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Chemical Reactions

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What is a Chemical Equation and Why do we use them? ... Balancing. Chemical Equations. Reactant(s) Product(s) MgCO3 (s) MgO (s) CO2(g) ... – PowerPoint PPT presentation

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Title: Chemical Reactions


1
Chemical ReactionsChemical Equations
2
Chemical Reactions
Chemical Change
  • A process involving a substance or substances
    changing into a new substance or substances

3
Chemical Reactions
Evidence of a chemical reaction
4
Chemical Reactions
Evidence of a chemical reaction
1) A permanent color change
2) A gas is produced
3) Energy is exchanged
4) A precipitate is produced
5
Chemical Equations
  • A statement using chemical formulas to describe
    the identities and relative amounts of reactants
    and products involved in the chemical reaction

6
  • Reactant(s) ? Product(s)

7
  • MgCO3 ? MgO CO2

8
  • MgCO3 ? CO2 MgO

9
  • MgCO3 (s) ? MgO (s) CO2(g)

Phases of Components (s) solid (l)
liquid (g) gas (aq) aqueous
10
Physical Change Vs. Chemical Change
11
Physical Change
Chemical Change
12
Physical Change
Chemical Change
Phase Changes Dissolving Mixing Breaking Separatin
g Filtering
Rearrange Atoms New Substances form
13
Did a chemical change occur?
  1. Permanent Color Change Occurs
  2. Precipitate Formed
  3. Gas is Released
  4. Energy is Exchanged Temperature

14
Chemical Reaction Demonstration
  • Permanent Color Change
  • CuSO4 (Aq) Zn (s) ? ZnSO4 (Aq) Cu (s)
  • Blue Gray Clear Black
  • The Zn and Cu are Switching, this is known as a
    single replacement Reaction.
  • Gas is Produced
  • HCl (l) Zn (s) ? ZnCl (Aq) H2 (g)
  • Energy is Exchanged
  • Mg (s) O2 (g) ? MgO (s)
  • Rapid Oxidation
  • Precipitate is Formed
  • Pb(NO3)2 (Aq) K2CrO4 (Aq) ? KNO3 (Aq)
    PbCrO4 (s)
  • Clear Bright Yellow

15
Practice Exercise 1
  • Define Chemical Reaction
  • How do we know a chemical reaction has taken
    place?
  • What is a Chemical Equation and Why do we use
    them?
  • What are the initial constituents of a chemical
    reaction? What are the end products called?
  • What do the following symbols stand for?
  • s l g aq

16
Types of Chemical Equations
17
Synthesis
  • Putting things together
  • Also known as Direct Combination.

2 Na Cl2 2 NaCl 4 Al 3 O2 2 Al2O3
18
Decomposition
  • Breaking things down/Taking apart
  • AKA Analysis

2 KClO3 2 KCl 3 O2 3 MnO2 Mn3O4 O2
19
Single Replacement
  • Replacing one element in a compound with another
    element.

2 Al 6 HCl 2 AlCl3 3 H2 2 NaBr Cl2
2 NaCl Br2
20
Double Replacement
  • Switching one element from a compound with
    another element from a different compound.

2 AgNO3 MgCl2 2 AgCl Mg(NO3)2 HCl
NaOH NaCl H2O
21
Others
  • Combustion
  • Rapid Oxidation
  • XXXX O2 CO2 H2O
  • Oxidation
  • Add Oxygen (Combustion)
  • Reduction
  • Acid Base Neutralization
  • Etc

22
(No Transcript)
23
HW
  • Due Monday
  • Read outline page 249-255

24
Exothermic Reactions
  • Release or give off heat.
  • Heat is a byproduct of the reaction.
  • Temperature increases as the bonds between
    products are formed.
  • Examples
  • Combustion, Respiration, Oxidation

25
Endothermic Reactions
  • Take in or absorb Heat from the surroundings.
  • Temperature decreases as the reaction progresses.
  • Heat is used to break bonds of reactants.
  • Decomposition or Analysis Reactions

26
Oxidation
  • Removing Electrons

27
Reduction
  • Adding Electrons

28
Rate of Reaction
  • Reactions occur at different speeds.
  • The time it takes for reactants to become
    products.

29
Catalysts
  • They speed up reactions without being affected
    themselves.
  • They stay the same
  • Enzymes in living organisms.
  • Lowers activation energy
  • The amount of energy needed to start a reaction.

30
Speeding Up Reactions
  • Temperature, Energy, Pressure, Surface Area,
    Concentration, Collisions, Catalyst.

31
Measuring Rates of Reactions
  • Measure Reactants
  • Measure Products

32
BalancingChemical Equations
33
Reactant(s)
Product(s)
34
  • MgCO3 (s) ? MgO (s) CO2(g)

Phases of Components (s) (l) (g)
(aq)
35
  • 1 MgCO3 (s) ? 1 MgO (s) 1 CO2(g)

36
  • 1 MgCO3 (s) ? 1 MgO (s) 1 CO2(g)

Reactants
Products
37
5 atoms
5 atoms
  • 1 MgCO3 (s) ? 1 MgO (s) 1 CO2(g)

38
  • H2 O2 ? H2O

39
  • 2 H2 1 O2 ? 2 H2O

H2 H2 O2 ? H2O H2O
40
  • 2 H2 1 O2 ? 2 H2O

H2 H2 O2 ? H2O H2O
41
  • Ca Cl2 ? CaCl2

42
  • Na Cl2 ? NaCl

43
  • Fe2O3 ? Fe O2

44
  • AgNO3 NaCl ? NaNO3 AgCl

45
  • FeS2 O2 ? Fe2O3 SO2

46
  • 4 FeS2 11 O2 ? 2 Fe2O3 8 SO2

47
  • NH4OH Ni(NO3)2 ? NH4NO3 Ni(OH)2
  •  

48
  • NH4OH Ni(NO3)2 ? NH4NO3 Ni(OH)2
  •  

49
  • Na2CO3 Fe(NO3)3 ? Fe2(CO3)3 NaNO3

50
Na2CO3 Fe(NO3)3 ? Fe2(CO3)3 NaNO3
  • 3 Na2CO3 2 Fe(NO3)3 ? Fe2(CO3)3 6 NaNO3
  • Balanced!!!

51
  • H3PO4 Ca(OH)2 ? Ca3(PO4)2 H2O

52
  •  NH4OH H3PO4 ? (NH4)3PO4 H2O
  •  

53
  • Al(OH)3 H2SO4 ? Al2(SO4)3 H2O
  •  

54
  • C6H6 O2 ? CO2 H2O
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