Flammable. With water , ethanol , ether and glycerol arbitrary miscible with most polar organic solvents , in hydrocarbons also have some solubility.
Relative density (d204) 1.220. Refractive index
1.3714 . Heat of combustion 254.4 kJ / mol, the critical temperature 306.8 ℃, critical pressure 8.63 MPa. Flash point of 68.9 ℃ ( open cup ) . Density of 1.22 , 1.59 Relative vapor density (air = 1 ) , the saturated vapor pressure (24 ℃) 5.33 kPa.
High concentrations of formic acid in the winter easy to freeze.
Incompatibility: Strong oxidizers , strong alkalis, reactive metal powders.
Hazardous characteristics: its vapor and air can form explosive mixtures case of fire , high- heat combustion caused the explosion. May react with strong oxidizing agents .
Solubility: miscible with water insoluble hydrocarbons , soluble in alcohol.
And the gas in hydrocarbons , the carboxylic acid to form a dimer through hydrogen bonding occurs . In gaseous hydrogen bonds lead to the existence of a large deviation between the acid gas and the ideal gas equation of state . Formic acid by the liquid and solid continuous acid through hydrogen bonding molecules .
Catalytic decomposition of formic acid in concentrated sulfuric acid to CO and H2O:
Due to the special structure of formic acid , one of its hydrogen atoms and carboxyl groups directly connected. Is a hydroxyl group can also be seen as formaldehyde. Therefore, formic acid and formaldehyde , and both properties.
Unlike most other carboxylic acid having the same properties , although not usually an acid chloride or acid anhydride. Acid dehydration decomposition of carbon monoxide and water. Carboxylic acid having reducing aldehydes like . It can play silver mirror reaction, the reduction of silver ions in the ammonia complex silver ions to metallic silver , while he is oxidized into carbon dioxide and water :
Formic acid is the only olefin addition reaction and a carboxylic acid . Carboxylic acid under the action of an acid ( such as sulfuric acid , hydrofluoric acid ) , and the rapid reaction of the olefin ester . However, a side reaction similar to the Koch reaction can also occur , is a more advanced product of a carboxylic acid .
Octanol / water partition coefficient : -0.54 , explosive limit % (V / V): 57.0, lower explosive limit % (V / V): 18.0.
Formic acid is a strong reducing agent , the silver mirror reaction can occur . Saturated fatty acids in the most acidic dissociation constant of 2.1 × 10-4. At room temperature slowly decomposed into carbon monoxide and water. And concentrated sulfuric acid heated to 60 ~ 80 ℃, decompose to release carbon monoxide . Formic acid is heated to above 160 ℃ decomposition that emit carbon dioxide and hydrogen. Alkali metal salts of formic acid was heated to 400 ℃ generated oxalate .
Molecular structure data
1 , the molar refractive index: 8.40
2 , molar volume (m / mol): 39.8
3 , parachor (90.2K): 97.5
4, the surface tension (dyne / cm): 35.8
5 , the polarization ratio (10cm): 3.33