Page 24 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

Balancing Chemical Equations
• In order to balance chemical equations:

1) Write correct formulas for all reactants and products.

2) Count the number of atoms of each element in reactants & products.

3) Balance one at a time using coefficients.

4) Check for balance.

5) Are the coefficients in the lowest possible ratio?

6) Order preferred: (C → H → O)

• NOTE: When balancing equations, you may change coefficients as much as

you need to, but you may NEVER change subscripts. Why???

• Counting Atoms - Multiply coefficient by subscript of each element.

• If in parenthesis, the subscript after the parenthesis is multiplied to

everything in the parenthesis then multiplied by coefficient.

2CrCl Ba(OH) 3Ca(ClO )
3 2 3 2

Cr : (2x1) = 2 Ba : 1 Ca : (3x1) = 3

Cl : (2 x 3) = 6 O : (2x1) = 2 Cl : (2 x 3) = 6

H : (2 x 1) = 2 O : (3 x 3 x 2) = 18

How to balance an equation?

Step 1: Create a R.A.P table Na + O → Na O
2 2 2
What’s a R.A.P table ?? #R Atom #P

R → Reactants 1 Na 2

A → Atom 2 O 2

P → Product

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