Conservation Of Mass: Definition, Examples And Explanation

The Law of Conservation of Mass is a fundamental principle in chemistry, physics and other natural sciences. Antoine Lavoisier discovered in 1756 that when elements combine or react, the total mass stays the same.

In this blog post, we will see the various definitions and applications of the conservation of mass.

What is the definition of Conservation of Mass?

Conservation of Mass is a fundamental principle in physics that states that the mass of a closed system must remain constant over time.

The Law of Conservation of Mass

To understand the law of conservation of mass, you need to study the principles of chemistry and physics. 

“It states that mass neither can be created nor destroyed, only transformed from one form to another.”

The law has been the same since its origin: Mass doesn’t increase or decrease during chemical reactions, it stays constant.

With the discovery of mass conservation by Antoine Lavoisier, the formulation of mass conservation was laid out. 

Discovery of Mass Conservation By Antoine Lavoisier 

Antoine Lavoisier, renowned for his contributions to modern chemistry, pioneered the concept of mass conservation. 

Through his experiments in the late 1700s, he revealed that the reactants’ mass before and after a chemical change stayed constant. 

This principle was called the ‘Law of Conservation of Mass’. His findings revolutionized chemistry, paving the way for stoichiometry and atomic theory.

Lavoisier found that combustible materials gain weight by taking particles from air, not by losing ‘phlogiston’ as thought before. 

Formulation of Mass Conservation

The Conservation of Mass is fundamental. It can be explained scientifically through Formulation of Mass Conservation. 

Here are the key components and their explanations/symbols:

Formula Description Symbol
Law of Conservation of Mass Mass in an isolated system stays constant. m1 + m2 = m3
Where,m represents the mass of each body
Mass-energy equivalence Energy can only be converted, not created/destroyed. E = mc²
Where,E = Energy of the objectm =  Mass of the objectc = Speed of light i.e, 3 x 108 m/s

Conservation of Mass in Chemical Reactions

To understand conservation of mass in chemical reactions, let me walk you through the Total Mass of the Reactants and Products, as well as Mass Conservation in an Isolated System. 

Knowing and applying these two subsections will give you a better view and understanding of how the law of conservation of mass works in chemistry.

Conservation Of Mass

Total Mass of the Reactants and Products

Chemical reactions follow the Law of Conservation of Mass meaning the total mass of reactants and products never changes. 

Mass of all the reactants (MR) = Mass of all the products (MP)


NaCl + CaO   —>   Na2O + CaCl2

The table below illustrates this concept. 

Mass of reactants 12g 20g 32g
Mass of products 15g 17g 32g

Mass Conservation in an Isolated System

The law of mass conservation is a fundamental principle of isolated systems. This means that the total mass before and after a reaction is always the same. It applies to all kinds of chemical reactions, endothermic and exothermic.

For Example,

Imagine a closed container. If the reactants inside have a mass of 100g, then the products must also have a combined mass of 100g. Mass is never created or destroyed, it’s always converted.

Conservation Of Mass

Though individual atoms may change form, all atoms present in the reactants will show up in the products. 

Like in the combustion of methane and oxygen to form carbon dioxide and water vapor. The total number and type of atoms stay the same- one methane and two oxygen makes one carbon dioxide and two water.

Application of Mass Conservation in Physics

To study the application of mass conservation in physics, you need to understand the definition and principle of conservation of mass. 

For this, let’s focus on the Mass Conservation in an Object’s Rest Mass and Mass Conservation and Energy in Earth’s Atmosphere. 

These two sub-sections briefly explain how the law of conservation of mass applies to an object’s rest mass and the air around the Earth’s atmosphere.

Mass Conservation in an Object’s Rest Mass

The principle of mass conservation is a concept in physics that states the total mass of an isolated system stays the same. 

This includes rest mass, which is the mass of stationary objects. In simpler words, you can’t create or destroy matter in a closed system, but you can convert it from one form to another.

Rest mass is important in areas of physics like relativity and quantum mechanics. 

For instance, in Einstein’s equation,



  • E is energy 
  • m is rest mass
  • c = Speed of light i.e, 3 x 108 m/s

This shows us that energy and matter can be swapped around.

The idea of rest mass conservation has big effects on our understanding of physical matters, like tiny particles and huge celestial bodies like planets and stars. 

Scientists can use this to calculate the amount of energy released in nuclear reactions or fusion processes.

