Law of Conservation of Mass

Law of Conservation of Mass - Examples, FAQs

Edited By Vishal kumar | Updated on Jul 02, 2025 04:31 PM IST

The Law of Conservation of Mass is a core objective in physics and states that in any physical or chemical change, the mass of the system remains constant, attribute mass, virginity or cause, within any closed system, such mass can neither be created nor destroyed. This law is essential in the explanation of various phenomena. From the simplest laboratory chemical processes to the most complex geophysical processes such as the hydrological cycle, this law can be appreciated. For example, a simple cooking exercise, where the combined weight of all ingredients is the same as the weight of the cooked dish and the steam coming off it serves as a demonstration of this principle in practice. These concepts and others like them help to explain the universe in physics and chemistry, which is why these concepts established and upheld mass conservation.

Law of Conservation of Mass - Examples, FAQs

Law of Conservation of Mass

The Law of Conservation of Mass states that "mass can neither be created nor be destroyed in a reaction." The total mass shall always be retained from the start of the reaction till the end.

According to this law, matter cannot be created nor destroyed, also known as the law of indestructibility of matter.

Related Topics

Law of Conservation of Mass Formula

The formula for the law of conservation of mass is given by,

$$
\begin{aligned}
& \frac{\delta \rho}{\delta t}+\nabla \cdot(\rho v)=0 \\
& \rho \text { is density } \\
& \mathrm{t}=\text { time }
\end{aligned}
$$
$\nabla$ = divergence

$v=$ flow velocity

Law of Conservation of Mass Examples

Combustion process: Wood burning is a mass conservation process because it contains oxygen, carbon dioxide, water vapor, and ashes.
Chemical reactions: To make one molecule of H₂O (water) with a molecular weight of 10, hydrogen with a molecular weight of 2 is combined with oxygen with a weight of 8 preserving mass.

NEET Highest Scoring Chapters & Topics

This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.

Download E-book

Also, check-

Frequently Asked Questions (FAQs)

1. Why doesn't mass change during chemical reactions?

Atoms are neither generated nor destroyed during a chemical reaction. To generate products, the atoms of the reactants are simply rearranged. As a result, in a chemical reaction, there is no change in mass.

2. What is the ultimate source of energy if it cannot be created or destroyed?

The Big Bang is the ultimate source of energy in our current cosmos. At the beginning of time, all of the energy was created, and as the cosmos expanded, numerous stages of particulate matter were produced from that energy.By the time of the Modern Universe, energy had been dispersed as mass, kinetic energy, chemical energy in lumps of matter, or radiant energy. Galaxies and stars inside them are used to classify the masses. The sun is one of those stars, and it received its energy from the Big Bang.

3. What is a violation of the law of mass conservation?

Because mass is changed into energy or vice versa, nuclear reactions appear to violate both the Laws of Conservation of Mass and Energy.

4. What is the difference between the mass conservation law and the energy conservation law?

The law of conservation of mass holds that no mass is generated or lost during a chemical process. The mass of a carbon atom does not change as it transitions from a solid to a gas. The law of conservation of energy, on the other hand, maintains that energy cannot be created or destroyed.

5. How does the Law of Conservation of Mass apply to the process of radioactive decay?

In radioactive decay, the total mass-energy is conserved. While some mass is converted to energy, and particles are emitted, the sum of the masses of the decay products plus the energy released equals the mass of the original radioactive nucleus.

6. How does the Law of Conservation of Mass relate to the concept of half-life in radioactive decay?

While half-life describes the rate at which radioactive atoms decay, the Law of Conservation of Mass ensures that the total mass-energy of the system remains constant. The mass lost in decay is converted to energy and particles, preserving the total mass-energy.

7. Can the Law of Conservation of Mass explain why adding salt to water increases its mass?

Yes, when salt dissolves in water, the mass of the solution is equal to the mass of the water plus the mass of the salt. No mass is lost or gained; the salt ions are simply distributed throughout the water, demonstrating mass conservation.

8. How does the Law of Conservation of Mass apply to the process of electrolysis?

In electrolysis, the total mass of the products formed at the electrodes equals the mass of the electrolyte decomposed. While the substances change form, the total mass of the system remains constant, demonstrating mass conservation.

