The first law states that energy cannot be created or destroyed. The work done during an adiabatic process depends only on the initial and final states of the system, and not on the path taken. The internal energy change for any cyclic process is zero. Compare with zero order reaction and second order reaction . The sum of concentration exponents in the rate law for a first order reaction is one.
Many radioactive decays are first order reactions.
A nuclear reaction in which an atomic nucleus breaks into smaller nuclei of comparable mass, releasing a large amount of energy. Compare with auto-ignition temperature . Ether and acetone have flash points below room temperature, which makes them very dangerous. A fluorescent substance absorbs short wavelength radiation and re-emits it as radiation with a longer wavelength in a very short time. Compare with colloid .