1. Mr. Kinton Honors Chemistry
Chemical Reactions
Mr. Kinton
Honors Chemistry

2. Properties of Matter Every substance has a unique set of properties
Physical or Chemical
Intensive (do not depend on amount) or Extensive (depend on amount)
Properties of Matter

3. Physical Properties/Changes
Measured without changing composition or identity
Color
Melting Point
Change that occurs in physical appearance
Phase Change
Size
Shape
Physical Properties/Changes

4. Chemical Properties/Changes
Way a substance may change or react
Flammability
Oxidation State
Transformation to a completely different substance
Burning
Gas produced
Chemical Properties/Changes

5. Indicators of a Chemical Change
Change in color
Leaves that change during Autumn
Formation of a precipitate
Typically occurs when 2 aqueous solutions mix
Indicators of a Chemical Change

6. Indicators of a Chemical Change
Formation of a gas
Occurs when alkali metals react with HCl
Energy is released
Heat
Light
Indicators of a Chemical Change

7. There are ways to test for the presence of specific gases
O2- Burning splint will glow brighter
H2- Burning splint will produce a “pop” sound
CO2- Burning splint will go out, lime water
Common Tests for Gases

8. Law of Conservation of Mass
Discovered by Antoine Lavoisier
Total mass of all substances before and after a reaction must be the same
Confirmed Dalton’s point that atoms could not be created or destroyed
Law of Conservation of Mass

9. Law of Conservation of Mass

10. In addition to mass being conserved, charge and energy will also be conserved
If heat is produced the same amount is somewhere else
If an ion is formed then something else will gain the charge
Chemical Reactions

11. Chemical Equations Chemical reactions written in a concise way
There are 2 sides to every equation:
Reactants: starting substance, found on the left
Products: Ending substance, found on the right
Chemical Equations

12. Information in Chemical Equations
(g) – gas
(l) – liquid
(s) – solid
(aq) – aqueous; dissolved in water
∆ – heat
hν – electromagnetic radiation
Any other conditions for the reaction are shown above or below the yield sign.
Information in Chemical Equations

13. How to write a Chemical Equation
When hydrogen burns, it reacts with oxygen in the air to form water.
2H2 + O H2O
2- Coefficient
+ - Reacts with
2- Subscript
Yields
How to write a Chemical Equation

14. Methane reacts with oxygen to form carbon dioxide gas and water vapor
Sodium metal reacts with liquid water to yield aqueous sodium hydroxide and hydrogen gas
Iron metal reacts with oxygen gas to form solid iron (III) oxide
You Try!

15. All equations we work with must be balanced to obey the Law of Conservation of Mass
When balancing we always use coefficients
NEVER change the subscripts
Balancing Equations

16. Unbalanced Equation
Balanced Equation
Balancing Equations

17. How to Balance an Equation
It is mainly trial and error
Best to balance elements that occur the fewest
Always save oxygen for last
Use coefficients to balance each atom
How to Balance an Equation

18. How to Balance an Equation
Al(s) + HCl(aq) AlCl3(aq) + H2(g)
How to Balance an Equation

19. How to Balance an Equation
C2H4(g) + O2(g) CO2(g) + H2O(g)
How to Balance an Equation

20. You Try! SO2(g) + O2(g) SO3(g) P2O5(s) + H2O(l) H3PO4(aq)
Mg3N2(s) + H2SO4(aq) MgSO4(aq) + (NH4)2SO4(aq)
You Try!

21. Types of Chemical Reactions
Synthesis/Combination
Decomposition
Combustion
Single Replacement/Displacement
Double Replacement/Displacement
Types of Chemical Reactions

22. Synthesis/Combination
Let us examine a real world application:
Synthesis/Combination

23. Synthesis/Combination
When two or more substances react to form one product
2Mg(s) + O2(g) MgO(s)
General form of A + B  AB
Synthesis/Combination

24. Decomposition

25. Decomposition Reactions
When one substance breaks down to produce two or more substances
CaCO3(s)  CaO(s) + CO2(g)
General form of AB  A + B
Decomposition Reactions

26. Combustion Reaction Rapid reaction that produces a flame
C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g)
Hydrocarbon and Oxygen will react to produce carbon dioxide and water always!
Combustion Reaction

27. Single Replacement

28. When one substance replaces another in a compound to form a new one
Zn(s) + CuCl2(aq)  Cu(s) + ZnCl2(aq)
General form: A + BC  B + AC
Must obey the activity series
Single Replacement

29. Activity Series

30. Activity Series and Reactions
A reaction will take place if it is higher up on the activity series than the element it is trying to replace
Metals will only replace metals
Nonmetals will only replace nonmetals
If the element cannot replace it then write No Reaction
Activity Series and Reactions

