[Nuclear Physics]
What is the law of conservation of matter?
The law of conservation of matter is a general law in physics and chemistry applicable for any system closed to all transfers of matter and energy. According to this law, the mass of an object or collection of objects never changes over time, no matter how the constituent parts rearrange themselves. In other words, the mass can neither be created nor destroyed.
Key Facts
- The concept of mass conservation is widely used in many fields such as physics, chemistry, mechanics, and fluid dynamics.
- In chemistry, the calculation of the amount of reactant and products in a chemical reaction, or stoichiometry, is founded on the principle of conservation of mass.
- In fluid dynamics, this law is represented by the continuity equation, which states that all mass flow rates into a control volume are equal to all mass flow rates out of the control volume plus the rate of change of mass within the control volume.
- In the special theory of relativity, certain types of matter may be created or destroyed. Still, the mass and energy associated with such matter remain unchanged in quantity in all of these processes.
Why is the law of conservation of matter so important?
The formulation of this law was crucial in progress from alchemy to the modern natural science of chemistry. Conservation laws are fundamental to our understanding of the physical world in that they describe which processes can or cannot occur in nature.
Can matter be destroyed?
According to classical physics, matter cannot be destructed. But in the special theory of relativity, certain types of matter may be created or destroyed. Still, the mass and energy associated with such matter remain unchanged in quantity in all of these processes. It was found the rest mass of an atomic nucleus is measurably smaller than the sum of the rest masses of its constituent protons, neutrons, and electrons. For example, one of the best-known processes is electron-positron annihilation. Electron–positron annihilation occurs when a negatively charged electron and a positively charged positron collide.
Can matter be created?
According to classical physics, matter cannot be created. But in the special theory of relativity, certain types of matter may be created or destroyed. Still, the mass and energy associated with such matter remain unchanged in quantity in all of these processes. It was found the rest mass of an atomic nucleus is measurably smaller than the sum of the rest masses of its constituent protons, neutrons, and electrons. For example, the pair production phenomenon is associated with the creation and destruction of matter in one reaction.