Equivalent concentration
In chemistry, the equivalent concentration or normality (N) of a solution is defined as the molar concentration ci divided by an equivalence factor or n-factor feq:
Definition
Normality is defined as the number of
Usage
There are three common types of chemical reaction where normality is used as a measure of reactive species in solution:
- In value. Each solute can produce one or more equivalents of reactive species when dissolved.
- In redox reactions, the equivalence factor describes the number of electrons that an oxidizing or reducing agent can accept or donate. Here, 1/feq can have a fractional (non-integer) value.
- In precipitation reactions, the equivalence factor measures the number of ions which will precipitate in a given reaction. Here, 1/feq is an integer value.
Normal concentration of an ionic solution is also related to conductivity (electrolytic) through the use of equivalent conductivity.
Medical
Although losing favor in the medical industry, reporting of serum concentrations in units of "eq/L" (= 1 N) or "meq/L" (= 0.001 N) still occurs.
Examples
Normality can be used for acid-base titrations. For example,
- feq(H2SO4) = 0.5
If the concentration of a sulfuric acid solution is c(H2SO4) = 1 mol/L, then its normality is 2 N. It can also be called a "2 normal" solution.
Similarly, for a solution with c(H3PO4) = 1 mol/L, the normality is 3 N because phosphoric acid contains 3 acidic H atoms.
Criticism of the term "normality"
Normality is an ambiguous measure of the
See also
- Equivalent (chemistry)
- Normal saline, a solution of NaCl, but not a normal solution. Its normality is about 0.154 N.
References
- ISBN 0-86542-6155. section 6.3. "Archived copy" (PDF). Archived from the original (PDF) on July 26, 2011. Retrieved 2009-05-10.)
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: CS1 maint: archived copy as title (link
External links
- Analytical Chemistry 2.1, by David Harvey (Open-source Textboox) | Chapter 16.1: Normality
- Normality: Definition, formula, equations, type, example,.[1]
- ^ "Normality | Definition, Formula, Equations, Type, Example". 2022-11-09. Retrieved 2023-01-29.