Pentane Structure Pentane Chemical Properties Melting point -130 °C Boiling point 36 °C density 0.626 g/mL at 25 °C(lit.) vapor density 2.48 (vs air) vapor pressure 26.98 psi ( 55 °C) refractive index n20/D 1.358 Fp −57 °F storage temp. 2-8°C solubility ethanol: soluble(lit.) form Liquid color Colorless