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In thermodynamics, an exothermic process (from Ancient Greek έξω (éxō) 'outward' and θερμικός (thermikós) 'thermal') [1] is a thermodynamic process or reaction that releases energy from the system to its surroundings, [2] usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a ...
The reduction of iron (III) oxide by aluminium releases sufficient heat to yield molten iron. In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change Δ H ⚬ is negative." [1][2] Exothermic reactions usually release heat. The term is often confused with exergonic reaction, which IUPAC defines as ...
A reaction with a negative Q value is endothermic, i.e. requires a net energy input, since the kinetic energy of the final state is less than the kinetic energy of the initial state. [1] Observe that a chemical reaction is exothermic when it has a negative enthalpy of reaction, in contrast a positive Q value in a nuclear reaction.
Nuclear physics. In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a transformation of at least one nuclide to another. If a nucleus interacts with another nucleus or ...
The Van 't Hoff equation relates the change in the equilibrium constant, Keq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, ΔrH⊖, for the process. The subscript means "reaction" and the superscript means "standard". It was proposed by Dutch chemist Jacobus Henricus van 't Hoff in 1884 in his book ...
The enthalpy of solution is most often expressed in kJ / mol at constant temperature. The energy change can be regarded as being made up of three parts: the endothermic breaking of bonds within the solute and within the solvent, and the formation of attractions between the solute and the solvent. An ideal solution has a null enthalpy of mixing.
A fusion energy gain factor, usually expressed with the symbol Q, is the ratio of fusion power produced in a nuclear fusion reactor to the power required to maintain the plasma in steady state. The condition of Q = 1, when the power being released by the fusion reactions is equal to the required heating power, is referred to as breakeven, or in ...
A thermochemical equation is a balanced stoichiometric chemical equation that represents the energy changes from a system to its surroundings. One such equation involves the enthalpy change, which is denoted with ΔH. In variable form, a thermochemical equation would appear similar to the following: A + B → C. ΔH = (±) #.