# 1 normal acid or base (1N)

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 Revision as of 12:52, 8 December 2010 (view source) (recipes for 1N 2N HCl)← Previous diff Current revision (17:05, 27 February 2012) (view source) (→1N, 2N HCl) Line 26: Line 26: == 1N, 2N HCl == == 1N, 2N HCl == 1N HCl 1N HCl - * 10 ml fuming HCl (37% v/v = 10N = 10M) + * 8.3 ml fuming HCl (37% v/v = ~12N = ~12M) - * 90 ml H2O + * 91.7 ml H2O 2N HCl, see also [http://www.ihcworld.com/_protocols/epitope_retrieval/hcl.htm] 2N HCl, see also [http://www.ihcworld.com/_protocols/epitope_retrieval/hcl.htm] - * 20 ml fuming HCl (37% v/v = 10N = 10M) + * 16.5 ml fuming HCl (37% v/v = ~12N = ~12M) - * 80 ml H2O + * 83.5 ml H2O == Molarity (M) also a non-standard unit == == Molarity (M) also a non-standard unit ==

## Current revision

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.