Chemical Reactions and Equations

2.  Is the process by
which a chemical
change takes place.
 A change where a
new substance
is formed.

3.  Is the shorthand way of
expressing chemical reaction
using numbers, symbols
and formula.

4. REACTANTS
The starting materials
These are the
substances that
changes when it is
combined with another
substance in a
chemical reaction
PRODUCTS
The new substance
The substances that
result of the chemical
reaction

6. COEFFICIENT SUBSCRIPT
is a number before
the symbol or formula
of a substance
is the number of
atoms of the element
found in the
substance

7. Symbols Meaning
+ used to separate one reactant or
product from one another.
Can be read as “reacts with”
when used in reactant , read as
“and” when it is used in product.
used to separate the reactants
from the products
read as "yields" or "produces" in
an equation.
(s) indicates that the substance is in
the solid state.

8. Symbols Meaning
(l) indicates that the substance is in
the liquid state.
(g) indicates that the substance is in
the gas state.
(aq) indicates that the substance is
dissolved in water
comes from the term “aqueous”
indicates that there is heat
applied or needed to make the
reaction proceed.

9. Sodium + Water
Sodium Hydroxide + Hydrogen gas
EXAMPLE
:
𝑵𝒂(𝒔) +2 𝑯 𝟐 𝑶(𝒍) NaO𝑯(𝒔) + 𝑯 𝟐(𝒈)
Reactants Symbol Products
Coefficient
Subscript

10. C(s) + O2(g) CO2(g) + energy
Mg(s) + Cl2(g) MgCl2(s)
TRY THIS:

11.  the sum of the masses of the products is
always the same as the sum of the masses of
the reactants.
 states that mass is neither created nor
destroyed in any ordinary chemical reaction.

12. 1. Check for diatomic molecules.
-are molecules composed of only
two atoms, of either the same or different
chemical elements.
This includes 𝐻2, 𝑂2, 𝑁2, 𝐶𝑙2,
𝐵𝑟2, 𝐹2 and 𝐼2.

14. 2. Check whether the chemical formulas of all
the reactants and products are correct. Check
the total number of atoms of each element on
each side of the equation.
3. A polyatomic ion appearing unchanged on
both sides of the equation is counted as a single
unit.

15. 4. Balance the elements one at a time by using
coefficients. Must not attempt to the balance the
equation by changing the subscripts in the
chemical formula of a substance.

16. 5. Check each atom or polyatomic ion to be
sure that the equation is balanced.

17. EXAMPLES
:

18. STEP 1:
Element Reactants Products
H 2 2 Equal
O 2 1 Not
equal

19. STEP 2:

20. Element Reactants Products
N 2 1 Not
equal
H 2 3 Not
equal

25. Chemical Equation during Photosynthesis:
CO2(g) + H2 𝑶(𝒍) → C6H12O6(s) + O2(g)

26. Chemical Equation when cooking in the
gas stove:
CH4(g) + O2(g) → CO2(g) + H2 𝑶(𝒍)

27. Chemical Equation in the Formation of Rust:
Fe(s) + O2(g) → Fe2O3(s)

28. 1. 6 CO2(g) +6 H2 𝑶(𝒍) → C6H12O6(s) + 6 O2(g)
2. CH4(g) + 3 O2(g) → CO2(g) +2 H2 𝑶(𝒍)
3. 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)

29. DIRECTIONS: On a one whole sheet of
paper, Answer the following questions.
1. What are the types of chemical
reactions?
2. Give at least 3 examples on each type.

30.  Davis, Raymond E. et.al.(2010). Modern
Chemistry. (USA: Holl, Rinehart, Winston).
 de Borja, Rebecca S.(2011).Chemistry.
(Philippines: Books Atbp. Publishing Corp.)
 Hill, John W. (2010). Chemistry for Changing
Times. (Singapore: Prentice Hall Companies).