Formic acid (data page)

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.

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, ΔfusHo		 +12.68 kJ/mol
Std entropy change
of fusion, ΔfusSo		 +45.05 J/(mol·K) at 8.25 °C
Std enthalpy change
of vaporization, ΔvapHo		 +23.1 kJ/mol
Std entropy change
of vaporization, ΔvapSo		 +61.8 J/(mol·K)
Solid properties
Std enthalpy change
of formation, ΔfHosolid		 ? kJ/mol
Standard molar entropy,
Sosolid		 ? 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, ΔfHoliquid		 –425.5 kJ/mol
Standard molar entropy,
Soliquid		 129.0 J/(mol K)
Enthalpy of combustion, ΔcHo –254.6 kJ/mol
Heat capacity, cp 101.3 J/(mol K) at 20–100 °C
Gas properties
Std enthalpy change
of formation, ΔfHogas		 –362.6 kJ/mol
Standard molar entropy,
Sogas		 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.

log10 of formic acid vapor pressure. Uses formula: \scriptstyle \log_{10} P_{mmHg} = 6.94459 - \frac {1295.26} {218.0+T} obtained from Lange's Handbook of Chemistry, 10th ed.

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
Proton NMR  
Carbon-13 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/m3)
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. ↑ Thornton Schnabel, Marfa Cortada, Jadran Vrabec, Santiago Lago, Hans Hasse. "Molecular Model for Formic Acid adusted to Vapor-Liquid Equilibrium" (PDF). Insitut für Technische Thermodynamik und Thermische Verfahrenstechnik (Institute for Technical Thermodynamic and Thermal Process Engineering), Universität Stuttgart. Retrieved 3 May 2007.
  4. ↑ "Binary Vapor-Liquid Equilibrium Data" (Queriable database). Chemical Engineering Research Information Center. Retrieved 6 May 2007.

Except where noted otherwise, data relate to standard ambient temperature and pressure.

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