Page 14 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

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

Example 2

How many moles are contained in 36 g of water?
(atomic weights H=1, O=16).

- One mole is the molecular weight expressed in grams.
- One mole of H O = (2×1) + 16 = 18 g
2
1 Mole 18 g

?? Mole 36 g
No. of moles = (36×1)/18 = 2 moles

Example 1

Determine the number of molecules of H2O in 3 moles H2O

23
1 mole H O = 6.022 X 10 molecules H O
2 2
23
3 moles H O contains: 3 x 6.022 X 10 molecules H O
2 2
23
3 moles H O = 18.066 X 10 molecules H O
2 2

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