The third law of thermodynamics states that entropy approaches a minimum as this quantity approaches absolute zero.
In statistical mechanics, this quantity is the conjugate variable to entropy, and for a system at constant volume, it is defined as the derivative of internal energy with respect to entropy. The Van't Hoff equation evaluates the changes in the dissociation constant associated with changes in this quantity, which decreases in throttling processes in real gases due to the (*) Joule-Kelvin effect and which is held constant in Boyle's law. The third law of thermodynamics states that entropy approaches a minimum as this quantity approaches absolute zero. For 10 points, identify this quantity which remains constant in isothermal processes and can be measured in Kelvins or degrees Fahrenheit.
In statistical mechanics, this quantity is the conjugate variable to entropy, and for a system at constant volume, it is defined as the derivative of internal energy with respect to entropy.
{temperature} [prompt on {T}]