31. Double Displacement

32. When two compounds interact to from an aqueous product and either:
A precipitate
Gas
General form: AB + CD  AD + BC
Double Replacement

33. Use the reference tables to determine the solubility of the products
If 2 aqueous products are produced write No Reaction
Solubility Rules

34. You Try! 2NaCl  2Na + Cl2 2. H2 + Cl2  2HCl
C6H6 + 15O2  12CO2 + 6H2O
KBr + H2SO4  K2SO4 + 2HBr
5. H2SO3 H2O + SO2
6. NaCl + AgNO3  NaNO3 + AgCl
C3H6 + 9O2  6CO2 + 6H2O
8. Mg + HCl  MgCl2 + H2
Na + I2  2NaI
10. 3H2 + N2  2NH3
11. Zn + 2HCl  ZnCl2 + H2
12. 2Na + Br2  2NaBr
You Try!

35. For Synthesis and Decomposition use the reference table to determine what type of each you have
Combustion is always the same CO2 and water
Single Replacement use the activity series
Double Replacement use the solubility rules
Predicting Products

36. Oxidation and Reduction Reactions

37. Oxidation-Reduction reactions or Redox reactions occur when electrons are transferred between reactants
Responsible for many different processes
Rusting of iron
Construction of batteries
Electroplating
Manufacture and action of bleach
What are they?

38. Oxidation Number- the hypothetical charge assigned to an atom based on a set of rules
Oxidation- when a substance loses electrons
Reduction- when a substance gains electrons
Oxidizing agent/oxidant- the substance that makes it possible for another substance to be oxidized
Reducing agent/reductant- the substance that makes it possible for another substance to be reduced
Vocabulary

39. Assigning Oxidation Numbers
1. For an atom in it’s elemental form the oxidation number is always 0
Ex) H2 has an oxidation number of 0
2. For any monatomic ion the oxidation number is equal to the charge.
K+ has an oxidation number of +1
S2- has an oxidation number of -2
Assigning Oxidation Numbers

40. Assigning Oxidation Numbers
3. Nonmetals usually have negative oxidation numbers but they can have positive ones also
A) The oxidation number of oxygen is usually -2. The only exception is found in peroxide (O22-) which is -1
B) Hydrogen has an oxidation number of +1 when bonded to nonmetals and -1 when bonded to metals
C) The oxidation number of fluorine is -1 in all compounds. The other halogens have an oxidation number of -1 unless they are in an oxyanion.
Assigning Oxidation Numbers

41. Assigning Oxidation Numbers
4. The sum of the oxidation numbers in a neutral compound must be 0. For polyatomic ions the sum of oxidation numbers must equal the charge.
Assigning Oxidation Numbers

42. Identifying a the parts of a Redox Reaction
Let’s examine the reaction of magnesium metal in hydrochloric acid:
Mg(s) + 2HCl(aq)  MgCl2(aq) + H2(g)
We want to be able to determine which substance was oxidized? Reduced?
Which substance is the oxidizing agent? Reducing agent
Identifying a the parts of a Redox Reaction

43. Identifying the parts of a Redox Reaction
Here is another example that takes place within a nickel-cadmium rechargeable battery
Cd(s) + NiO2(s) + 2H2O(l)  Cd(OH)2(s) + Ni(OH)2(s)
Identifying the parts of a Redox Reaction

44. Half-Reactions Equations that show only oxidation or only reduction
Allows us to track where the electrons have traveled during the redox reaction
Sn2+(aq)  Sn4+(aq) + 2e- (oxidation reaction)
2Fe3+(aq) + 2e-  2 Fe2+(aq) (reduction reaction)
Half-Reactions

45. Ionic Equations Complete Net Ionic
Show all of the ions present in a chemical reaction
Anything that is aqueous can be written as an ion
Allows us to see the driving force within a reaction
Shows only the ions responsible for the reaction
Will have 2 ions and either a (s), (l), or (g) product
Spectator Ions: did not participate in the reaction
Ionic Equations

46. Example

47. Write the complete ionic and net ionic equations for each of the following reactions:
3 (NH4)2CO3 (aq) + 2 Al(NO3)3 (aq) --> 6 NH4NO3 (aq) + Al2(CO3)3 (s)
Example

48. Complete Ionic Equation: 6 NH4+ (aq) + 3 CO32- (aq) + 2 Al3+ (aq) + 6 NO3- (aq)  6 NH4+ (aq) + 6 NO3- (aq) + Al2(CO3)3 (s) Net Ionic Equation: 2 Al3+ (aq) + 3 CO32- (aq)  Al2(CO3)3 (s)
Answer