Formic acid (data page) explained

This page provides supplementary chemical data on formic acid.

Material Safety Data Sheet

The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source and follow its directions.

• MSDS from FLUKA in the SDSdata.org database
• Science Stuff

Structure and properties

	Structure and properties
Index of refraction, nD	1.3714 at 20 °C
Abbe number	?
Dielectric constant, εr	58.5 ε0 at 16 °C measured at 400 MHz
Bond strength	?
Bond length^[1]	C=O bond: 123 pm C–OH bond: 136 pm
Bond angle	?
Magnetic susceptibility	?
Surface tension	37.67 dyn/cm at 20 °C
Viscosity^[2]	2.2469 mPa·s at 10 °C 1.7844 mPa·s at 20 °C 1.2190 mPa·s at 40 °C 0.5492 mPa·s at 100 °C

Thermodynamic properties

	Phase behavior
Triple point	281.40 K (8.25 °C), 2.2 kPa
Critical point^[3]	588 K (315 °C), 5.81 MPa
Std enthalpy change of fusion, ΔfusH^o	+12.68 kJ/mol
Std entropy change of fusion, ΔfusS^o	+45.05 J/(mol·K) at 8.25 °C
Std enthalpy change of vaporization, ΔvapH^o	+23.1 kJ/mol
Std entropy change of vaporization, ΔvapS^o	+61.8 J/(mol·K)
	Solid properties
Std enthalpy change of formation, ΔfH^osolid	? kJ/mol
Standard molar entropy, S^osolid	? J/(mol K)
Heat capacity, cp	74.5 J/(mol K) at –22 °C 82.8 J/(mol K) at 0 °C
	Liquid properties
Std enthalpy change of formation, ΔfH^oliquid	–425.5 kJ/mol
Standard molar entropy, S^oliquid	129.0 J/(mol K)
Enthalpy of combustion, ΔcH^o	–254.6 kJ/mol
Heat capacity, cp	101.3 J/(mol K) at 20–100 °C
	Gas properties
Std enthalpy change of formation, ΔfH^ogas	–362.6 kJ/mol
Standard molar entropy, S^ogas	251.0 J/(mol K)
Heat capacity, cp	45.68 J/(mol K) at 25 °C

Vapor pressure of liquid

	P in mm Hg	1	10	40	100	400	760
	T in °C	–20.0(s)	2.1(s)	24.0	43.8	80.3	100.6

Table data obtained from CRC Handbook of Chemistry and Physics, 44th ed. The "(s)" notation indicates temperature of solid/vapor equilibrium. Otherwise the data is temperature of liquid/vapor equilibrium.

Distillation data

Vapor-liquid Equilibrium for Formic acid/Water^[4] P = 760 mmHg
BP Temp. °C	% by mole water
	liquid	vapor
102.3	4.05	2.45
104.6	15.5	10.2
105.9	21.8	16.2
107.1	32.1	27.9
107.6	40.9	40.2
107.6	41.1	40.5
107.6	46.4	48.2
107.1	52.2	56.7
106.0	63.2	71.8
104.2	74.0	83.6
102.9	82.9	91.7
101.8	90.0	95.1

Spectral data

	UV-Vis
λmax	? nm
Extinction coefficient, ε	?
	IR
Major absorption bands	? cm^−1
	NMR
Other NMR data
	MS
Masses of main fragments

Safety data

	Formic acid
EINECS number	200-579-1
	Safety data
EU classification	Corrosive (C)
PEL	5 ppm (9 mg/m^3)
IDLH	30 ppm
Autoignition temperature	520 °C
Explosive limits	18–51%

References

1. Morrison, Robert Thornton and Boyd, Robert Neilson, Organic Chemistry, 2nd ed. Allyn and Bacon 1972, p. 596
2. Lange's Handbook of Chemistry, 10th ed. pp. 1669–1674
3. Web site: Molecular Model for Formic Acid adjusted to Vapor-Liquid Equilibrium . Thornton Schnabel . Marfa Cortada . Jadran Vrabec . Santiago Lago . Hans Hasse . Institut für Technische Thermodynamik und Thermische Verfahrenstechnik (Institute for Technical Thermodynamic and Thermal Process Engineering), Universität Stuttgart . 3 May 2007 . https://web.archive.org/web/20070612031308/http://www.itt.uni-stuttgart.de/~schnabel/HCOOH.pdf . 12 June 2007 . dead .
4. Web site: Binary Vapor-Liquid Equilibrium Data. Chemical Engineering Research Information Center. Queriable database. 6 May 2007.

• Web site: Pure Component Properties. Chemical Information Research Information Center. 4 May 2007. https://web.archive.org/web/20020802222945/http://www.cheric.org/kdb/kdb/hcprop/showprop.php. 2 August 2002. dead.