# Interchanging of Molarity and Normality Concentrations

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Interchanging of Molarity and Normality Concentrations

When working in the histology laboratory, it may be helpful at times to simply convert an existing concentration of substance to another type of concentration to meet the reagent needs of a procedure. The interconversion of molarity and normality sometimes needs to be performed by the histotechnician.
Example:
A 3M solution of NaOH is found on the supply room shelf. The histotechnician is curious what the normality would be for that solution, as she needs 2N NaOH. What is the normality of the 3M NaOH solution?
When doing normal/molar conversions, remember when the valence is one, normality and molarity are the same.
Valence of NaOH = 1
Normality = valence x molarity
N = 1 x 3M = 3
N = 3
The normality of the 3M solution of NaOH is 3N.
Example:
Given a 4N solution of H2SO4, a histotechnologist needs to quickly know the molarity of this solution.
Valence of H2SO4 = 2
Molarity = normality / valence
M = 4/2
M = 2
The molarity of a 4N solution of H2SO4 is 2M.