Page 23 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

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

Coefficients & Subscripts:

numbers in front of reactant or product
Coefficients
that represents the number of moles.

lower, smaller numbers that define the

Subscripts number of atoms in the formula of a

compound.

Notes

• During a chemical reaction, atoms are rearranged,

not created nor destroyed!

• According to Law of conservation of mass:

Matter can neither be created nor destroyed.

• When chemicals are reacted in a closed container, the

mass before and after the reaction is the same.

• Chemical equations must be balanced to show the
relative amounts of all substances.

• Balanced: means each side of the equations has the
same number of atoms of each element.

CH4 + O2 → H2O + CO2 Unbalanced

CH4 + 2O2 → 2H2O + CO2 Balanced

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