Enthalpy of mixing

In <a href="/facts/Thermodynamics/q4hIx3yP">thermodynamics</a>, the enthalpy of mixing (also heat of mixing and excess enthalpy) is the <a href="/facts/Enthalpy/bBou8lCE">enthalpy</a> liberated or absorbed from a <a href="/facts/Chemical_substance/EWcXU41d">substance</a> upon <a href="/facts/Mixing_(process_engineering)/zvhBolV4">mixing</a>. When a substance or <a href="/facts/Chemical_compound/37FXqqtv">compound</a> is combined with any other substance or compound, the enthalpy of mixing is the consequence of the new interactions between the two substances or compounds. This enthalpy, if released <a href="/facts/Exothermic_process/gCuSvpa4">exothermically</a>, can in an extreme case cause an explosion.
Enthalpy of mixing can often be ignored in calculations for mixtures where other <a href="/facts/Heat/FjDGssCs">heat</a> terms exist, or in cases where the <a href="/facts/Ideal_solution/Ho6rPlcs">mixture is ideal</a>. The <a href="/facts/Sign_convention/0yGl2bzD">sign convention</a> is the same as for <a href="/facts/Enthalpy_of_reaction/u5pffxVM">enthalpy of reaction</a>: when the enthalpy of mixing is positive, mixing is <a href="/facts/Endothermic/06xmHw6Q">endothermic</a>, while negative enthalpy of mixing signifies <a href="/facts/Exothermic/gCuSvpa4">exothermic</a> mixing. In ideal mixtures, the enthalpy of mixing is null. In non-ideal mixtures, the <a href="/facts/Thermodynamic_activity/kGUf85XI">thermodynamic activity</a> of each component is different from its concentration by multiplying with the <a href="/facts/Activity_coefficient/ImxE0u7t">activity coefficient</a>.
One approximation for calculating the heat of mixing is <a href="/facts/Flory%25E2%2580%2593Huggins_solution_theory/jAFzcyNy">Flory–Huggins solution theory</a> for polymer solutions.

Enthalpy of mixing open-in-new

Enthalpy of mixing