9. How does the Law of Conservation of Mass relate to the concept of dynamic equilibrium in reversible reactions?

In a system at dynamic equilibrium, forward and reverse reactions occur at equal rates. The Law of Conservation of Mass ensures that the total mass of reactants and products remains constant, even as individual molecules continually change form.

10. How does the Law of Conservation of Mass relate to chemical reactions?

In chemical reactions, the Law of Conservation of Mass ensures that the total mass of reactants equals the total mass of products. Atoms are neither created nor destroyed during a reaction; they are only rearranged to form new substances.

11. Can the Law of Conservation of Mass be violated?

In classical physics, the Law of Conservation of Mass cannot be violated. However, in very high-energy situations or at the quantum level, mass and energy can be interconverted according to Einstein's theory of relativity. Even then, the total mass-energy is conserved.

12. What's the relationship between the Law of Conservation of Mass and the Law of Conservation of Energy?

These laws are closely related and can be combined into the Law of Conservation of Mass-Energy. In most chemical reactions, mass and energy are separately conserved. In nuclear reactions, mass can be converted to energy and vice versa, but the total mass-energy is always conserved.

13. What happens to the mass in a nuclear fission reaction?

In nuclear fission, a small amount of mass is converted to a large amount of energy. While it might seem that mass is lost, the total mass-energy is conserved. The "missing" mass has been converted to energy according to E=mc².

14. How does the Law of Conservation of Mass relate to the carbon cycle?

The carbon cycle demonstrates mass conservation on a global scale. Carbon moves between the atmosphere, biosphere, hydrosphere, and geosphere, changing forms but never being created or destroyed. The total amount of carbon on Earth remains constant.

15. How does the Law of Conservation of Mass apply to cooking?

When cooking, ingredients may change form, but their total mass remains the same. For example, when boiling water, the mass of water vapor produced plus the remaining liquid water equals the initial mass of water, assuming no water escapes the system.

16. How does the Law of Conservation of Mass apply to photosynthesis?

In photosynthesis, plants convert carbon dioxide and water into glucose and oxygen using sunlight energy. The total mass of reactants (CO₂ + H₂O) equals the total mass of products (C₆H₁₂O₆ + O₂), demonstrating mass conservation.

17. How does the Law of Conservation of Mass apply to the process of digestion?

During digestion, food is broken down into simpler molecules, but the total mass is conserved. The mass of food consumed equals the mass absorbed by the body plus the mass excreted as waste, assuming no mass is lost through respiration or perspiration.

18. How does the Law of Conservation of Mass apply to the process of rusting?

When iron rusts, it gains mass because it combines with oxygen from the air to form iron oxide. This demonstrates mass conservation: the mass of the rust is equal to the original mass of iron plus the mass of oxygen it has combined with.

19. How does the Law of Conservation of Mass apply to the process of dissolving?

When a substance dissolves, the total mass of the solution equals the mass of the solvent plus the mass of the solute. No mass is lost or gained in the process; it's merely distributed throughout the solution.

20. What is the Law of Conservation of Mass?

The Law of Conservation of Mass states that in a closed system, the total mass of matter remains constant over time, regardless of the processes acting inside the system. This means that mass cannot be created or destroyed, only transformed from one form to another.

21. Can mass be converted to energy?

Yes, according to Einstein's famous equation E=mc², mass can be converted to energy and vice versa. However, in most chemical reactions and everyday processes, the amount of mass converted to energy is negligible and not measurable with conventional instruments.

22. How does the Law of Conservation of Mass apply in nuclear reactions?

In nuclear reactions, a small amount of mass is converted to energy. While this seems to violate the Law of Conservation of Mass, it actually follows Einstein's mass-energy equivalence principle. The total mass-energy of the system remains constant.

23. Why does a candle appear to lose mass when it burns?

When a candle burns, it may seem to lose mass, but this is because the products of combustion (mainly carbon dioxide and water vapor) escape into the air. If you were to collect all these gases, the total mass would equal the original mass of the candle plus the oxygen consumed in burning.

24. How does the Law of Conservation of Mass relate to the water cycle?

The water cycle demonstrates the Law of Conservation of Mass on a global scale. Water changes form (liquid, gas, solid) and moves between the atmosphere, land, and oceans, but the total amount of water on Earth remains constant over time.

