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) = ''2'' N for an acid that releases 2 protons*, e.g. H<sub>2</sub>SO<sub>4</sub> (*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.
 
{| {{table}} OR border=1 cellpadding=5 cellspacing=0 OR {{sorttable}}
! style="background:lightgrey"|acid/case
! style="background:lightgrey"|molecular weight
! style="background:lightgrey"|N vs M
|-
| HCl -> <font color=blue>1·H<sup>+</sup></font> + Cl<sup>-</sup>
| 36.5 g/mol
| 1N = 1M = 36.5g/L
|-
| H<sub>2</sub>SO<sub>4</sub> -> <font color=blue>2·H<sup>+</sup></font> + SO<sub>4</sub><sup>2-</sup>
| 98 g/mol
| 2N = 1M = 98g/L
|-
| NaOH -> Na<sup>+</sup> + <font color=blue>1·OH<sup>-</sup></font>
| 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 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==
* [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://www.histosearch.com/histonet/Dec03A/RE.HistonetnormalsolutionA.html Example student question & answer]
 
[[Category:Chemical]]
[[Category:Material]]
[[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.

See also

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