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Butane

From Biocrawler, the free encyclopedia.

General
Chemical Name	Butane n-butane
Chemical formula	C H₃(C H₂)₂C H₃
Molecular weight	58.1 g/mol
CAS number	106-97-8
MSDS	Butane MSDS
Physical properties
pH (10% solution with water)	7.0
Phase behavior
Melting point	-138.3 °C (134.9 K)
Boiling point	-0.5 °C (272.7 K)
Heat of vaporization (Δ_vapH)	21 kJ/mol
Safety
Flash point	-60 °C
Precautions
Hazards: Extremely flammable Personal protection: ? Reacts with: ? Storage: Keep container in a well ventilated place
Gas properties
Δ_fH⁰_gas	-126 kJ/mol
S⁰_gas	310 J/mol·K
C_p	97 J/mol·K

General
Chemical Name	2-methylpropane Isobutane
Chemical formula	C H₃C H(C H₃)₂
Molecular weight	58.1 g/mol
Phase behavior
Melting point	-159.6 °C (113.6 K)
Boiling point	-11.7 °C (261.5 K)
Except where noted, all data was produced under conditions of standard temperature and pressure.

Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH₃CH₂CH₂CH₃. Butane is also used as a collective term for n-butane together with its only other isomer, iso-butane (also called i-butane, isobutane, or 2-methylpropane), CH₃CH(CH₃)₂.

Butanes are highly flammable, colorless, easily liquefied gases.

Contents

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Chemical structure

n-Butane has the following chemical structure:

    H   H   H   H
    |   |   |   |
H - C - C - C - C - H
    |   |   |   |
    H   H   H   H

Isobutane, on the other hand, has a branched-chain structure:

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Reactions and uses

When air is plentiful, butane burns to form carbon dioxide and steam:

butane + oxygen -> carbon dioxide + steam

When air is limited, carbon (soot) or carbon monoxide may also be formed.

Butane gas is sold bottled as a fuel for cooking and camping, in which case it is referred to commercially as LPG, or, in the UK, calor gas. It is also used as a petrol component, as a feedstock for the production of base petrochemicals in steam cracking, as fuel for cigarette lighters and as a propellant in aerosol sprays.

Recent concerns with depletion of the ozone layer by freon gases have led to increased use of isobutane as a gas for refrigeration systems, especially in domestic refrigerators and freezers. When used as a refrigerant, isobutane is also known as R600a.

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