# Methanol - Thermophysical Properties

## Chemical, physical and thermal properties of methanol, CH_{3}OH (also called carbinol, wood alcohol, hydroxy methyl and methyl alcohol). Phase diagram included.

**Methanol, CH _{3}-OH, **is a colorless, fairly volatile liquid with a faintly sweet pungent odor, similar, but somewhat milder and sweeter than ethanol.

Methanol is toxic, and may cause blindness. The vapors are slightly heavier than air and may explode if ignited.

Methanol is used to make chemicals, to remove water from automotive and aviation fuels, as a solvent for paints and plastics, and as an ingredient in a wide variety of products.

The phase diagram of methanol is shown below the table.

Chemical, physical and thermal properties of ethanol:

Values are given for liquid at 25^{o}C /77^{o}F / 298 K and 1 bara, if not other phase, temperature or pressure given.

Property | Value | Unit | Value | Unit | Value | Unit | Value | Unit | |||

Acidity (pK_{a1}) | 15.3 | ||||||||||

Autoignition temperature | 737 | K | 464 | °C | 867 | °F | |||||

Boiling Point | 337.85 | K | 64.7 | °C | 148.5 | °F | |||||

Critical density | 8.7852 | mol/dm^{3} | 281 | kg/m^{3} | 0.546 | slug/ft^{3} | 17.6 | lb/ft^{3} | |||

Critical Pressure | 8.22 | MPa=MN/m^{2} | 82.2 | bar | 81.1 | atm | 1192 | psi=lb_{f}/in^{2} | |||

Critical temperature | 513.4 | K | 240.2 | °C | 464.4 | °F | |||||

Critical Volume | 114 | cm^{3}/mol | 0.003552456 | m^{3}/kg | 1.831 | ft^{3}/slug | 0.05690 | ft^{3}/lb | |||

Density (gas) at 0.17 bar | 6.87 | mol/m^{3} | 0.220 | kg/m^{3} | 0.00043 | slug/ft^{3} | 0.0137 | lb/ft^{3} | |||

Density (liquid) | 24540 | mol/m^{3} | 786.3 | kg/m^{3} | 1.526 | slug/ft^{3} | 49.09 | lb/ft^{3} | |||

Flammable, gas and liquid | yes | ||||||||||

Flash point | 284 | K | 11 | °C | 52 | °F | |||||

Gas constant, individual - R | 259.5 | J/kg K | 0.07208 | Wh/(kg K) | 1552 | [ft lb_{f}/slug °R] | 48.23 | [ft lb_{f}/lb °R] | |||

Gibbs free energy of formation (gas) | -163 | kJ/mol | -5087 | kJ/kg | -2187 | Btu/lb | |||||

Heat (enthalpy) of combustion (gas) | 726.1 | kJ/mol | 22661 | kJ/kg | 9.7 | Btu/lb | |||||

Heat (enthalpy) of combustion (liquid) | -727 | kJ/mol | -22689 | kJ/kg | -9.8 | Btu/lb | |||||

Heat (enthalpy) of formation (gas) | -205 | kJ/mol | -6398 | kJ/kg | -2751 | Btu/lb | |||||

Heat (enthalpy) of formation (liquid) | -239 | kJ/mol | -7459 | kJ/kg | -3207 | Btu/lb | |||||

Heat (enthalpy) of fusion at -143°F/-97°C | 3.18 | kJ/mol | 99 | kJ/kg | 42.67 | Btu/lb | |||||

Heat (enthalpy) of evaporation | 37.34 | kJ/mol | 1165 | kJ/kg | 501.01 | Btu/lb | |||||

Heat capacity, Cp (gas) at 0.17 bar | 116 | J/mol K | 3.62 | kJ/kg K | 0.865 | Btu/lb°F or cal/g K | |||||

Heat capacity, Cp (liquid) | 81.2 | J/mol K | 21.95 | kJ/kg K | 5.242 | Btu/lb°F or cal/g K | |||||

