Calculation of Normality

Equivalent weight (EW) = Molecular weight (MW) / Valencey. (Z)

Normality (N) = Equivalent weight (EW) / Volume of Solution (1000 ml.)

Meq = Actual weight (W) / Equivalent weight (EW)

Example:Molecular wt of K2Cr2O7 is 294.148 gm

Valency = 6 (because of Cr -6)

EW = 294.148/6 = 49.025

N = 49.025/1000 ml = 0.049025.

To make 0.25 N solution = 0.25 x EW

= 0.25 x 49.025 = 12.256 gm. of K2Cr2O7 is required.

Molarity = Molecular Weight, grams / One Liter of Distilled Water

Example:

1 M NaCl = 58.5 gm NaCl in 1 Liter of D.W = 58500 mg/Liter

0.5 M NaCl = 29250 mg/Liter toxic for Bacteria

 

Author: T.P.Sivanandan


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