Methanol and Oxygen Reaction (Combustion) | CH₃OH + O₂

Methanol, a highly evaporative toxic chemical and an alcoholic compound, readily burns with oxygen gas and heat is released as a result of combustion. As chemical products, carbon dioxide and water are given if complete combustion is achieved. Otherwise, some amount of carbon monoxide can be given as another product if the supplied oxygen gas amount is not sufficient for a complete combustion.

CH₃OH + O₂ → CO₂ + H₂O

In this tutorial, we will discuss followings.

Balanced reaction of methanol and oxygen Oxidation number change of elements in methanol combustion Thermal energy of the reaction Health, safety and environmental impacts due to combustion of methanol

Methanol

Methanol is the simplest alcoholic compound and an organic compound. methanol contains only one carbon atom, one oxygen atom and four hydrogen atoms. Pure methanol is highly evaporative and vapor can be ignited readily if spark and enough concentration of oxygen gas is found.

Stoichiometric balanced chemical reaction of ethanol and oxygen gases

Two moles of methanol react with three moles of oxygen gas and produce two moles of carbon dioxide and four moles of water.

CH₃OH_(l) + 3O_2(g) → 2CO_2(g) + 4H₂O_(g)

Change of oxidation numbers in ethanol combustion

Because, above mentioned combustion process is a redox reaction, oxidation numbers of some elements are changed as below.

In methanol molecule, only carbon atoms exist at -2 oxidation states and that carbon atom is oxidized to carbon dioxide molecule. In carbon dioxide molecule, carbon is at +4 oxidation state. So, carbon atom is oxidized.
Oxygen is at 0 oxidation state in oxygen molecule (O₂) and that those oxygen atoms are reduced to -2 oxidation state. Therefore, oxygen in oxygen molecule is reduced.

Thermal energy and heat generation

Standard enthalpy of combustion of methanol (ΔH_c⁰_{(CH₃OH,(l))}) = -726.1 kJ mol^-1

Health and safety

Methanol is a highly inflammable liquid and also pure methanol liquid is very evaporative at room temperature. Therefore, methanol vapor can be spread in a large space in a short time period and a small spark is enough to start a fire. So, everyone need to follow safety precautions in using of methanol liquid in any requirement.

Methanol's hazards are as follow.

Inflammable
Acute toxic
Health hazard

Questions

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Methanol and Oxygen Reaction (Combustion) | CH3OH + O2

CH3OH + O2 → CO2 + H2O