Balancing Equations

Balancing EquationsBalancing Equations

Balancing, Writing, and Balancing, Writing, and Naming EquationsNaming Equations

Balancing EquationsBalancing Equations Law of Conservation Law of Conservation

of Matter:of Matter: In a chemical In a chemical

reaction, matter can reaction, matter can be neither created be neither created nor destroyed.nor destroyed.

In a chemical In a chemical reaction, the amount reaction, the amount of reactants equal of reactants equal the amount of the amount of products.products.

Balancing EquationsBalancing Equations Paraphrase:Paraphrase: Law of Conservation Law of Conservation

of of AtomsAtoms:: The number of atoms The number of atoms

of each type of of each type of element must be the element must be the same on each side of same on each side of the equation.the equation.


Hydrogen and oxygen are diatomic Hydrogen and oxygen are diatomic elements.elements.

Their subscripts cannot be changed.Their subscripts cannot be changed. The subscripts on water cannot be The subscripts on water cannot be

changed.changed.

Hydrogen + oxygen Hydrogen + oxygen waterwater

HH22 + O + O22 H H22OO

Balancing EquationBalancing Equation

Count the atoms on each side.Count the atoms on each side. Reactant side: 2 atoms H and 2 atoms OReactant side: 2 atoms H and 2 atoms O Product side: 2 atoms H and 1 atom OProduct side: 2 atoms H and 1 atom O

HH2 2 + O+ O22 H H22OO

Balancing EquationsBalancing Equations HH2 2 + O+ O22 H H22OO

If the subscripts cannot be altered, If the subscripts cannot be altered, how can the atoms be made how can the atoms be made equal?equal?

Adjust the number of molecules by Adjust the number of molecules by changing the changing the coefficientscoefficients. .


Reactants: 2 atoms of H and 2 Reactants: 2 atoms of H and 2 atoms of Oatoms of O

Products: 4 atoms of H and 2 Products: 4 atoms of H and 2 atoms of Oatoms of O

H is no longer balanced!H is no longer balanced!

HH22 + O + O22 22HH22OO


Reactant side: 4 atoms of H and 2 atoms of Reactant side: 4 atoms of H and 2 atoms of OO

Product side: 4 atoms of H and 2 atoms of OProduct side: 4 atoms of H and 2 atoms of O It’s Balanced!It’s Balanced!

22HH22 + O + O22 22HH22OO


Count atoms.Count atoms. Reactants: 2 atoms N and 2 atoms HReactants: 2 atoms N and 2 atoms H Products: 1 atom N and 3 atoms of NHProducts: 1 atom N and 3 atoms of NH33

NN22 + H + H22 NH NH33

Nitrogen + hydrogen ammoniaNitrogen + hydrogen ammonia

Balancing EquationsBalancing Equations Nothing is balanced.Nothing is balanced. Balance the nitrogen first by placing Balance the nitrogen first by placing

a coefficient of 2 in front of the NHa coefficient of 2 in front of the NH33..

NN22 + H + H22 22NHNH33

Balancing EquationsBalancing Equations Hydrogen is not balanced.Hydrogen is not balanced. Place a 3 in front of HPlace a 3 in front of H2.2.

Reactant side: 2 atoms N, 6 atoms HReactant side: 2 atoms N, 6 atoms H Product side: 2 atoms N, 6 atoms HProduct side: 2 atoms N, 6 atoms H

NN22 + + 33HH22 22NHNH33


Count atoms.Count atoms. Reactants: Ca – 3 atoms, P – 2 Reactants: Ca – 3 atoms, P – 2

atoms, O – 8 atoms; H – atoms, S – atoms, O – 8 atoms; H – atoms, S – 1 atom, O – 4 atoms1 atom, O – 4 atoms

CaCa33(PO(PO44))22 + H + H22SOSO44 CaSOCaSO44 + H + H33POPO44

Balancing EquationsBalancing Equations Side note on CaSide note on Ca33(PO(PO44))22

The subscript after the The subscript after the phosphate indicates two phosphate indicates two phosphate groups.phosphate groups.

This means two POThis means two PO443-3- groups with groups with

two P and eight O atoms.two P and eight O atoms.


CaCa33(PO(PO44))22 + H + H22SOSO44 CaSOCaSO4 4 + H + H33POPO44

Count atoms in the product.Count atoms in the product. Ca atoms – 1, S atom – 1, O atoms – Ca atoms – 1, S atom – 1, O atoms –

4; H atoms – 3, P atom – 1, O atoms - 4; H atoms – 3, P atom – 1, O atoms - 44

Balancing EquationsBalancing Equations In this equation, the ion groups do In this equation, the ion groups do

not break up.not break up. Instead of counting individual atoms, Instead of counting individual atoms,

ion groups may be counted.ion groups may be counted.




Reactants: CaReactants: Ca2+2+ – 3, PO – 3, PO443- 3- - 2, H- 2, H++ – 2, – 2,

SOSO442+ 2+ - 1- 1

Products: CaProducts: Ca2+2+ - 1, SO - 1, SO442- 2- - 1, H- 1, H++ - 3, PO - 3, PO44

3-3- - 1- 1

Balancing EquationsBalancing Equations Balance the metal first by placing a Balance the metal first by placing a

coefficient of 3 in front of CaSOcoefficient of 3 in front of CaSO44.. Products: Ca – 3 atoms, SOProducts: Ca – 3 atoms, SO44

2-2- - 3 - 3 groupsgroups

CaCa33(PO(PO44))22 + H + H22SOSO44 33CaSOCaSO4 4 + H + H33POPO44

Balancing EquationsBalancing Equations Three sulfate groups are needed on the reactant Three sulfate groups are needed on the reactant

side so place a coefficient of 3 in front of Hside so place a coefficient of 3 in front of H22SOSO44.. 3H3H22SOSO44 gives 6 H gives 6 H++ and 3 SO and 3 SO44

2-2-.. Neither phosphate nor calcium is balanced.Neither phosphate nor calcium is balanced.

