# Compare the amount of mass converted to energy in nuclear

Chapter 17, Problem 30RQ

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QUESTION:

Compare the amount of mass converted to energy in nuclear reactions and in chemical reactions.

In nuclear reactions, the nuclei of atoms themselves undergo changes. The number of protons and/or neutrons in the nucleus actually changes, meaning that the atom is transmuted into a different element. This result is impossible with chemical reactions, which is why alchemists in the Middle Ages were never able to transmute lead into gold. There are three basic types of nuclear reactions: radioactive decay, fission and fusion. In all three cases, the mass of the products are not equal to the mass of the reactants, something which never happens during chemical reactions. In any nuclear reaction, a very small portion of the matter in the reactant nuclei is transformed into pure energy according to Einstein's famous E=mc equation. This equation means that the amount of energy created is equal to the mass lost multiplied by the speed of light squared--an incredible amount of energy from a small amount of matter. Nuclear reactions are kind of in the middle between the two extremes of chemical reactions and elementary particle reactions. In an atomic nucleus, the binding energy contributes anywhere from 0.1% up to about 1% of the total energy of the nucleus. This is a lot less than with the color force in the proton, but it's still enough that it needs to be counted as a contribution to the mass of the nucleus. So that's why we say that mass is converted to energy in nuclear reactions: the "mass" that is being converted is really just binding energy, but there's enough of this energy that when you look at the nucleus as a particle, you need to factor in the binding energy to get the right mass. That's not the case with chemical reactions; we can just ignore the binding energ

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