Change in enthalpy/entropy over temperature

[Kanishkh Patalay]

Why can we assume that the change in entropy and enthalpy is negligible across different temperatures? When using the Van't Hoff equation won't this make our calculation for K at a different temperature value very different than the actual value?

[NicoleN-3F]

Well, the Van't Hoff equation is mostly, for our purposes, a way to relate the change of K in response to changes in temperature. It's showing that K is temperature dependent. The way that K reacts to temperature changes for a specific reaction is linked to the enthalpy of the reaction (whether it's a negative or positive value). We want to assume delta H and delta S are relatively unaffected by these slight changes in temperature because they are measured, in this equation, at standard condition, and because they are delta values, meaning they are inherently differences between other values. Hopefully that made sense.