Download CHEMICAL REACTIONS

CHEMICAL REACTIONS
L.H.S.
R.H.S.
Reactants
Products
FROM LAW OF CONSERVATION OF MASS:
Must have Same Number of Atoms of
Each Type on Both Sides of the Equation
SIMPLE COMBUSTION
REACTION
Example:BURN PROPANE IN AIR (Gas Grill)
Propane +Oxygen Carbon Dioxide+ Water
C 5 H 12 (g) + O 2 (g)
 CO 2 (g)+
H 2O (l)
PHASES OF REACTANTS &
PRODUCTS
NOTE: Indicate physical state of
each species by (phase)
e.g. (g) = gas
(s) = solid
(l) = liquid
(aq.) = aqueous solution
BALANCING CHEMICAL
EQUATIONS
Simple Approach
1. ASSIGN COEFFICIENT OF 1 TO MOST
COMPLEX COMPOUND
2. LOOK FOR ELEMENTS THAT APPEAR
ONLY ONCE IN EQN., AND TRY
COEFFICENTS
C5 H12 (g) + O 2 (g) CO 2 (g) + H 2O (l)
BALANCE C
(c) Balance C
C5 H12 (g) + O2 (g)
 5 CO2 (g)+ H2O(l)
BALANCE H
(b) Balance H
C5H12 (g) +O2 (g)  CO 2 (g) + 6 H2O (l)
BALANCE O
(c) Balance O
(i) ADD UP O ON RHS = 5 x 2 + 6 x 1 = 16
(ii) O APPEARS AS O2 ON LHS  NEED
16/2 x O2
1C5H12 (g) + 16/2 O2 (g) 5 CO2 (g) + 6 H2O(l)
FINAL POLISHING
CONVERT TO WHOLE NUMBERS:
1C5H12 (g)+8O 2 (g)5CO2 (g)+6H2O(l)
CHECK COEFFICIENTS
LHS
RHS
(1 x 5 C) = 5 C
5C
(1 x 12 H) = 12 H
(6 x 2 H) = 12 H
(8 x 2 O) = 16 O (5 x 2 O + 6 x 1 O)= 16 O
BUT… WHAT DOES THIS
EQUATION MEAN?
1 C5 H12 (g) + 8 O2 (g)  5 CO2 (g)+ 6 H 2O(l)
• 1. = 1 MOLE of Propane Reacts with 8
MOLES of Oxygen to produce 5 MOLES of
Carbon Dioxide + 6 MOLES of Water
• OR
• 2. = 1 MOLECULE of Propane Reacts with
8 MOLECULES of Oxygen to produce
5 MOLECULES of Carbon Dioxide +
6 MOLECULES of Water