balancing chemical reactions

BalancingBalancingChemical ReactionsChemical Reactions

Why?Why?

There are laws!!!!There are laws!!!!

Matter cannot be created or Matter cannot be created or destroyed only changed. So if you destroyed only changed. So if you start with 20 hydrogen, you end start with 20 hydrogen, you end up with 20 hydrogenup with 20 hydrogen

EquationsEquations

Vinegar + Baking SodaVinegar + Baking Soda White Powder + Clear Liquid + Bubbles

Reactants Products

HC2H3O2 + NaHCO3 NaC2H3O2 + H2O + CO2

Word Equation

Formula Equation

Balancing a FormulaBalancing a Formula

HC2H3O2 + NaHCO3 NaC2H3O2 + H2O + CO2

HCCHHHOO + NaHCOOO NaCCHHHOO + HHO + COO

(5H, 3C, 5O, Na)

14 atoms

(5H, 3C, 5O, Na)

14 atoms

Balanced?Balanced?

Ag + HAg + H22SS AgAg22S + HS + H22Ag, 2H, S 2Ag, 2H, S

Ag + HAg + H22SS AgAg22S + HS + H22

2Ag, 2H, S 2Ag, 2H, S

If not….The ONLY thing you can do is multiply the number of MOLECULES you have. You do this by putting a

coefficient in front of the MOLECULE.2

The 2 multiplies everything after it until you have a different molecule.

Balance the followingBalance the following Na + HNa + H22O O NaOH + H NaOH + H22

Na=Na= Na=Na=

H =H = H =H =

O =O = O = O =

12

13

1

1

BALANCED

2

2

2

44

2Step 1: list all the elements underneath the reactants and products

22

2

Step 2: Count how many atoms of each element are on the reactant side and the product side

3rd Step: Put numbers (coefficients like 1, 2, 3, 4, 5 etc..) in front of the compounds that you are short on. This multiplies all of the atoms in the compound. When you do that, you may have to change the other side as well.

Why is it 4? Because 2 H from NaOH and 2 H from H2 are added

So what do we need to do?

Balance the followingBalance the following

HH22O + OO + O22 H H22OO22

H =H = H =H =

O =O = O = O =

23 2

2

So what do we need to do?

2

44

2

44

BALANCED

Step 1: list all the elements underneath the reactants and products

Step 2: Count how many atoms of each element are on the reactant side and the product side

3rd Step: Put numbers (coefficients like 1, 2, 3, 4, 5 etc..) in front of the compounds that you are short on. This multiplies all of the atoms in the compound. When you do that, you may have to change the other side as well.

Why did I put the 2 in front of H2O instead of O2?

Because only changing O2

would not help me with the H.

CaClCaCl22 Ca Ca22 + Cl + Cl22Ca=Ca= Ca=Ca=

Cl =Cl = Cl =Cl =21

22

42

4

2 2

BALANCED

Al + NaOH Al + NaOH Na Na33AlOAlO33 + H + H22

Al=Al= Al=Al=

Na=Na= Na =Na =

O =O = O =O =

H =H = H =H =

11

11

31

23

2

4

BALANCED

2

636

3

3

3 22

44

4

6

34

2

66

6

6

Now you do some at your deskNow you do some at your desk

Zn + HCl Zn + HCl ZnCl ZnCl22 + H + H22

Al + OAl + O22 Al Al22OO

Zn + Zn + HCl HCl ZnCl ZnCl22 + H + H22

Zn=Zn= Zn=Zn=

H=H= H =H =

Cl =Cl = Cl = Cl =

1

122

1

2

BALANCED

1 22

Al + OAl + O22 Al Al22OO

Al=Al= Al=Al=

O =O = O =O =

2

11

4 2

4

BALANCED

2

42

1.1. Zn + Zn + 22HCl HCl ZnCl ZnCl22 + H + H22

2.2. 1212Al + 3OAl + 3O22 66AlAl22OO