1 normal acid or base (1N): Difference between revisions
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Biologists are sometimes confused by the non-standard[http://physics.nist.gov/cuu/Units/checklist.html] chemical unit of '''normality N'''. N refers in general to salts while it's most commonly used in the context of acid and bases. | Biologists are sometimes confused by the non-standard[http://physics.nist.gov/cuu/Units/checklist.html] chemical unit of '''normality N'''. N refers in general to salts while it's most commonly used in the context of acid and bases. N can refere to either the cation or the anion in a hydrolysis. In the context of acid and bases it is generally assumed that N refers to the proton or the hydroxide ion. | ||
* 1 M (mol/l) = 1 N for an acid that releases 1 proton* when dissolved in water, e.g. HCL (*monoprotic) | * 1 M (mol/l) = 1 N for an acid that releases 1 proton* when dissolved in water, e.g. HCL (*monoprotic) | ||
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== 1N, 2N HCl == | |||
1N HCl | |||
* 8.3 ml fuming HCl (37% v/v = ~12N = ~12M) | |||
* 91.7 ml H<sub>2</sub>O | |||
2N HCl, see also [http://www.ihcworld.com/_protocols/epitope_retrieval/hcl.htm] | |||
* 16.5 ml fuming HCl (37% v/v = ~12N = ~12M) | |||
* 83.5 ml H<sub>2</sub>O | |||
== Molarity (M) also a non-standard unit == | |||
For the nitpickers, ''molarity M'' is also a non-standard unit[http://physics.nist.gov/cuu/Units/checklist.html]. Expressing this explicitly as mol/L or mol/m<sup>3</sup> is clearer to readers less versed in current biological customs. | |||
==See also== | ==See also== | ||
* [http://en.wikipedia.org/wiki/Concentration#Normality Normality section of Concentration page at the Wikipedia] | * [http://en.wikipedia.org/wiki/Concentration#Normality Normality section of Concentration page at the Wikipedia] | ||
* [http://physics.nist.gov/cuu/Units/units.html International standard units, SI units] | * [http://physics.nist.gov/cuu/Units/units.html International standard units, SI units] | ||
* [http://www.histosearch.com/histonet/Dec03A/RE.HistonetnormalsolutionA.html Example student question & answer] | |||
[[Category:Chemical]] | [[Category:Chemical]] | ||
[[Category:Material]] | [[Category:Material]] | ||
[[Category:Acid]] | [[Category:Acid]] | ||
Latest revision as of 14:05, 27 February 2012
Biologists are sometimes confused by the non-standard[1] chemical unit of normality N. N refers in general to salts while it's most commonly used in the context of acid and bases. N can refere to either the cation or the anion in a hydrolysis. In the context of acid and bases it is generally assumed that N refers to the proton or the hydroxide ion.
- 1 M (mol/l) = 1 N for an acid that releases 1 proton* when dissolved in water, e.g. HCL (*monoprotic)
- 1 M (mol/l) = 2 N for an acid that releases 2 protons*, e.g. H2SO4 (*diprotic)
For example, some antigen retrieval methods use 2N hydrochloric acid to open up the tissue to allow antibody binding. This could be a nucleotide analogue, as BrdU or dUTP-TMR in cell proliferation of apoptosis assays.
| acid/case | molecular weight | N vs M |
|---|---|---|
| HCl -> 1·H+ + Cl- | 36.5 g/mol | 1N = 1M = 36.5g/L |
| H2SO4 -> 2·H+ + SO42- | 98 g/mol | 2N = 1M = 98g/L |
| NaOH -> Na+ + 1·OH- | 40 g/mol | 1N = 1M = 40g/L |
1N, 2N HCl
1N HCl
- 8.3 ml fuming HCl (37% v/v = ~12N = ~12M)
- 91.7 ml H2O
2N HCl, see also [2]
- 16.5 ml fuming HCl (37% v/v = ~12N = ~12M)
- 83.5 ml H2O
Molarity (M) also a non-standard unit
For the nitpickers, molarity M is also a non-standard unit[3]. Expressing this explicitly as mol/L or mol/m3 is clearer to readers less versed in current biological customs.