CaCa33(PO(PO44))22 + + 33HH22SOSO44 33CaSOCaSO4 4 + H + H33POPO44

Balancing EquationsBalancing Equations A coefficient of 2 placed in front A coefficient of 2 placed in front

of Hof H33POPO44 which balances both which balances both hydrogen and phosphate.hydrogen and phosphate.

CaCa33(PO(PO44))22 + + 33HH22SOSO44 33CaSOCaSO4 4 + + 22HH33POPO44


The sulfate group breaks up. Each atom The sulfate group breaks up. Each atom must be counted individually. Ugh!must be counted individually. Ugh!

Reactants: Cu – 1, H – 2, S – 1, O – 4Reactants: Cu – 1, H – 2, S – 1, O – 4 Products: Cu – 1, S – 1, O - 4, H – 2, O – Products: Cu – 1, S – 1, O - 4, H – 2, O –

1, S – 1, O - 21, S – 1, O - 2

Cu + HCu + H22SOSO44

CuSOCuSO4 4 + H + H22O + SOO + SO22

Balancing EquationsBalancing Equations Sulfur is not balanced.Sulfur is not balanced. Place a two in front of sulfuric acid.Place a two in front of sulfuric acid. Count atoms: 2 HCount atoms: 2 H22SOSO44 H – 4, S – 2, O - H – 4, S – 2, O -

88

Cu + Cu + 22HH22SOSO44

CuSOCuSO44 + H + H22O + SOO + SO22

Balancing EquationsBalancing Equations Hydrogen needs to be balanced Hydrogen needs to be balanced

so place a 2 in front of the Hso place a 2 in front of the H22O. O. Count the number of atoms.Count the number of atoms.


CuSOCuSO44 + + 22HH22O + SOO + SO22

Balancing EquationsBalancing Equations Reactants: Cu – 1, H – 4, S – 2, O – 8Reactants: Cu – 1, H – 4, S – 2, O – 8 Products: Cu – 1, S – 1, O – 4, H – 4, Products: Cu – 1, S – 1, O – 4, H – 4,

O – 2, S – 1, O – 2 = Cu – 1, S – 2, H O – 2, S – 1, O – 2 = Cu – 1, S – 2, H – 4, O – 8– 4, O – 8

It’s balanced!It’s balanced!



Balancing EquationsBalancing Equations Balancing hints:Balancing hints:

Balance the metals first.Balance the metals first. Balance the ion groups next.Balance the ion groups next. Balance the other atoms.Balance the other atoms. Save the non ion group oxygen Save the non ion group oxygen

and hydrogen until the end.and hydrogen until the end.

Balancing EquationsBalancing Equations This method of This method of

balancing balancing equations is equations is the inspection the inspection method.method.

The method is The method is trial and error.trial and error.

Practice.Practice.

Writing and NamingWriting and Naming

Write the corresponding formula Write the corresponding formula equation and then balance the equation and then balance the equation.equation.

Nickel + hydrochloric acid Nickel + hydrochloric acid

Nickel(II) chloride + hydrogenNickel(II) chloride + hydrogen

Writing and NamingWriting and Naming Write each formula independently.Write each formula independently. Ignore the rest of the equation.Ignore the rest of the equation. Balance the equation after writing Balance the equation after writing

the formulasthe formulas..

Ni + HCl NiClNi + HCl NiCl22 + H + H22

Ni + Ni + 22HCl NiClHCl NiCl22 + H + H22

Writing and NamingWriting and Naming Remember the diatomic elements: Remember the diatomic elements:

HH22, N, N22, O, O22, F, F22, Cl, Cl22, Br, Br22, and I, and I2.2.


Balance the formula equation.Balance the formula equation. Write the word equation.Write the word equation.

Cu + HCu + H22SOSO44

CuSOCuSO44 + H + H22O + SOO + SO22

Writing and NamingWriting and Naming Cu + Cu + 22HH22SOSO44


Write the names:Write the names: Cu by itself is just Cu by itself is just coppercopper. Copper(I) . Copper(I)

or copper(II) would be incorrect.or copper(II) would be incorrect. HH22SOSO44 should be named as an acid. should be named as an acid. Sulfuric acidSulfuric acid

Writing and NamingWriting and Naming CuSOCuSO44 has a SO has a SO44

2-2- group so Cu must group so Cu must be 2+. Some metals must have be 2+. Some metals must have Roman Numerals. Roman Numerals. Copper(II) Copper(II) sulfatesulfate

HH22O is known as O is known as waterwater.. SOSO22 is a nonmetal compound. Its is a nonmetal compound. Its

name is either name is either sulfur dioxidesulfur dioxide or or sulfur(IV) oxidesulfur(IV) oxide..


Copper + sulfuric acid Copper + sulfuric acid Copper(II) sulfate + water + Copper(II) sulfate + water +

sulfur dioxidesulfur dioxide



Balancing EquationsBalancing Equations Practice!Practice! Practice!Practice! Practice!Practice!

Balancing Equations

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