Mass Conservation and Energy in Earth’s Atmosphere

Mass and energy preservation in the earth’s atmosphere is a basic concept of physics. This ensures that matter and energy are conserved throughout various atmospheric processes, including those related to weather. 

  • The balance between incoming and outgoing energy impacts the temperature of the earth’s surface and our lives, such as agriculture and transportation. 
  • Mass and energy conservation also applies to phenomena like cyclones, hurricanes, thunderstorms, and air pollution.
  • This principle plays a major part in natural resource management. This includes air quality maintenance for human health and water treatment plants to remove pollutants from wastewater.
  • 2500 years ago, Greek philosopher Empedocles suggested that matter was made of four elements: Air, Earth, Fire, and Water. His teachings were accepted until further experiments found them wrong.
  • NASA reports from January 2021 say that atmospheric carbon dioxide concentrations are at their highest level in 3 million years. 

Other Applications Of Conservation Of Mass

The Law of Conservation of Mass is essential in various industries, such as 

  • Pharmaceuticals
  • Food production 
  • Environmental science
  • Chemical reactions and optimize production processes while reducing waste. 

View of Mass Conservation in Modern Chemistry

To understand the law of conservation of mass in modern chemistry. These two subsections will help you understand how neither matter nor mass can be created nor destroyed in a chemical reaction. 

Mass Conservation in Chemical Compounds

Chemical compounds obey the principle of mass conservation. This means the total mass stays the same during a reaction. Knowing this helps to understand how much reactants and products are involved.

Law of definite proportions

The law of definite proportions states that compounds always contain elements in fixed proportions by weight. This supports the idea of mass conservation. The ratio of elements is always the same.

Applications of Mass Conservation In Chemistry

  • Modern chemistry uses mass spectrometry and nuclear magnetic resonance to measure chemical compound masses. 
  • This allows us to calculate molecular formulas and explore properties like density, melting points and boiling points.
  • Mass conservation has many useful applications in industries like pharmaceuticals, materials science and biochemistry. 
  • It lets people manipulate atoms and molecules to make new substances or improve existing ones.
  • It’s also an economical solution with social implications. Knowing how much substances go in and out of a reaction helps us use resources efficiently.

Elemental Mass Conservation

Modern chemistry preserves elemental mass via mechanisms that balance chemical equations. 

This is known as stoichiometry and is key to understanding chemical reactions. Balancing reactions ensures accurate measurements during experiments.

Elemental mass conservation is essential for analytical chemistry accuracy and precision. 

Although it’s been established for centuries, it’s still regularly studied to determine how different reactions affect elemental composition. Mass conservation has many uses, from engines to batteries.

Transformation and Property Conservation in Nuclear Reactions

To explain transformation and property conservation in nuclear reactions with total energy and mass conservation in ordinary chemical reactions and closed-system mass conservation as solutions. 

Total Energy and Mass Conservation in Ordinary Chemical Reactions

The law of energy and mass conservation is essential in chemical reactions. Nothing is added or taken away, just broken bonds between atoms. When forming molecules, the mass of reactants equals that of products.

Nuclear Reactions

In nuclear reactions, the laws extend to transformations that alter the nucleus. Forces used release much more energy than your regular chemical reaction. 

Fusion Reactions

Fusion reactions form heavier nuclei, with particles carrying away energy and mass. This energy can be converted into electrical power.

  • It’s important to keep desired properties when altering materials through chemical or nuclear processes, for high-performance fuels or efficient chemical manufacturing.
  • In the 1960s, scientists found elements with radioactive isotopes with longer half-lives than expected. 

Closed System Mass Conservation

Mass Conservation in a Closed System states that the total mass of a closed system remains constant. 

This applies to nuclear reactions, where matter and energy can be converted between one another. 

An example of this is the nuclear fission of uranium which is shown in the table below.

Reactant Mass (kg) Product Mass(kg)
Uranium-235 52 Krypton-92 36
Neutron 1 Barium-141 133
3 More Neutrons
Total 53 Total 169

It’s clear that the mass before and after the reaction remains the same. Matter can’t be created or destroyed during these types of nuclear transformations.

As per Einstein’s Energy-Mass relation equation, matter and energy are interchangeable.

E = mc²

To get the best results from nuclear reactions, it’s ideal to choose isotopes with long half-lives instead of short ones. 

Monitoring the presence of radioactive isotopes in materials throughout their lifecycle is also key.

Importance of Mass Conservation in Science and Everyday Life

To better understand the significance of mass conservation in science and everyday life.

