Chemistry class 12th Mass_Energy_Equivalence

Mass-Energy Equivalence


1. Einstein's Mass-Energy Equation
The famous equation describing mass-energy equivalence is:


E = mc^2


where:
- E = Energy (in Joules)
- m = Mass (in kilograms)
- c = Speed of light (3.0 x 10^8 m/s)


Since c is extremely large, even a small mass can be converted into a huge amount of energy.


2. Physical Meaning of Mass-Energy Equivalence
- **Mass is a Form of Energy:** Every object with mass has energy even when at rest (Rest Energy:
E0 = mc^2).
- **Energy Has Mass:** Any form of energy (kinetic, thermal) increases the total mass of a system.
- **Mass and Energy Transformation:** Mass can convert into energy (e.g., nuclear reactions), and
energy can convert into mass (e.g., particle collisions).


3. Applications of Mass-Energy Equivalence
(a) **Nuclear Reactions (Fission and Fusion)**
- **Fission:** Uranium nuclei split, releasing energy (used in nuclear reactors).
- **Fusion:** Hydrogen nuclei combine to form helium (powers the Sun).


(b) **Particle Physics**
- High-energy collisions in particle accelerators convert kinetic energy into new particles.


(c) **Matter-Antimatter Annihilation**
- Electron and positron annihilate to produce pure energy (gamma rays).


4. Experimental Proof
- **PET Scans (Medical Imaging):** Detects gamma rays from matter-antimatter annihilation.
- **Nuclear Bombs:** Demonstrates large-scale conversion of mass into energy.
- **Particle Accelerators (CERN):** Confirm mass-energy conversion in experiments.