Download Steps and Rules for Balancing Equations

Balancing Equations
How Many Atoms are There?
How Many Atoms are There?
Cl2
How Many Atoms are There?
Cl2
How Many Atoms are There?
Cl2
2 Cl
How Many Atoms are There?
Cl2
2 Cl
How Many Atoms are There?
Cl2
2 Cl
2 Cl2
How Many Atoms are There?
Cl2
2 Cl
2 Cl2
How Many Atoms are There?
How Many Atoms are There?
1. H2O
How Many Atoms are There?
1. H2O
Two H, One O
How Many Atoms are There?
1. H2O
2. Fe2O3
Two H, One O
How Many Atoms are There?
1. H2O
2. Fe2O3
Two H, One O
Two Fe, Three O
How Many Atoms are There?
1. H2O
Two H, One O
2. Fe2O3 Two Fe, Three O
3. (NH4)2CO3
How Many Atoms are There?
1. H2O
Two H, One O
2. Fe2O3 Two Fe, Three O
3. (NH4)2CO3 Two N, Eight H, One C, Three O
How Many Atoms are There?
1.
2.
3.
4.
H2O
Two H, One O
Fe2O3 Two Fe, Three O
(NH4)2CO3 Two N, Eight H, One C, Three O
Pt(SO4)2
How Many Atoms are There?
1.
2.
3.
4.
H2O
Two H, One O
Fe2O3 Two Fe, Three O
(NH4)2CO3 Two N, Eight H, One C, Three O
Pt(SO4)2 One Pt, Two S, Eight O
How Many Atoms are There?
1.
2.
3.
4.
5.
H2O
Two H, One O
Fe2O3 Two Fe, Three O
(NH4)2CO3 Two N, Eight H, One C, Three O
Pt(SO4)2 One Pt, Two S, Eight O
Ca(CH3COO)2
How Many Atoms are There?
1.
2.
3.
4.
5.
H2O
Two H, One O
Fe2O3 Two Fe, Three O
(NH4)2CO3 Two N, Eight H, One C, Three O
Pt(SO4)2 One Pt, Two S, Eight O
Ca(CH3COO)2 One Ca, Four C, Six H, Four O
How Many Atoms are There?
1.
2.
3.
4.
5.
6.
H2O
Two H, One O
Fe2O3 Two Fe, Three O
(NH4)2CO3 Two N, Eight H, One C, Three O
Pt(SO4)2 One Pt, Two S, Eight O
Ca(CH3COO)2 One Ca, Four C, Six H, Four O
3NaNO3
How Many Atoms are There?
1.
2.
3.
4.
5.
6.
H2O
Two H, One O
Fe2O3 Two Fe, Three O
(NH4)2CO3 Two N, Eight H, One C, Three O
Pt(SO4)2 One Pt, Two S, Eight O
Ca(CH3COO)2 One Ca, Four C, Six H, Four O
3NaNO3 Three Na, Three N, Nine O
How Many Atoms are There?
1.
2.
3.
4.
5.
6.
7.
H2O
Two H, One O
Fe2O3 Two Fe, Three O
(NH4)2CO3 Two N, Eight H, One C, Three O
Pt(SO4)2 One Pt, Two S, Eight O
Ca(CH3COO)2 One Ca, Four C, Six H, Four O
3NaNO3 Three Na, Three N, Nine O
2Sn(NO2)4
How Many Atoms are There?
1.
2.
3.
4.
5.
6.
7.
H2O
Two H, One O
Fe2O3 Two Fe, Three O
(NH4)2CO3 Two N, Eight H, One C, Three O
Pt(SO4)2 One Pt, Two S, Eight O
Ca(CH3COO)2 One Ca, Four C, Six H, Four O
3NaNO3 Three Na, Three N, Nine O
2Sn(NO2)4 Two Sn, Eight N, Sixteen O
The Law of Conservation of Mass
The Law of Conservation of Mass
• The law of conservation of mass states
that matter can neither be created or
destroyed
The Law of Conservation of Mass
• The law of conservation of mass states
that matter can neither be created or
destroyed
• This means atoms are neither created or
destroyed, only rearranged in a chemical
reaction
Chemical Equations
Chemical Equations
• Chemical equations are like “recipes” that
describe the ingredients and products of a
chemical reaction.
Chemical Equations
• Chemical equations are like “recipes” that
describe the ingredients and products of a
chemical reaction.
K + O2
K2O
Chemical Equations
• Chemical equations are like “recipes” that
describe the ingredients and products of a
chemical reaction.
K + O2
Reactants
K2O
Chemical Equations
• Chemical equations are like “recipes” that
describe the ingredients and products of a
chemical reaction.
K + O2
K2O
Reactants
Products
Chemical Equations
• Chemical equations are like “recipes” that
describe the ingredients and products of a
chemical reaction.
K + O2
K2O
Reactants
Products
The arrow means “produces”
Chemical Equations
• Chemical equations are like “recipes” that
describe the ingredients and products of a
chemical reaction.
Plus sign means “reacts with”
K + O2
K2O
Reactants
Products
The arrow means “produces”
Chemical Equations
Chemical Equations
Word Equation:
Chemical Equations
Word Equation:
methane + oxygen
water + carbon dioxide
Chemical Equations
Word Equation:
methane + oxygen
Skeleton Equation:
water + carbon dioxide
Chemical Equations
Word Equation:
methane + oxygen
water + carbon dioxide
Skeleton Equation:
CH4 + O2
H2O
+
CO2
Chemical Equations
Word Equation:
methane + oxygen
water + carbon dioxide
Skeleton Equation:
CH4 + O2
H2O
+
CO2
Skeleton equations only show the formulas of the
reactants and products, not the correct
proportions of each. Why is that a problem?
