## what does it do?

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

connie 2C
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### what does it do?

what is the difference between this equation and the other equations we know? what does it relate?

Samuel G Rivera - Discussion 4I
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### Re: what does it do?

The Van't Hoff equation helps us find how K (the equilibrium constant) changes when temperature changes.

(P.S. I was confused about what equation you were referring to in your post. Even though it was in the Van't Hoff equation section, I recommend being specific in the posts just to avoid confusion)

Chris Tai 1B
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Joined: Sat Aug 24, 2019 12:16 am

### Re: what does it do?

When using the Van't Hoff equation, we assume that the difference in enthalpy is considered to be the same, and we assume that the difference in entropy between reactants and products is also the same at these two different temperatures. The reason this is valuable is because it enables us to show the dependence of temperature on the equilibrium constant, K; it's an indirect way to measure enthalpy as well. If the deltaH is known, Van't Hoff can be used to calculate K at a different temperature.

Alison Trinh 1E
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### Re: what does it do?

It helps us calculate the K at different temperatures (if we know the standard DeltaH)

Noe BM 1J
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Joined: Sat Sep 07, 2019 12:17 am

### Re: what does it do?

Could you elaborate a little more on how it's an indirect way to measure enthalpy, please?

Chris Tai 1B wrote:When using the Van't Hoff equation, we assume that the difference in enthalpy is considered to be the same, and we assume that the difference in entropy between reactants and products is also the same at these two different temperatures. The reason this is valuable is because it enables us to show the dependence of temperature on the equilibrium constant, K; it's an indirect way to measure enthalpy as well. If the deltaH is known, Van't Hoff can be used to calculate K at a different temperature.

Trent Yamamoto 2J
Posts: 111
Joined: Sat Aug 17, 2019 12:18 am

### Re: what does it do?

The Van't Hoff Equation helps relate K to the different values of T, since T affects K.

Chris Tai 1B
Posts: 102
Joined: Sat Aug 24, 2019 12:16 am

### Re: what does it do?

Noe BM 1J wrote:Could you elaborate a little more on how it's an indirect way to measure enthalpy, please?

Chris Tai 1B wrote:When using the Van't Hoff equation, we assume that the difference in enthalpy is considered to be the same, and we assume that the difference in entropy between reactants and products is also the same at these two different temperatures. The reason this is valuable is because it enables us to show the dependence of temperature on the equilibrium constant, K; it's an indirect way to measure enthalpy as well. If the deltaH is known, Van't Hoff can be used to calculate K at a different temperature.

The reason we can use the VH equation to indirectly measure enthalpy is because of the presence of enthalpy in the equation itself. The equation is as follows:
ln(K2/K1) = deltaH/R * (1/T1 - 1/T2). If we know two different equilibrium constants at two different temperatures, then we're able to calculate the enthalpy in a more indirect manner (as opposed to the typical method of calculating enthalpy by subtracting enthalpies of formation of the reactants from the products, or doing the same with bond enthalpies etc.)

Mitchell Koss 4G
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### Re: what does it do?

The equ can also be used/written in several forms

Noe BM 1J
Posts: 50
Joined: Sat Sep 07, 2019 12:17 am

### Re: what does it do?

Thank you! I see how it is related and it's definitely useful.

Chris Tai 1B wrote:
Noe BM 1J wrote:Could you elaborate a little more on how it's an indirect way to measure enthalpy, please?

Chris Tai 1B wrote:When using the Van't Hoff equation, we assume that the difference in enthalpy is considered to be the same, and we assume that the difference in entropy between reactants and products is also the same at these two different temperatures. The reason this is valuable is because it enables us to show the dependence of temperature on the equilibrium constant, K; it's an indirect way to measure enthalpy as well. If the deltaH is known, Van't Hoff can be used to calculate K at a different temperature.

The reason we can use the VH equation to indirectly measure enthalpy is because of the presence of enthalpy in the equation itself. The equation is as follows:
ln(K2/K1) = deltaH/R * (1/T1 - 1/T2). If we know two different equilibrium constants at two different temperatures, then we're able to calculate the enthalpy in a more indirect manner (as opposed to the typical method of calculating enthalpy by subtracting enthalpies of formation of the reactants from the products, or doing the same with bond enthalpies etc.)

Veronica Lu 2H
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### Re: what does it do?

it helps you find the K when there are changes in temperature

Jacob Villar 2C
Posts: 105
Joined: Sat Aug 17, 2019 12:18 am

### Re: what does it do?

The Van’t Hoff equation can be used to calculate K when the reaction undergoes temperature changes.

Rosa Munoz 2E
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Joined: Wed Sep 18, 2019 12:21 am

### Re: what does it do?

Allows you to find K at different tempratures

Philip
Posts: 100
Joined: Sat Sep 07, 2019 12:16 am

### Re: what does it do?

Van't Hoff Equation is used to calculate the new equilibrium constant based on temperature change

Ayushi2011
Posts: 101
Joined: Wed Feb 27, 2019 12:17 am

### Re: what does it do?

It relates equilibrium constant to temperature.