Komar University of Science and Technology
Pharmacy Orientation and Calculation II
Milliequivalents,Millimoles, and Milliosmoles
Outline
• Milliequivalents ✓
• Millimoles
• Osmolarity
Learning objectives
• Calculate problems involving millimoles
Millimoles
• Mole is the molecular weight of a substance in grams.
• Example: Atomic weight of Iron: 56; 1 mole of iron= 56 g.
• Subdivision of Mole: I mole contains 1000 millimoles.
• A millimole is 1/1000 of the molecular weight in grams.
• Millimolar conversions do not take into account the valence of an
electrolyte as do milliequivalent conversions.
The International System (SI)
• Millimoles per litre (mmol/L) to express the concentration of
electrolytes in representing the combining power of a chemical
species.
• For monovalent species, the numeric values of the milliequivalent
and millimole are identical.
Monovalent Species
✓
✓
✓
✓
Example 1
How many millimoles of monobasic sodium phosphate NaHPO4
(m.w. 138) are present in 100 g of the substance?
NaHPO4= 138 g/mole
1 mole=138 g
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X= 0.725 moles,=725mmol
Example 2
• How many milligrams would 1 mmol of monobasic sodium
phosphate (M.W. 138) weigh?
1 mole= 138g
1 mmol=
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molecular weight in grams;
1mmol= 0.138 g
X=138mg
For further elaboration:
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= 138 mg/ mmol
Example 3
• What is the weight, in milligrams, of 1 mmol of HPO4= ?
Atomic weight of HPO4= 95.98
1 mole of HPO4= 95.98 g
1 mmol of HPO4= 1/1000 X molecular weight in grams;
1/1000 X 95.98 g = 0.09598 g
= 95.98 mg
• To be continued ….