Editing Formic acid (section)

==Properties==
[[File:Formic Acid Hydrogenbridge V.1.svg|thumb|left|Cyclic dimer of formic acid; dashed <span style="color:green;">'''green'''</span> lines represent hydrogen bonds]]
Formic acid is a colorless liquid having a pungent, penetrating odor<ref>{{cite web|url=https://www.osha.gov/chemicaldata/chemResult.html?recNo=468|title=OSHA Occupational Chemical Database – Occupational Safety and Health Administration|website=osha.gov|access-date=17 April 2015|archive-date=29 April 2021|archive-url=https://web.archive.org/web/20210429045534/https://www.osha.gov/chemicaldata/chemResult.html?recNo=468|url-status=dead}}</ref> at room temperature, comparable to the related [[acetic acid]]. Formic acid is about ten times stronger than [[acetic acid]] having a (logarithmic) dissociation constant of 3.745 compared to 4.756 for acetic acid.<ref name="Smith R"/>

It is [[Miscibility|miscible]] with water and most polar [[organic chemistry|organic]] [[solvent]]s, and is somewhat soluble in [[hydrocarbon]]s. In hydrocarbons and in the vapor phase, it consists of [[Hydrogen bond|hydrogen-bond]]ed [[dimer (chemistry)|dimers]] rather than individual molecules.<ref name=Ullmann_2009>{{cite book |doi=10.1002/14356007.a12_013 |chapter=Formic Acid |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2000 |last1=Reutemann |first1=Werner |last2=Kieczka |first2=Heinz |isbn=978-3-527-30673-2 }}</ref><ref name=Balabin_2009>{{cite journal |doi=10.1021/jp9002643 |pmid=19344174 |title=Polar (Acyclic) Isomer of Formic Acid Dimer: Gas-Phase Raman Spectroscopy Study and Thermodynamic Parameters |journal=The Journal of Physical Chemistry A |volume=113 |issue=17 |pages=4910–8 |year=2009 |author= Roman M. Balabin |bibcode=2009JPCA..113.4910B }}</ref> Owing to its tendency to hydrogen-bond, gaseous formic acid does not obey the [[ideal gas law]].<ref name=Balabin_2009/> Solid formic acid, which can exist in either of two [[polymorphism (materials science)|polymorphs]], consists of an effectively endless network of hydrogen-bonded formic acid molecules. Formic acid forms a high-boiling [[azeotrope]] with water (107.3&nbsp;°C; 77.5% formic acid). Liquid formic acid tends to [[supercooling|supercool]].
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