Is There a Chemical Change When You Burn Wood?

Wood is the plant portion that makes up the majority of a tree’s stem and branches. Wood’s primary purpose is to provide strength and transmit nutrients. This transfer occurs through the xylem and phloem tissues, which are two different types of tissues. Water is transported by xylem, while minerals and other nutrients are transported by phloem.

Natural timbers come in a range of colours, patterns, smells, and other characteristics. It works as a heat and electricity insulator, as well as having acoustic qualities.

The majority of students wonder if burning wood is also considered a chemical reaction. As a result, we shall investigate this subject in depth in this essay.

Is there a chemical shift when wood is burned? Yes, wood combustion is an example of a chemical reaction known as combustion. In the presence of heat and oxygen, wood decomposes into carbon dioxide, water vapour, and ash. The pyrolysis of cellulose material, which forms wood, results in the production of a considerable quantity of heat in this process.

The Burning of Wood’s Chemical Reaction

We know that the majority of wood is made up of cellulose, which is a carbohydrate made up of carbon, hydrogen, and oxygen atoms.

As a result, the finished products are made up of a mixture of these atoms rearranged in various ways.

However, there are two sorts of chemical reactions that might occur when wood is burned.

The initial chemical equation for the change that occurs as a result of incomplete wood combustion is:

CxHyOz (wood)  +   O2   +   Heat    —–>   CaHbOc  (charred wood)    +   CO (gas)   +   Heat 

This equation illustrates the pyrolysis reaction, in which wood is partially burned and then charred.

For the burning of wood, there is another reaction in which the wood is presumed to have totally burned.

The following is the reaction:

CxHyOz   +   O2   +   Heat    ——>    CO2   +   H2O   +   Heat

Both of these reactions, however, are hypothetical because several side products are generated when wood is burned.

Because wood is not a homogeneous material and is accessible in a variety of forms with varying chemical compositions, the products produced by burning wood vary from one sample to the next.

During the process, additional products such as sulphur oxides, ash, and other volatile organic compounds are generated.

What is the definition of a chemical change?

A chemical change, also known as a chemical reaction, is a process in which the atomic arrangement of specific substances, known as reactants, changes as a result of an external force such as temperature, pressure, or another material.

The atomic arrangement of the products created as a result of a chemical reaction is fundamentally different from that of the reactants, and so they have different chemical and physical properties.

You don’t need to go to a chemistry lab to see a chemical reaction. Chemical reactions can be seen all around you if you pay attention to your environment.

A few examples include making cheese, brewing beer, smelting iron, and burning fuels.

Chemical Reactions in Our Everyday Lives

Chemical Change as a Fundamental Concept

In a chemical reaction, certain considerations are taken into account. The following are a handful of them:

• Matter conservation

It cannot be generated or destroyed, but it can be converted from one form to another, according to the Law of Conservation of Matter and Energy.

Because this property holds true for all chemical reactions, chemical equations must always be balanced in terms of atoms.

The chemical reaction for the combustion of methane, for example, is as follows:

CH4   +   2O2    —->   CO2   +   2H2O

Number 2 is placed in front of O2 and H2O as a stoichiometric component in the above reaction to balance the number of hydrogen and oxygen atoms.

The ratio of reactant atoms to product atoms in a chemical reaction equation is referred to as stoichiometry.

• Consideration of Kinetics

To begin any chemical reaction, energy must be supplied. Even when it results in the release of heat, such as when wood is burned, an initial spark is necessary to start the reaction.

The rate of reaction is influenced by a variety of parameters such as catalysts, temperature, reactant concentration, and so on.

• Synthesis of information

Synthesis is a fundamental property of a chemical process, in which one or more products are created from one or more reactants with completely distinct compositions and properties.

• Consideration of energy

A chemical reaction involves the shuffling of atoms, which necessitates the breaking and formation of chemical bonds.

It is well known that energy is consumed when reactant molecules’ bonds are broken, but energy is released when product molecules’ bonds are established.

However, certain processes require more energy and are referred to as endoergic reactions, whilst others produce more heat and are referred to as exoergic reactions.

Endothermic and exothermic reactions are defined as when energy is released in the form of heat.

In most cases, heat evolution favours the production of the product; however, entropy plays a larger role in deciding the reaction’s direction.

The entropy of a system is a measure of how energy is dispersed.

The law of conservation of matter and energy is observed in the chemical change involved in the combustion of wood, where the number of reactant atoms is balanced with the number of product atoms.

As previously stated, the kinetic factors are reliant on the original source of heat, which might be a spark or a burning match stick, for example.

When wood is burned, it produces simpler carbon and hydrogen chemicals such as carbon dioxide, carbon monoxide, and water.

Furthermore, while a source of heat is required at the start of the reaction, burning wood is an exothermic process in which more heat is released.

