Energy Conservation & E=M*C2

  • #1
This is question about equation E=m*c2. Why this equation does not required any condition of matter?
Case 1: I take two mole (4 Kg)H2 & one mole(32 Kg)O2 & make water & get energy.
2H2 (4 Kg Hydrogen)+O2 (32 Kg Oxygen)=2H2O(36 Kg of water)+ 572 KJ Energy
Now I convert this water into energy by equation E=m*c2.
Total energy I get is QTotal= (36*c2) + 572 KJ Energy.

»»» Now instead of I convert hydrogen & oxygen into water, I directly convert both gases into energy so total Energy I getting is,
QTotal= m*c2 =(36*c2) Only.
This energy is lesser as compared to first one by amount of “572 KJ Energy”.

Case 2: I have one Kg of boiled water at 100 degree centigrade.
Now I extract 418.7 KJ energy from the water & make it of zero degrees centigrade.
Water at 100 C - 418.7 KJ Energy =Water at 0 C.
Now I convert this zero degree water into energy,
Total energy I getting is,
QTotal=1*c2+418.7 KJ energy

»»» Now I directly convert boiling water into energy,
I getting energy is
QTotal=m*c2=1*c2.
This energy is lesser as compared to first one by amount of “418.7 KJ Energy”.

Why it is occurs? Why energy librated is different for the same initial & final condition of mass?
 

Answers and Replies

  • #2
Dale
Mentor
Insights Author
2020 Award
30,654
7,220
Case 1: I take two mole (4 Kg)H2 & one mole(32 Kg)O2 & make water & get energy.
2H2 (4 Kg Hydrogen)+O2 (32 Kg Oxygen)=2H2O(36 Kg of water)+ 572 KJ Energy
Actually, you will get only 35.9999999999936 kg of water. Everything else then works out fine. This difference in mass between the products and the reactants is called the mass deficit and is closely related to the binding energy. See: http://en.wikipedia.org/wiki/Binding_energy. The mass deficit occurs for all interactions, although as you can see above it is usually pretty small and only noticeable for very strong interactions, like those involving the strong nuclear force.
 
  • #3
Actually, you will get only 35.9999999999936 kg of water. Everything else then works out fine. This difference in mass between the products and the reactants is called the mass deficit and is closely related to the binding energy. See: http://en.wikipedia.org/wiki/Binding_energy. The mass deficit occurs for all interactions, although as you can see above it is usually pretty small and only noticeable for very strong interactions, like those involving the strong nuclear force.
This means that boiling water possesses higher mass then cold water by extremely small amount which is neglected for practical purpose.
OK, Thanks for giving answer.
 

Related Threads on Energy Conservation & E=M*C2

Replies
2
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
14
Views
4K
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
5
Views
4K
  • Last Post
Replies
3
Views
2K
  • Last Post
2
Replies
26
Views
5K
  • Last Post
Replies
11
Views
6K
Top