Chemical reactions involve the transformation of reactants into products, changing their physical and chemical properties. Key evidence of these reactions includes energy changes, color or odor changes, gas evolution, and precipitation formation. Various types of reactions, such as synthesis, decomposition, displacement, and combustion, are influenced by factors like temperature, particle size, catalysts, and concentration.

1. CHEMICALCHEMICAL
REACTIONSREACTIONS

2. ChemiCal ReaCtionChemiCal ReaCtion

3. Chemical ReactionChemical Reaction
It is a process in which the physical
and chemical properties of the original
substances change as new substances
with different physical and chemical
properties are formed.
Two kinds of substances:
1. The substances present before the
change.
2. The substances formed by the change.

4. Reactants and
Products
• ReactantsReactants
–present at the beginning of the
reaction
• Products
–are the substances formed by the
chemical reaction
Example: burning natural gas
• CH4 + 2O2 > CO2 +2H2O

5. LAW OF CONSERVATIONLAW OF CONSERVATION
OF MASSOF MASS

6. EVIDENCES OFEVIDENCES OF
CHEMICAL REACTIONSCHEMICAL REACTIONS

7. 1. Taking and giving off energy1. Taking and giving off energy
• ENDOTHERMIC
– Reactions where energy is absorbed.
– Ex. Cooking of food and Photosynthesis
• EXOTHERMIC
– Reactions that involve the release of
energy.
– Ex. Explosion of firecrackers and burning
of coal

8. 1. Taking and giving off energy1. Taking and giving off energy

9. 2. Color/odor Change2. Color/odor Change
• Ex. Ripening of fruits
3. Evolution of Gas
• The release of gases
• Ex. When you dissolve a tablet of
alkaseltzer in water, bubbles are
produced.

10. 3. Evolution of Gas

11. 4. Formation of Precipitation4. Formation of Precipitation
• PRECIPITATE is an insoluble solid that
is formed when two liquids react.
• Ex. Combination of vinegar and milk

12. CHEMICALCHEMICAL
EQUATIONSEQUATIONS

13. CHEMICAL EQUATION

14. CHEMICAL EQUATION

15. CHEMICAL FORMULA

16. CHEMICAL FORMULA

17. CHEMICAL FORMULA

18. CHEMICAL FORMULA

19. CHEMICAL FORMULA

20. Balancing
Chemical
Equations

23. BALANCING EQUATION
CH4 + O2 CO2 + H2O

24. BALANCING EQUATION
• CH4 + O2 -> CO2 + H2O
• Balanced? No
• Reactants: C=1, H=4, O=2
• Products: C=1, H=2, O=3
• H and O not equal
• Use coefficients to balance equations
• CH4 + 2O2 -> CO2 + 2H2O
• C=1, H=4, O=4 -> C=1, H= 4, O=4

25. Balancing Chemical
Equations

26. Balancing
Chemical
Equations

28. Balance the following equations:

29. TYPES OF CHEMICAL
REACTIONS

30. A. COMBINATION/ Synthesis
REACTION
• A reaction when 2 or more reactants
combine to form a single product.
• The general formula for this reaction
is : A + B  AB
Example:
N2 +2O2  2 NO2

31. B. DECOMPOSITION
REACTION
• In this reaction, a single reactant
breaks down into simpler ones. (2 or
more products).
• The general formula for this reaction
is: AB  A + B C
Example:
2 H2O  2H2 +O2

32. C. SINGLE DISPLACEMENT or
(Replacement) REACTION
• This is when one element replaces another
element from a compound.
• The more active element takes the place of
the less active element in a compound.
• The general formula for this reaction is:
A + BC  AC + B
Example:

33. D. DOUBLE DISPLACEMENT REACTION
(Metathesis)
• This is when the positive ions (cations) and
negative ions (anions) of different
compounds switch places, forming two
entirely different compounds.
• The general formula for this reaction is:
AB + CD  AD + CB
Example:

35. E. COMBUSTION (Burning)
REACTION
• This is when oxygen combines with a
hydrocarbon to form a water and
carbon dioxide.
• Example of which is the burning of
butane gas.
C4 H 10 + O2  CO2 + H2O

36. F. ACID-BASE REACTION
• This is a special kind of double
displacement reaction that takes
place when an acid and base react
with each other.
• The H+ of the acid reacts with the
OH- of the base forming water. The
other product is salt.
Example of which is:
HCI + NaOH  NaCI + H2O

37. Are a burning vehicle and a
puppy undergoing the same
kind of chemical reaction?
What reaction could this
be?

38. FACTORS AFFECTINGFACTORS AFFECTING
RATES OF CHEMICALRATES OF CHEMICAL
REACTIONSREACTIONS

39. COLLISION THEORY
• explains how collision between
reactant molecules may or may not
result in a successful chemical
reaction.
• Effective collisions between
molecules, which result in the
formation of products, only occur
when the following two conditions
are met:
a. the colliding molecules should possess a
minimum kinetic energy, known as activation

40. Svante Arrhenius (1888)
• suggested that particles must possess a
certain minimum amount of kinetic energy
in order to react. The energy diagram is
shown below.

41. ACTIVATION ENERGY
• It is needed to break the bond between
reactant molecules to form new bonds
leading to formation of the products.
• Minimum kinetic energy required for
reaction.

42. A. TEMPERATURE
• The higher the
temperature, the higher
the rate of reaction.

43. B. PARTICLE SIZE OR
SURFACE AREA
• Smaller particles size have bigger
surface area.
• Bigger surface area means bigger
exposed portions of a solid which
are available points of contact
between reactants.

44. C. CATALYST
• A catalyst provides an energy
pathway needed to start a
reaction, therefore increasing
the reaction rate.
• The presence of catalyst
speeds up the rate of reaction.

45. D. CONCENTRATION
It is a measure of the
number of particles in a given
volume.
The higher the concentration,
the faster the rate of reaction.

46. .

47. GROUP ACTIVITY:
1. Using any form of media, prepare a visual presentation of a
chemical reaction involved in:
•Group 1: a. Food Processing and preservation
b. Fire control
•Group 2: a. Corrosion Control
b. Photochemical Smog
•Group 3: a. Haber process
b. Catalytic Converter
•Group 4: a. Formation of ozone layer in the stratosphere
b. Formation of acid rain
2. Research on how a specific chemical reaction poses useful
or harmful effects to life and the environment
3. Present and discuss to class your visual presentation