 # The Law of Conservation of Mass, Formula with Examples

The Law of Conservation of Mass is a fundamental principle in chemistry, which states that mass is neither created nor destroyed in a chemical reaction; it is conserved. This law is often associated with the work of Antoine Lavoisier, a French chemist who made significant contributions to the understanding of chemical reactions and laid the foundation for modern chemistry.

# What is the Law of Conservation of Mass?

The Law of Conservation of Mass is a fundamental principle in chemistry, which states that mass is neither created nor destroyed in a chemical reaction; it is conserved. This law is often associated with the work of Antoine Lavoisier, a French chemist who made significant contributions to the understanding of chemical reactions and laid the foundation for modern chemistry.

## Examples;

### 1. Combustion of Hydrocarbons:

When you burn a piece of wood, which is primarily composed of hydrocarbons (molecules containing carbon and hydrogen), it undergoes combustion in the presence of oxygen to produce carbon dioxide (CO2) and water vapor (H2O).

The chemical equation for the combustion of a generic hydrocarbon (CxHy) can be as follows;

CxHy +O2→CO2+H2O

For methane (CH4) the equation would be as such;

CH4+2O2→CO2+2H2O

For octane a component of gasoline with molecular formula C8H18, the equation shall be;

C8H18+12.5O2→8CO2+9H2O

The Law of Conservation of Mass implies that the total mass of the wood before combustion should be equal to the total mass of the products (carbon dioxide, water vapor, and any ash or residue) after combustion.

### 2. Chemical Reaction: Formation of Water:

The reaction between hydrogen gas (H2) and oxygen gas (O2) to form water (H2O) is a well-known example of the Law of Conservation of Mass. This reaction can be represented as

2H2 + O2 → 2H2O.

According to the law, the total mass of the reactants (hydrogen and oxygen) should be equal to the total mass of the products (water vapor) after the reaction takes place.

### 3. Neutralization Reaction:

Consider the neutralization reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) to produce sodium chloride (NaCl) and water (H2O).

The balanced equation is

HCl + NaOH → NaCl + H2O.

The Law of Conservation of Mass applies here as well, ensuring that the mass of the reactants (HCl and NaOH) is conserved and is equal to the mass of the products (NaCl and H2O).

### 4. Photosynthesis in Plants:

During photosynthesis, plants take in carbon dioxide (CO2) from the atmosphere and water (H2O) from the soil. Through the process of photosynthesis, they convert these molecules into glucose (C6H12O6) and oxygen (O2) using the energy from sunlight.

The chemical equation of photosynthesis

6CO2+6H2O+light energy→ C6H12O6+6O2

According to the Law of Conservation of Mass, the total mass of the carbon dioxide and water molecules taken in by the plant should be equal to the total mass of glucose and oxygen produced during photosynthesis.

### 5. Respiration in Living Organisms:

In cellular respiration, living organisms, including humans, take in oxygen (O2) and glucose (C6H12O6) and convert them into carbon dioxide (CO2), water (H2O), and energy in the form of adenosine triphosphate (ATP).

The chemical equation for cellular respiration is;

C6H12O6+6O2→6CO2+6H2O+energy (ATP)

The law implies that the total mass of oxygen and glucose consumed during respiration must be equal to the total mass of carbon dioxide, water, and the energy produced (in the form of ATP).

## Derivatives of the Law of Conservation of Mass:

1. Law of Conservation of Matter: This is a broader statement that includes not only mass but also the total number of atoms of each element in a chemical reaction. It asserts that the total number of atoms of each element remains constant before and after a chemical reaction.

2. Law of Conservation of Mass-Energy (Mass-Energy Equivalence): This principle, famously described by Albert Einstein’s equation E=mc2, states that mass and energy are interchangeable. In nuclear reactions, a tiny amount of mass can be converted into a significant amount of energy, in accordance with the conservation of mass energy.

3. Law of Conservation of Charge: In addition to mass, electric charge is conserved in chemical and physical processes. This means that the total electric charge of a closed system remains constant.

## Conclusion:

In summary, the Law of Conservation of Mass is a fundamental concept in chemistry that states mass is conserved in chemical reactions. It has several derivatives and is closely related to the Law of Conservation of Matter, the Law of Conservation of mass energy, and the Law of Conservation of Charge, each of which plays a crucial role in understanding various aspects of physical and chemical processes.

## 1 Comment

• September 29, 2023 at 7:51 am
Dillip kumar Pramanik

Very useful and important concept 👌👌