Page 12 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

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

Mole Concept

• Molecules and atoms are extremely small objects - both in size and mass.

• The mole is a standard scientific unit for measuring quantities of very small
entities such as atoms or molecules.

• 1 Mole 6.022 × 10 23
AVOGADRO’S NUMBER
(Atoms/Molecules/… )

23
• 3 Moles 3 × 6.022 × 10
• It is also equal to the formula weight (atomic or molecular) of a substance
expressed in grams.

Note:
• weight = mass
• for atoms: it is termed atomic weight or atomic
mass
• for molecules: it is termed molecular weight or
molecular mass
• Notice that: Na, K, are atoms, H2O, N2, H2SO4
are molecules.
▪ Formula or molecular weight: The sum of the atomic weights of the atoms

that make up a compound.

• e.g. MW of NaOH = 23 + 16 + 1 = 40 g

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