endothermic Reaction
  Photosynthesis

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Learning Check 6

• Balance each equation. SHOW YOUR WORK!
• A. Mg N2 Mg3N2
• B. Al Cl2 AlCl3
• C. Fe2O3 C Fe
  CO2
• D. Al FeO Fe Al2O3

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Solution 6

• Balance each equation. SHOW YOUR WORK!
• A. Mg N2 Mg3N2
• B. Al Cl2 AlCl3
• C. Fe2O3 C Fe
  CO2
• D. Al FeO Fe Al2O3

3
2
2
3
4
2
3
3
3
2
3
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Types of Chemical Equations

• Synthesis
• Getting Together
• A B ? AB
• ___Fe ___O2 ? ___Fe2O3
• Iron reacts with Oxygen to produce rust

2
3
4
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Types of Chemical Equations

• Decomposition
• Breaking Apart
• AB ? A B
• ___H2O2 ? ___H2O O2 energy
• Hydrogen Peroxide reacts with Oxygen to produce
  water oxygen energy

2
2
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Types of Chemical Equations

• Single Replacement Reaction
• One Exchange
• AB C ? A BC or A BC ? AB C
• Ag H2S ? AgS H2
• Silver Tarnishing

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Types of Chemical Equations

• Double Replacement Reaction
• Two Exchanges
• AB CD ? AC BD
• HCl NaOH ? NaCl H2O
• Acid Base ? Salt Water
• CH3COOH NaHCO3 ? CH3COON2 H2O CO2
• Vinegar Baking Soda ? Sodium Acetate Salt
  Water Carbon Dioxide

(Neutralization)
(Neutralization)
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Learning Check 7

• Determine which type of chemical reaction is
  shown
• CuCl2 H2 S ? CuS 2HCl
• 2H2O ? 2H2 O2
• MgO Fe ? FeO3 Mg
• P4 5O2 ? P4O10

DR
D
SR
S
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• Ag H2S ? AgS H2
• Fe3O4 4H2 ? 3Fe 4H2O
• 3Mg N2 ? Mg3N2
• 3Al 3Cl2 ? 2AlCl3
• HCl NaOH ? NaCl H2O
• 2Fe2O3 3C ? 4Fe 3CO2
• 2Al 3FeO ? 3Fe Al2O3
• 2Fe2O3 ? 4Fe 3O2

SR
SR
S
S
DR
SR
SR
D
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Chemical Reaction Rates

• Reaction Rates refers to HOW FAST A REACTION
  OCCURS

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Chemical Reaction Rates

• Factors that Influence Reaction Rates
• Temperature
• Examples
• Glow sticks in HOT water glow brighter than one
  in cold water
• Antacid dissolves faster in HOT water than cold
  water

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Chemical Reaction Rates

• Factors that Influence Reaction Rates
• Surface Area
• Refers to how much of the outside of a substance
  is exposed
• The greater surface area, the faster the reaction
• Examples
• Lycopodium Powder
• Headache medicine reacts faster in powder form
  than solid form (ex. Goodie Powder versus Tylenol
  Pill)

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Chemical Reaction Rates

• Factors that Influence Reaction Rates
• Concentration
• Refers to how much of a substance there is
• The greater concentration of a reactant, the
  faster the reaction
• Example
• Vinegar Baking Soda in Beaker more vinegar
  produces a faster reaction

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Chemical Reaction Rates

• Factors that Influence Reaction Rates
• Presence of a Catalyst
• Refers to a substance that speeds up a reaction
  but is NOT used up by the reaction
• The catalyst can be recovered unchanged, and
  re-used indefinitely
• Examples
• Yeast in our chemiluminescent elephants
  toothpaste reaction
• Enzymes found in animals that speed up digestion

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Chemical Reaction Rates

• Factors that Influence Reaction Rates
• Presence of an Inhibitor
• Refers to something that slows down or stops a
  chemical reaction
• Examples
• Why do we cover our left over foods?
• Why do we even put food in the fridge?
• Why do we use food preservatives like salts?

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Learning Check 8

• List 4 ways to make a reaction occur faster
  (increase the speed)
• 1.
• 2.
• 3.
• 4.

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Learning Check 9

• List 4 ways to make a reaction occur slower
  (decrease the speed)
• 1.
• 2.
• 3.
• 4.

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Learning Check 10

• See Study Guide From Chapter 7 Test