1 FLASHBACK! Chemical Reactions Types of Chemical Equations Balancing Chemical Equations Reaction...

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FLASHBACK!

Chemical ReactionsTypes of Chemical Equations

Balancing Chemical EquationsReaction Rates

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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Compounds are groups of elements chemically bonded together

2 types we’ve studied: IONIC – bonding where electrons are gained or lost

COVALENT – bonding where electrons are shared

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

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

Changes in PHYSICAL properties1. Melting2. Boiling3. Condensation4. Evaporation5. Sublimation6. Change in Size or Shape

NO change occurs in the IDENTITY of the substance(s)

Examples: Ice, rain, and STEAM are all WATER

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)

1. New substance produced

2. Production of a gas

3. Change in color

4. Change in smell

5. Change in heat or light

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

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

A process in which AT LEAST

ONE NEW SUBSTANCE IS

PRODUCED AS A RESULT OF A

CHEMICAL CHANGE.

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REACTANTS PRODUCTS

Draw the contents of these two boxes on your paper

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?

A. 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.

B. 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.

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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12 oz of dough, 4 oz mushrooms, 12 slices pepperoni, 8 oz cheese and 5 oz

tomato sauce are used to make a pizza.

A.How would you write the recipe above as an equation?

12 oz of dough, 4 oz mushrooms, 12 slices pepperoni, 8 oz cheese and 5 oz tomato

sauce are used to make a pizza.

A.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

4NH3 + 5O2 → 4NO + 6H2O ________ molecules of NH3 REACT with

________ molecules O2 TO PRODUCE

________ molecules of NO and ________

molecules of H2O

FOURFIVE

FOUR SIX

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

NEVERCOEFFICIENTS

ALWAYS

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

→+ +

In any ordinary chemical

reaction, MATTER IS

NOT CREATED or

DESTROYED

Add Coefficients IN FRONT of compounds to BALANCE the equation

4NH3 + 5O2 4NO + 6H2O

N = & N = H = & H = O = & O =

41210

41210

Fe3O4 + H2 Fe + H2O

Fe: Fe3O4 + H2 3Fe + H2O

O: Fe3O4 + H2 3Fe + 4H2O

H: Fe3O4 + 4H2 3Fe + 4H2O

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?

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

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?

6CO2 + 6H2O + sunlight C6H12O6 + 6O2

A. # of carbon atoms in the reactants? 6

B. # of oxygen atoms in the reactants? 18C. # of hydrogen atoms in the reactants? 12D. Is this a endo or exothermic reaction? What important

biological process does this chemical equation represent? Endothermic Reaction; Photosynthesis

Balance each equation. SHOW YOUR WORK!

A. Mg + N2 Mg3N2

B. Al + Cl2 AlCl3

C. Fe2O3 + C Fe + CO2

D. Al + FeO Fe + Al2O3

Balance each equation. SHOW YOUR WORK!

A. Mg + N2 Mg3N2

B. Al + Cl2 AlCl3

C. Fe2O3 + C Fe + CO2

D. Al + FeO Fe + Al2O3

22 3

32 3

42 3 3

3

1. Synthesis

Getting Together

A + B → AB

___Fe + ___O2 → ___Fe2O3

Iron reacts with Oxygen to produce rust

234

2. Decomposition Breaking Apart AB → A + B

___H2O2 → ___H2O + O2 + energy

Hydrogen Peroxide reacts with Oxygen to produce water & oxygen & energy

22

3. Single Replacement Reaction

One Exchange

AB + C → A + BC or A + BC → AB + C

Ag + H2S → AgS + H2

Silver Tarnishing

4. Double Replacement Reaction Two Exchanges

AB + CD → AC + BD

HCl + NaOH → NaCl + H2OAcid + Base → Salt + Water

CH3COOH + NaHCO3 → CH3COON2 + H2O + CO2

Vinegar + Baking Soda → Sodium Acetate Salt + Water + Carbon Dioxide

(Neutralization)

(Neutralization)

Determine which type of chemical reaction is shown:

A.CuCl2 + H2 S → CuS + 2HCl

B.2H2O → 2H2 + O2

C.MgO + Fe → FeO3 + Mg

D.P4 + 5O2 → P4O10

DR

DSR

S

E. Ag + H2S → AgS + H2

F. Fe3O4 + 4H2 → 3Fe + 4H2O

G. 3Mg + N2 → Mg3N2

H. 3Al + 3Cl2 → 2AlCl3

I. HCl + NaOH → NaCl + H2O

J. 2Fe2O3 + 3C → 4Fe + 3CO2

K. 2Al + 3FeO → 3Fe + Al2O3

L. 2Fe2O3 → 4Fe + 3O2

SRSR

SS

DRSR

SRD

• “Reaction Rates” refers to HOW FAST A REACTION OCCURS

• Factors that Influence Reaction Rates

1. Temperature Examples: o Glow sticks in HOT water glow brighter than

one in cold water o Antacid dissolves faster in HOT water than

cold water

• Factors that Influence Reaction Rates2. Surface Area

Refers to how much of the outside of a substance is exposed

The greater surface area, the faster the reaction Examples: o Lycopodium Powdero Headache medicine reacts faster in powder form

than solid form (ex. Goodie Powder versus Tylenol Pill)

• Factors that Influence Reaction Rates3. Concentration

Refers to how much of a substance there is The greater concentration of a reactant,

the faster the reaction Example: o Vinegar & Baking Soda in Beaker – more

vinegar produces a faster reaction

• Factors that Influence Reaction Rates4. 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: o Yeast in our “chemiluminescent elephant’s

toothpaste” reactiono Enzymes found in animals that speed up digestion

• Factors that Influence Reaction Rates5. Presence of an Inhibitor

Refers to something that slows down or stops a chemical reaction

Examples: o Why do we cover our left over foods?o Why do we even put food in the fridge?o Why do we use food preservatives like salts?

List 4 ways to make a reaction occur faster

(increase the speed): 1.

2.3.4.

List 4 ways to make a reaction occur slower (decrease the speed):

1. 2.3.4.

See Study Guide From Chapter 7

Test