Because all of the criteria for a chemical reaction are met in the process of burning wood, it is classified as such.

Chemical Changes and Their Types

There are six types of chemical reactions:

• Combination Reaction: Two or more reactants are combined to generate a single product.

A + B   —> AB

• Decomposition Reaction: When one reactant is broken down into two or more products, it is called a decomposition reaction.

A + B   —->   AB (Precipitate)

• Precipitation Reaction: When two solutions mix to generate an insoluble substance, it is known as a precipitation reaction.

A + B   —->   AB (Precipitate)

• Neutralization Reaction: A salt is formed when an acid and an alkali react.

Acid + Base   —>  Salt

• Displacement Reaction: In a compound, atoms of one element are replaced by atoms of another element.

AB + C   –> AC + B

• Combustion Reaction: In the presence of heat, a substance combines with oxygen to produce carbon dioxide, water vapours, and other gaseous products.

It’s an exothermic reaction.

A + O2 + Heat   —>  H2O + CO2

Burning wood is a combustion reaction, as we already know.

Is There a Physical Change When You Burn Wood?

Physical change is a process in which the chemical content of a substance does not change, but molecular rearrangement happens.

It is transient in nature and solely impacts a substance’s physical qualities.

Physical changes usually entail the evolution of energy with the least amount of expenditure. It’s a reversible process, like freezing or boiling water, melting wax, and so on.

Burning wood is not a physical process because it requires a change in the chemical composition of the wood, which results in the production of CO2 and H2O, as well as other by-products, at the end of the reaction.

Furthermore, it is an irreversible process that results in a permanent change in the substance.

As a result, wood burning can be appropriately described as a chemical change.

What is the composition of wood?

Although the composition of wood changes from one species to the next, there are a few constant components; nonetheless, their proportions differ between the two species.

The most important component of wood is cellulose, which is a carbohydrate made up of carbon, hydrogen, and oxygen atoms united.

The proportion of cellulose components varies between 40 and 45 percent.

Hemicelluloses, which are found in the form of Glucomannan, Glucuronoxylan, and other polysaccharides, are also found in wood.

Lignin is the wood’s third most abundant component. Extractives are low molecular weight chemicals found in extracellular areas that are present in the wood.

Hardwood and softwood are the two varieties of wood found in nature. The key variation between them is the amount of lignin in each.

Hardwood lignin is made up of sinapyl alcohol and coniferyl alcohol, whereas softwood lignin is made up of coniferyl alcohol.

Wooden Characteristics

Wood is found in nature in a variety of forms, each with its own set of characteristics, such as colour, odour, texture, and taste.

These characteristics are crucial in the identification of various species. Density and specific gravity, for example, varies from one species to the next.

A few other characteristics are listed below:

• Hygroscopicity: Wood has a proclivity for absorbing moisture from the environment.

Although it absorbs various liquids and gases from the environment, water is the most crucial because any wood piece will always have some moisture due to this feature.

• Swelling and Shrinkage: The moisture content of wood causes it to change its diameter.

Swelling can occur as a result of moisture intake, while shrinkage can occur as a result of moisture removal.

• Strength: It varies a lot amongst different species, which is why they’re used for different things.

• Thermal conductivity: Wood has a low thermal conductivity, which means it doesn’t transport a lot of heat. The thermal conductivity of wood, on the other hand, increases as the moisture content and density of the wood increase.

Wood is an insulator, hence it has electrical qualities. However, if the moisture level is too high, it may be able to transmit some electricity.

• Acoustic Properties: Different noises are produced by wood. It also has the ability to absorb and amplify sound waves.

Wood’s Applications

The following are some of the many uses of wood:

• It is utilised in the construction of dwellings, as well as fencing and landscape ornamentation.

• It’s utilised to make cooking utensils and tools.

• It’s used to make constructions, statues, and carvings, among other things.

• Wood is used to make a variety of musical instruments, including the flute, guitar, and piano.

• It’s used to make cricket bats, hockey sticks, and other sporting equipment.

• It’s also used to make children’s toys.

• Commercially, wood is used to make furniture, ships, fuel, stationery, and other items.


Wood burning is a chemical reaction in which a complex substance is broken down into a simpler substance. It’s a combustion reaction of some sort.

When burning wood, there are two chemical reactions that can occur; the equation for incomplete combustion is as follows:

CXHYOZ + O2 + Heat   —>   CAHBOC + CO + Heat

For complete combustion, use the following formula:

CXHYOZ + O2 + Heat   —>   CO2 + H2O + Heat

Conservation of matter, kinetic considerations, synthesis, and energy considerations are all fundamental ideas in chemical reactions.

Read more: There Are 19 Metals That Aren’t Magnetic

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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