Is law of conservation of mass not true for nulcear reactions?

Answer 1

it is not totally true
some mass is converted into energy
but if we add energy also then it is true
Einstein gave a formula e = m*c*c
try this http://www.worsleyschool.net/science/files/emc2/emc2.html

Answer 2

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RE:
Is law of conservation of mass not true for nulcear reactions?

Answer 3

False . all reactions donot follow law of conservation of mass but the difference is negligible and hence neglected. The principle of nuclear reactions is that the loss in mass is converted into energy. Here is Einstein's eqn : E=mc^2. here m is actually the loss in weight when reactants are converted to products.

Answer 4

It holds true. But some mass gets converted by the Einstein equation:
E=mc^2

Answer 5

Nuclear Reactions :
Kinetic energy may be released during the course of a reaction (exothermic reaction) or kinetic energy may have to be supplied for the reaction to take place (endothermic reaction). This can be calculated by reference to a table of very accurate particle rest masses (see http://physics.nist.gov/PhysRefData/Compositions/index.html), as follows. According to the reference tables, the 63Li nucleus has a relative atomic mass of 6.015 atomic mass units (abbreviated u), the deuteron has 2.014 u, and the helium-4 nucleus has 4.0026 u Thus:

Total rest mass on left side = 6.015 + 2.014 = 8.029 u
Total rest mass on right side = 2 × 4.0026 = 8.0052 u
Missing rest mass = 8.029 - 8.0052 = 0.0238 atomic mass units.
In a nuclear reaction, the total (relativistic) energy is conserved. The "missing" rest mass must therefore reappear as kinetic energy released in the reaction; its source is the nuclear binding energy. Using Einstein's mass-energy equivalence formula E = mc², the amount of energy released can be determined. We first need the energy equivalent of one atomic mass unit:

1 u c2 = (1.66054 × 10-27 kg) × (2.99792 × 108 m/s)2
= 1.49242 × 10-10 kg (m/s)2 = 1.49242 × 10-10 J (Joule)
× (1 MeV / 1.60218 × 10-13 J)
= 931.49 MeV,
so 1 u c2 = 931.49 MeV.
Hence, the energy released is 0.0238 × 931 MeV = 22.4 MeV.

Expressed differently: the mass is reduced by 0.3 %, corresponding to 0.3 % of 90 PJ/kg is 300 TJ/kg.

This is a large amount of energy for a nuclear reaction; the amount is so high because the binding energy per nucleon of the helium-4 nucleus is unusually high, because the He-4 nucleus is doubly magic. (The He-4 nucleus is unusually stable and tightly-bound for the same reason that the helium atom is inert: each pair of protons and neutrons in He-4 occupies a filled 1s nuclear orbital in the same way that the pair of electrons in the helium atom occupy a filled 1s electron orbital). Consequently, alpha particles appear frequently on the right hand side of nuclear reactions.

The energy released in a nuclear reaction can appear mainly in one of three ways:

kinetic energy of the product particles
emission of very high energy photons, called gamma rays
some energy may remain in the nucleus, as a metastable energy level.
When the product nucleus is metastable, this is indicated by placing an asterisk ("*") next to its atomic number. This energy is eventually released through nuclear decay.

A small amount of energy may also emerge in the form of X-rays. Generally, the product nucleus has a different atomic number, and thus the configuration of its electron shells is wrong. As the electrons rearrange themselves and drop to lower energy levels, internal transition X-rays (X-rays with precisely defined emission lines) may be emitted.

Answer 6

It is not true .there is en equivalence of mass and energy stated
by E = m*c^2 ( c speed of light,E energy)
so certain mass is transformed into energy

Answer 7

we cant say it is not true for all nuclear reactions.. it is valid for some nuclear reactions also.. in some common chemical reactions also we cant use this law...

Answer 8

yes. the defective mass is converted into energy