## Constants

$\ln K = -\frac{\Delta H^{\circ}}{RT} + \frac{\Delta S^{\circ}}{R}$

FrankieClarke2C
Posts: 59
Joined: Fri Sep 28, 2018 12:28 am

### Constants

why we can assume that deltaH and deltaS are constant when using the Van't Hoff equation to calculate K at different temperatures?

Posts: 96
Joined: Fri Sep 28, 2018 12:16 am
Been upvoted: 2 times

### Re: Constants

I think we are just assuming that they are independent of temperature so that we can use those values at two different temperatures in the calculations to solve for K values when temperature changes.

JacobHershenhouse3G
Posts: 32
Joined: Thu Jan 10, 2019 12:17 am

### Re: Constants

When you're solving for k at different temperatures, you're going to be using standard enthalpy and entropy values, so these dont change based on temperature. Thinking back to the first midterm though, we can remember that k does depend on temperature so that's how this concept can be applied to thermochemistry

Roberto Gonzalez 1L
Posts: 39
Joined: Fri Sep 28, 2018 12:17 am

### Re: Constants

As the Van't Hoff Equation is used when the temperature is different for a given reaction, the change in enthalpy and entropy for the reaction remains the same as they are independent of temp and therefore t is the only variable that is different in two situations (where t1 is raised or lowered to t2).