Heat capacity, Cp (solid) at -148°F/-100°C | 105 | J/mol K | 28.38 | kJ/kg K | 6.778 | Btu/lb°F or cal/g K | |||||

Heat capacity, Cv (gas) at 0.17 bar | 94.5 | J/mol K | 2.95 | kJ/kg K | 0.704 | Btu/lb°F or cal/g K | |||||

Heat capacity, Cv (liquid) | 67.9 | J/mol K | 2.12 | kJ/kg K | 0.506 | Btu/lb°F or cal/g K | |||||

Ionization potential | 10.84 | eV | |||||||||

log K_{OW} (Octanol/Water Partition Coefficient) | -0.77 | ||||||||||

Melting point | 175.55 | K | -97.6 | °C | -143.7 | °F | |||||

Molecular Weight | 32.042 | g/mol | 0.07064 | lb/mol | |||||||

Solubility in water | 1000 | mg/ml | (Miscible in water) | ||||||||

Sound velocity in gas, at 0.17 bar | 297 | m/s | 974 | ft/s | 665 | mi/h | |||||

Sound velocity in liquid | 1100 | m/s | 3608 | ft/s | 2464 | mi/h | |||||

Specific Gravity (gas) (relativ to air) | 1.11 | ||||||||||

Specific Gravity (liquid) (relativ to water) | 0.79 | ||||||||||

Specific Heat Ratio (gas) - cp/cv | 1.23 | ||||||||||

Specific Heat Ratio (liquid) - cp/cv | 1.20 | ||||||||||

Specific Volume (gas) 0.17 bar | 0.146 | m^{3}/mol | 4.55 | m^{3}/kg | 2342.63 | ft^{3}/slug | 72.81 | ft^{3}/lb | |||

Specific Volume (liquid) | 0.0000408 | m^{3}/mol | 0.00127 | m^{3}/kg | 0.655 | ft^{3}/slug | 0.0204 | ft^{3}/lb | |||

Standard molar entropy, S° (gas) | 240 | J/mol K | 7.49 | kJ/kg K | 1.79 | Btu/lb °F | |||||

Standard molar entropy, S° (liquid) | 127 | J/mol K | 3.96 | kJ/kg K | 0.95 | Btu/lb °F | |||||

Surface tension | 22.07 | dynes/cm | 0.02207 | N/m | |||||||

Thermal Conductivity | 0.202 | W/m°C | 0.116713 | Btu/hr ft °F | |||||||

Triple point pressure | 1.86*10^{-7} | MPa=MN/m^{2} | 1.86*10^{-6} | bar | 1.84*10^{-6} | atm | 2.70*10^{-5} | psi=lbf/in^{2} | |||

Triple point temperature | 175.50 | K | -97.7 | °C | -143.77 | °F | |||||

Vapor (saturation) pressure | 0.0169 | MPa=MN/m^{2} | 127.0 | mm Hg | 0.1671 | atm | 2.46 | psi=lbf/in^{2} | |||

Viscosity, dynamic (absolute) | 0.544 | cP | 365.55 | [lbm /ft s*10^{-6}] | 11.36 | [lbf s/ft^{2} *10^{-6}] | |||||

Viscosity, kinematic | 0.692 | cSt | 7.4 | [ft^{2}/s*10^{-6}] |

Methanol is a *liquid* at standard conditions. However, at low temperature and/or very high pressures it becomes a solid.

The phase diagram for methanol shows the phase behavior with changes in temperature and pressure. The curve between the critical point and the triple point shows the methanol boiling point with changes in pressure. It also shows the saturation pressure with changes in temperature.

At the **critical point** there is no change of state when pressure is increased or if heat is added.

The **triple point** of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.

See also more about atmospheric pressure, and STP - Standard Temperature and Pressure & NTP - Normal Temperature and Pressure, as well as **Thermophysical properties** of:

Acetone, Acetylene, Air, Ammonia, Argon, Butane, Carbon dioxide, Carbon monoxide, Ethane, Ethanol, Helium, Hydrogen, Methane, Nitrogen, Oxygen, Propane, Water and Heavy water, D_{2}O.

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