Normality: Difference between revisions
imported>David E. Volk No edit summary |
imported>Paul Wormer (Avogadro [6.02 not 6.23]; equivalent weight; typo.) |
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In [[chemistry]], '''normality''' (N) is a term used to indicate chemical concentrations that is typically only used for [[acid]]-[[base]] reactions. A 1 normal (1 N) solution of any acid can neutralize an equal volume of any 1 N base | In [[chemistry]], '''normality''' (N) is a term used to indicate chemical concentrations that is typically only used for [[acid]]-[[base]] reactions. A 1 normal (1 N) solution of any acid can neutralize an equal volume of any 1 N base solution. A one liter volume of a 1 N acid solution will neutralize one [[mole (unit)|mole]], or about 6.02⋅10<sup>23</sup> ([[Avogadro's number]]) hydroxide ions OH<sup>−</sup>. Normality is always greater than or equal to the related concentration unit [[molarity]], such that | ||
:<math> \mathbf{N} = \mathbf{n} \times \mathbf{M} </math> | :<math> \mathbf{N} = \mathbf{n} \times \mathbf{M} </math> | ||
where | where n is an integer greater than or equal to 1. In acid-base reaction n is the number of protons (forming H<sub>3</sub>O<sup>+</sup>) donated by one molecule of the acid. The [[molecular weight]] divided by n is the [[equivalent weight]]. | ||
For a monoprotic acid like [[hydrochloric acid]], HCl, which can provide only 1 mole of protons ( [[hydronium ion]]s, H<sub>3</sub>O<sup>+</sup>) per mole of acid, | For a monoprotic acid like [[hydrochloric acid]], HCl, which can provide only 1 mole of protons ( [[hydronium ion]]s, H<sub>3</sub>O<sup>+</sup>) per mole of acid, 1 M = 1 N. A diprotic acid like [[sulfuric acid]], H<sub>2</sub>SO<sub>4</sub>, provides two moles of protons per mole of acid (n=2) and thus a 1 M solution of sulfuric acid is a 2 N solution. | ||
Revision as of 10:08, 1 September 2009
In chemistry, normality (N) is a term used to indicate chemical concentrations that is typically only used for acid-base reactions. A 1 normal (1 N) solution of any acid can neutralize an equal volume of any 1 N base solution. A one liter volume of a 1 N acid solution will neutralize one mole, or about 6.02⋅1023 (Avogadro's number) hydroxide ions OH−. Normality is always greater than or equal to the related concentration unit molarity, such that
where n is an integer greater than or equal to 1. In acid-base reaction n is the number of protons (forming H3O+) donated by one molecule of the acid. The molecular weight divided by n is the equivalent weight.
For a monoprotic acid like hydrochloric acid, HCl, which can provide only 1 mole of protons ( hydronium ions, H3O+) per mole of acid, 1 M = 1 N. A diprotic acid like sulfuric acid, H2SO4, provides two moles of protons per mole of acid (n=2) and thus a 1 M solution of sulfuric acid is a 2 N solution.