Physical Properties

Formic acid usually found in nature the form is liquid. The color of formic acid is colorless, with the odor is sting and its corrosive to metal. molecular weight is 46.025 g/mol

Its density is 1.22 g/mL, melting point is 8.4 °C or 47.1 °F and boiling point is 101 °C or 213.3 °F at 760mmHg, flash point from formic acid is 69°C or 156°F .

• Has a great solubility because formic acid contains hydroxyl groups. Hydroxyl group (-OH) can form hydrogen bonding with water molecules. formic acid's solubility is greater than or equal to 100 mg/mL at 70°F.
• Water solubility from formic acid is 1000000 mg/L (at 25°C or in the standard pressure.
• Among the other of carboxylic acid groups, formic acid is the most soluble in water. Because, there's not alkyl chain in formic acid. The alkyl chain is hydrophobic (dislikes water).
• Formic acid is soluble in aseton and cold water. Miscible with acetone, ethyl acetate, methanol, ethanol and partially soluble in benzene, toluene, and xylenes.
  

Vapor density is 1,59 and vapor pressure is 35 mmHg at 68°F; 200mmHg at 142,5°F.

Viscosity from formic acid is 1.607mPas at 25°C.

Formic acid is polar.

The taste of formic acid is sour.

For formic acid, if the Ka is big that means acid are strength because the concentrate from RCO2^- dan H⁺ is bigger. If Ka increase, pKa will reduced.