Balancing Chemical Equations
Balancing Chemical Equations
• Chemical equations must obey the Law of
Conservation of Mass. This means we
need to balance the skeleton equation.
Balancing Chemical Equations
Steps and Rules for Balancing Equations
Balancing Chemical Equations
Steps and Rules for Balancing Equations
K + O2
K2O
Balancing Chemical Equations
Steps and Rules for Balancing Equations
K + O2
K2O
1. Start on the left – how many “K” atoms are on
the left side?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
K + O2
K2O
1. Start on the left – how many “K” atoms are on
the left side? ONE
Balancing Chemical Equations
Steps and Rules for Balancing Equations
K + O2
K2O
1. Start on the left – how many “K” atoms are on
the left side? ONE
2. Look on the other side of the arrow. How many
are on the other side?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
K + O2
K2O
1. Start on the left – how many “K” atoms are on
the left side? ONE
2. Look on the other side of the arrow. How many
are on the other side?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
K + O2
K2O
1. Start on the left – how many “K” atoms are on
the left side? ONE
2. Look on the other side of the arrow. How many
are on the other side? TWO
Balancing Chemical Equations
Steps and Rules for Balancing Equations
K + O2
K2O
1. Start on the left – how many “K” atoms are on
the left side? ONE
2. Look on the other side of the arrow. How many
are on the other side? TWO
3. NOTE!! You can NEVER write or change the
“little” numbers in equations
Balancing Chemical Equations
Steps and Rules for Balancing Equations
K + O2
K2O
4. To add more atoms you CAN write “big”
numbers (coefficients) in front of atoms. We
need two atoms of “K” on both sides of the arrow
so write a “2” on the left.
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
4. To add more atoms you CAN write “big”
numbers (coefficients) in front of atoms. We
need two atoms of “K” on both sides of the arrow
so write a “2” on the left.
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
5. Look at the next atom. Oxygen. How many are
there on the left side of the arrow?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
5. Look at the next atom. Oxygen. How many are
there on the left side of the arrow?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
5. Look at the next atom. Oxygen. How many are
there on the left side of the arrow? TWO
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
5. Look at the next atom. Oxygen. How many are
there on the left side of the arrow? TWO
6. How many are there on the right side of the
arrow?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
5. Look at the next atom. Oxygen. How many are
there on the left side of the arrow? TWO
6. How many are there on the right side of the
arrow?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
5. Look at the next atom. Oxygen. How many are
there on the left side of the arrow? TWO
6. How many are there on the right side of the
arrow? ONE
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
5. Look at the next atom. Oxygen. How many are
there on the left side of the arrow? TWO
6. How many are there on the right side of the
arrow? ONE - Ooops! We have a problem.
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
5. Look at the next atom. Oxygen. How many are
there on the left side of the arrow? TWO
6. How many are there on the right side of the
arrow? ONE - Ooops! We have a problem.
REMEMBER – we can’t write subscripts (little
numbers) only coefficients (big numbers)
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
K2O
7. The solution is to put a “2” in front of the K2O on
the right side. This gives you 2 oxygen.
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
2 K2O
7. The solution is to put a “2” in front of the K2O on
the right side. This gives you 2 oxygen.
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
2 K2O
7. The solution is to put a “2” in front of the K2O on
the right side. This gives you 2 oxygen.
But what has happened to the number of “K”
atoms on the right side?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
2 K2O
7. The solution is to put a “2” in front of the K2O on
the right side. This gives you 2 oxygen.
But what has happened to the number of “K”
atoms on the right side? How can you fix this?
Balancing Chemical Equations
Steps and Rules for Balancing Equations
2 K + O2
2 K2O
7. The solution is to put a “2” in front of the K2O on
the right side. This gives you 2 oxygen.
But what has happened to the number of “K”
atoms on the right side? How can you fix this?
8. Change the number of “K” on the left from 2 to 4.
Balancing Chemical Equations
Steps and Rules for Balancing Equations
4 K + O2
2 K2O
7. The solution is to put a “2” in front of the K2O on
the right side. This gives you 2 oxygen.
But what has happened to the number of “K”
atoms on the right side? How can you fix this?
8. Change the number of “K” on the left from 2 to 4.
Balancing Chemical Equations
Steps and Rules for Balancing Equations
Check how many are on each side
4 K + O2
2 K2O
Balancing Chemical Equations
Steps and Rules for Balancing Equations
Check how many are on each side
4 K + O2
2 K2O
_____ K _____
_____ O _____
Balancing Chemical Equations
Steps and Rules for Balancing Equations
Check how many are on each side
4 K + O2
2 K2O
_____ K _____
_____ O _____
Balancing Chemical Equations
Steps and Rules for Balancing Equations
Check how many are on each side
4 K + O2
2 K2O
_____ K _____
_____ O _____
Balancing Chemical Equations
Steps and Rules for Balancing Equations
Check how many are on each side
4 K + O2
2 K2O
_____ K _____
_____ O _____
Balancing Chemical Equations
Steps and Rules for Balancing Equations
Check how many are on each side
4 K + O2
2 K2O
_____ K _____
_____ O _____
Balancing Chemical Equations
Steps and Rules for Balancing Equations
Check how many are on each side
4 K + O2
2 K2O
_____ K _____
_____ O _____
Balancing Chemical Equations
Practice balancing these:
Li
+
PbO
H2
Br2
Pb
+
N2
LiBr
+
O2
NH3
Balancing Chemical Equations
Practice balancing these:
Balancing Chemical Equations
Practice balancing these:
Sn(NO2)4 + K3PO4
C2H6 +
O2
Mg(ClO4)2 +
KNO2 + Sn3(PO4)4
CO2
Na
+
H 2O
NaClO4 +
Mg