25. How does the Law of Conservation of Mass relate to recycling?

Recycling is a practical application of the Law of Conservation of Mass. When materials are recycled, their mass is conserved, but they are transformed into new products. This process helps conserve resources and reduce waste.

26. Can the Law of Conservation of Mass explain why the oceans don't overflow despite constant input from rivers?

Yes, the Law of Conservation of Mass helps explain this. Water entering the oceans from rivers is balanced by water leaving through evaporation. The water cycle continuously redistributes water, but the total amount remains constant.

27. What implications does the Law of Conservation of Mass have for space travel and life support systems?

The Law of Conservation of Mass is crucial for designing life support systems in space. It helps engineers calculate the exact amounts of air, water, and food needed for a mission, and plan for recycling and waste management in closed systems.

28. How does the Law of Conservation of Mass apply to the process of distillation?

In distillation, the total mass of the distillate and the residue equals the mass of the original mixture. While components are separated based on their boiling points, no mass is created or destroyed during the process.

29. Can the Law of Conservation of Mass help explain why the Earth's crust appears to change over geological time?

Yes, the Law of Conservation of Mass applies to geological processes. While the Earth's crust changes through processes like weathering, erosion, and plate tectonics, the total mass of the Earth remains constant. Matter is redistributed but not created or destroyed.

30. How does the Law of Conservation of Mass apply to the process of nuclear fusion in stars?

In nuclear fusion, like in the sun, hydrogen nuclei combine to form helium. While a small amount of mass is converted to energy (making stars shine), the total mass-energy is conserved. This process demonstrates the interchangeability of mass and energy in extreme conditions.

31. What's the difference between mass and weight in the context of conservation?

Mass is conserved, but weight can change. Mass is the amount of matter in an object, while weight is the force of gravity on that mass. An astronaut's mass remains constant in space, but their weight changes due to different gravitational fields.

32. Can living organisms violate the Law of Conservation of Mass?

No, living organisms cannot violate this law. When organisms grow, they gain mass by taking in matter from their environment (food, water, air). When they lose mass, it's released back into the environment through waste, respiration, or decomposition.

33. What role does the Law of Conservation of Mass play in balancing chemical equations?

The Law of Conservation of Mass is the fundamental principle behind balancing chemical equations. When balancing equations, we ensure that the number of atoms of each element is the same on both sides, reflecting that mass is neither created nor destroyed.

34. Can the Law of Conservation of Mass explain why the Earth's mass remains constant?

Yes, the Earth's mass remains relatively constant due to the Law of Conservation of Mass. While meteors add mass and some atmospheric gases escape, these changes are minimal. The Earth's processes mostly involve cycling of matter rather than gain or loss.

35. How does the Law of Conservation of Mass relate to the concept of closed systems?

The Law of Conservation of Mass applies strictly to closed systems where no matter enters or leaves. In practice, many systems we consider are approximately closed, allowing us to apply this law with reasonable accuracy.

36. Can the Law of Conservation of Mass explain why perpetual motion machines are impossible?

While the Law of Conservation of Mass doesn't directly address perpetual motion, it's part of the broader principle of conservation of mass-energy. Perpetual motion machines are impossible because they would violate these conservation laws, creating energy or matter from nothing.

37. Can the Law of Conservation of Mass explain why matter can't be created or destroyed in everyday chemical reactions?

Yes, the Law of Conservation of Mass is the fundamental principle that explains why matter can't be created or destroyed in chemical reactions. Atoms are rearranged, but their total number remains constant, preserving the overall mass.

38. How does the Law of Conservation of Mass apply to the process of sublimation?

During sublimation, a solid changes directly into a gas without passing through the liquid phase. The mass of the gas produced is equal to the mass of the solid that sublimated, demonstrating conservation of mass.

39. What role does the Law of Conservation of Mass play in understanding the composition of the universe?

The Law of Conservation of Mass helps astronomers understand the composition and evolution of the universe. It allows them to track the movement and transformation of matter across cosmic scales, from star formation to galactic collisions.

