Transcript Lec Balancing Chemical Equations.2014 Tiered

2 Minute Drill
Homework
Complete the Chemical Equation worksheet
Learner Objective
Learner will be able to balance the reactants and products of a
chemical reaction equation
.
Lec: Balancing Chemical
Equations
NaOH + HCl
NaCl + H2O
When balancing a chemical equation the quantity
and types of elements in the reactants has to be equal
to the quantity and types of elements in the products.
NaOH + HCl
NaCl + H2O
Step 1. Break the reactants and products down into the type
of elements.
Na
O
H
Cl
Na
O
H
Cl
NaOH + HCl
NaCl + H2O
Step 2. Place the quantity of each element in the reactants
and products.
Na:1
O:1
H:2
Cl:1
Na:1
O:1
H:2
Cl:1
NaOH + HCl
NaCl + H2O
Step 3. Determine if the quantities of each element are the
same. If they are you will state “The chemical equation is
balanced. If not, state which elements are not.
Na:1
Na:1
O:1
O:1
H:2
H:2
Cl:1
Cl:1
Fe(s) + O2
Step 1:
Fe
O
Fe2O3
Fe
O
Fe(s) + O2
Fe: 1
O: 2
Fe2O3
Fe: 2
O: 3
Is this chemical equation balanced?
The chemical equation is not balanced because both Fe and O
are not equal.
HCl + O2
Cl2 +
H2O
Is this chemical equation balanced?
Balancing a chemical equation
with a Chemical Group
Pb(NO3)2 + KI
PbI2+ KNO3
Balancing a chemical equation
with a Chemical Group
Pb(NO3)2 + KI
PbI2+ KNO3
NO3 is a chemical group on both sides
of the chemical equations.
Balancing an chemical equation with a Chemical Group
Pb(NO3)2 +
Step 1
Pb:
NO3:
K:
I:
KI
PbI2+
Pb:
NO3 :
K:
I:
KNO3
Balancing an chemical equation with a Chemical Group
Pb(NO3)2 +
KI
Pb: 1
NO3: 2
K: 1
I: 1
Is this chemical equation balanced?
PbI2+
Pb :1
NO3 :1
K :1
I: 2
KNO3
Challenger
Balancing a Chemical Equation
when the number of elements on
both sides are not equal.
Fe(s) + O2
Fe: 1
O: 2
Fe2O3
Fe: 2
O: 3
Fe(s) + 3O2
2Fe2O3
Step 3:
(reactants)
(products)
Fe: 1
Fe: 2
O: 2 x 3 = 6 O: 3 x 2 = 6
Fe(s) +
3O2
2Fe2O3
Step 3:The increase in O on the product side causes the Fe to
increase too and now needs to be increased.
Fe: 1
O: 2 x 3 = 6
Fe 2 x 2 = 4
O: 3 x 2 = 6
4 Fe(s) + 3 O2
Fe 1 x 4 = 4
O 2x3=6
2 Fe2O3
Fe 2 x 2 = 4
O 3x2=6
4 Fe(s) +
3 O2
2 Fe2O3
What does this chemical reaction make?
4 Fe(s) +
3 O2
2 Fe2O3
What does this chemical reaction make?
Answer: Rust!
Balancing an chemical equation with a Chemical Group
Pb(NO3)2 +
Pb: 1
NO3: 2
K: 1
I: 1
KI
PbI2+
Pb :1
NO3 :1
K :1
I: 2
KNO3
Pb(NO3)2 + KI
Pb: 1
NO3: 2
K: 1
I: 1
PbI2+
2KNO3
Pb :1
NO3 :1 x 2 =2
K :1
I: 2
Pb(NO3)2 + 2KI
Pb: 1
NO3: 2
K: 1 x 2 = 2
I: 1
PbI2+
2KNO3
Pb :1
NO3 :1 x 2 = 2
K :1 x 2= 2
I: 2
Pb(NO3)2 + 2KI
Pb: 1
NO3: 2
K: 1 x 2 = 2
I: 1 x 2 = 2
PbI2+
2KNO3
Pb :1
NO3 :1 x 2 =2
K :1 x 2= 2
I: 2
H2SO4 + NaOH
HOH + Na2SO4