Let’s dive into some sub-sections: quantitative proof of mass conservation, crucial correction of mass conservation in the 1905 theory of relativity, and how mass conservation is always conserved in measurement and combine.

3 2

Quantitative Proof of Mass Conservation

It’s essential to grasp the scientifically-proven ‘Quantitative Proof of Mass Conservation’

Experiment Data

A table can help show this proof. The columns will have data from experiments, verifying that no mass is lost. This evidence helps people understand the concept better.

CH4 (Methane)  +  2O2 (Oxygen)    —>      CO2 (Carbon dioxide)  +   H2O (Water)

Mass of reactants 16g 64g 80g
Mass of products 44g 36g 80g

Mass Conservation’s implications go beyond science. It helps us comprehend natural phenomena and industrial processes.

Scientists show that Earth loses 50k tonnes of mass each year because of space dust. This illustrates Mass Conservation’s importance in our universe. 

Crucial Correction of Mass Conservation in the 1905 Theory of Relativity

The 1905 Theory of Relativity brought about an important change to the conservation of mass. It showed that mass isn’t always conserved, depending on the object’s energy and speed.

The Theory reworked the relationship between energy and mass. It also introduced new ideas like time dilation and length contraction. 

The original law about the conservation of mass was widened to include energy in any system.

Though its implications were huge, the importance of mass conservation is often overlooked outside scientific circles. 

This knowledge has led to advancements in technology like GPS satellites and more efficient nuclear power plants.

It would be a great idea for scientists to keep building on this research to boost technology in various industries. 

Teaching younger generations more about relativity will help create a highly skilled workforce with the right innovative skills to solve global issues. 

Mass Conservation Always Conserved in Measurement and Combine

Mass conservation is a key concept in science and everyday life. It states that total mass in a closed system stays the same despite any physical or chemical changes. 

Mass can’t be created nor destroyed, only transformed or transferred from one form to another. It’s always conserved when measuring or combining substances.

This principle has implications in various fields, such as chemistry, biology, physics, and environmental science. 

  • In chemistry, it’s used to explain chemical reactions where elements change atomic composition, yet keep their mass. 
  • In biology, it’s important for understanding cellular processes, like metabolism and growth. 
  • It forms the basis for Newton’s laws of motion and energy transformations in physics.
  • In environmental science, it helps us study waste management and water treatment plants.
  • Knowing mass conservation is essential for everyday tasks like cooking or mixing chemicals. 
  • It helps ensure ingredients are correctly measured and combined according to specific ratios.

Frequently Asked Questions

How is the principle of Conservation of Mass expressed?

The principle of Conservation of Mass can be expressed as the total mass of the products of a chemical reaction being equal to the total mass of the reactants.

What are some examples of the principle of Conservation of Mass in action?

Any situation where mass is involved can be an example of the principle of Conservation of Mass. 

For example, a solid object moving at a constant velocity demonstrates the principle of Conservation of Mass because the mass of the object remains constant.

What is the reference point for the principle of Conservation of Mass?

The reference point for the principle of Conservation of Mass is the total mass of the system at the beginning of the reaction.

How is the mass of chemical elements and compounds conserved?

The mass of chemical elements and compounds is conserved because the total amount of material present before and after a reaction is the same.

What is the inertial mass of an object?

The inertial mass of an object is a measure of the object’s resistance to changes in its velocity.

What does it mean for a carbon atom to be bound?

When a carbon atom is bound, it means that it is chemically combined with other atoms to form a molecule.

How can we prove that mass is conserved?

Mass is conserved because we can measure the total mass of a system before and after a reaction and show that it remains constant. This can be done using a scale or other measurement device.

Is Momentum Conservation Related to Conservation of Mass?

Momentum conservation in energy is a fundamental principle stating that the total amount of momentum in a closed system remains constant. However, it is important to note that momentum conservation is distinct from the conservation of mass. While energy is conserved in all physical processes, mass can be converted into energy, and vice versa, as demonstrated by Albert Einstein’s famous equation, E = mc². Hence, while the conservation of mass holds true in many scenarios, it is not directly linked to momentum conservation in energy.

Conservation of Mass is related to the formation of nitrates because the total mass of the products of a reaction involving nitrogen and oxygen must be equal to the total mass of the reactants.


Mass conservation always conserves measurement and combination, keeping total mass constant within a closed system. Its invaluable applications across different sciences make it essential for various areas of society since its discovery by Lavoisier. So, even if you can’t conserve your sanity, at least try to conserve mass in your daily life!

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