40. How does the Law of Conservation of Mass relate to the concept of stoichiometry in chemistry?

Stoichiometry, which deals with the quantitative relationships between reactants and products in chemical reactions, is based on the Law of Conservation of Mass. It allows chemists to calculate the amounts of reactants needed or products formed in a reaction.

41. What implications does the Law of Conservation of Mass have for waste management and environmental science?

The Law of Conservation of Mass reminds us that waste doesn't disappear when we throw it away. It emphasizes the need for proper waste management and recycling to prevent pollution and conserve resources, as matter can only be transformed, not destroyed.

42. How does the Law of Conservation of Mass apply to the process of combustion?

In combustion, the total mass of the reactants (fuel + oxygen) equals the total mass of the products (carbon dioxide, water vapor, and other gases). While it may seem that mass is lost as the fuel burns, all the mass is accounted for in the gaseous products.

43. Can the Law of Conservation of Mass help explain why the atmosphere doesn't run out of oxygen?

Yes, the Law of Conservation of Mass helps explain this. Oxygen is constantly cycled through processes like photosynthesis (which produces oxygen) and respiration (which consumes it). The total amount of oxygen remains relatively constant due to these balanced processes.

44. What role does the Law of Conservation of Mass play in understanding climate change?

The Law of Conservation of Mass is crucial in understanding climate change. It helps scientists track the movement of greenhouse gases like carbon dioxide between the atmosphere, oceans, and biosphere, explaining how human activities can disrupt these natural cycles.

45. How does the Law of Conservation of Mass apply to the process of fermentation?

In fermentation, the total mass of the reactants (e.g., glucose) equals the total mass of the products (e.g., ethanol and carbon dioxide). While some products may escape as gases, if collected, their mass plus the remaining solution would equal the initial mass.

46. How does the Law of Conservation of Mass relate to the concept of limiting reagents in chemical reactions?

The concept of limiting reagents is based on the Law of Conservation of Mass. The reagent that's completely consumed determines the amount of product formed, ensuring that mass is conserved and no excess atoms are created or destroyed.

47. Can the Law of Conservation of Mass help explain the formation of sedimentary rocks?

Yes, the Law of Conservation of Mass applies to the formation of sedimentary rocks. The mass of sediments that form the rock equals the mass of eroded material from the source rocks, minus any dissolved minerals carried away by water.

48. What role does the Law of Conservation of Mass play in understanding the nitrogen cycle?

The Law of Conservation of Mass is fundamental to the nitrogen cycle. It ensures that the total amount of nitrogen in the biosphere remains constant as it cycles through various forms (atmospheric N₂, ammonia, nitrates) and between organisms and the environment.

49. Can the Law of Conservation of Mass explain why the mass of a plant increases as it grows?

Yes, the increase in a plant's mass as it grows demonstrates the Law of Conservation of Mass. The plant gains mass by incorporating matter from its environment: carbon dioxide from the air, water and minerals from the soil, all converted into plant biomass through photosynthesis.

50. How does the Law of Conservation of Mass relate to the concept of yield in chemical reactions?

The concept of yield in chemical reactions is based on the Law of Conservation of Mass. The actual yield of a product can be compared to the theoretical yield (calculated assuming complete conversion of limiting reagent) to determine the reaction's efficiency.

51. What implications does the Law of Conservation of Mass have for the field of forensic science?

In forensic science, the Law of Conservation of Mass is crucial for analyzing crime scenes and evidence. It ensures that all matter at a crime scene is accounted for, helping investigators trace the origins and transformations of physical evidence.

52. How does the Law of Conservation of Mass apply to the process of cellular respiration?

In cellular respiration, the total mass of reactants (glucose and oxygen) equals the total mass of products (carbon dioxide and water). While energy is released, no mass is lost; it's simply rearranged into different molecules.

53. How does the Law of Conservation of Mass relate to the concept of mass spectrometry?

Mass spectrometry relies on the Law of Conservation of Mass. It measures the mass-to-charge ratio of ions, allowing scientists to determine the composition of a sample. The total mass of all fragments equals the mass of the original molecule.

54. What role does the Law of Conservation of Mass play in understanding the formation of stars and planets?

The Law of Conservation of Mass is crucial in astrophysics. It explains how matter in nebulae coalesces to form stars and planets. While some mass may be converted to energy in stellar processes, the total mass-energy of the system is conserved.