Why does only Temp affect K?

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DLee_1L
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Why does only Temp affect K?

Postby DLee_1L » Fri Jan 10, 2020 10:21 am

Can anyone explain to me why is temperature the only thing that can affect the equilibrium constant? I can kind of see why for Kp because of the PV/T balancing, but don't understand why temperature affects Kc?

Ivan Tadeja 1G
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Re: Why does only Temp affect K?

Postby Ivan Tadeja 1G » Fri Jan 10, 2020 10:29 am

Kc is dependent on temperature. A change in T would change the value of Kc, and this value will scale with respect to what kind of reaction is occurring (endothermic/exothermic).

Jessica Li 4F
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Re: Why does only Temp affect K?

Postby Jessica Li 4F » Fri Jan 10, 2020 10:30 am

For any given concentrations, the ratio will always be the same, regardless of what the concentrations are, so they don't change the value of K. However, temperature affects K because changes in temperature shift the reaction toward a certain side. Think of temp. as a reactant or product in the reaction. If endothermic, it would look something like this:
Reactants + Temperature -> Products
If you increase the temperature, the reaction will shift toward the products in equilibrium, and hence Kc would be have to be changed.

Tyler Angtuaco 1G
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Re: Why does only Temp affect K?

Postby Tyler Angtuaco 1G » Fri Jan 10, 2020 10:41 am

Just a speculation, but I would assume temperature affects the rate at which a reaction occurs, causing the equilibrium values of products and reactants to be different. This is because the temperature affects the viability of a reaction in the first place and thus the amount of products formed/reactants used.

William Francis 2E
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Re: Why does only Temp affect K?

Postby William Francis 2E » Fri Jan 10, 2020 10:52 am

Temperature affects Kc because the forward reaction is either exothermic or endothermic. If the forward reaction is endothermic, then the Kc value will be larger when the temperature is higher since the forward reaction will absorb the added heat and produce a greater proportion of products to reactants than at a lower temperature. Similarly, the Kc value will decrease as temperature increases if the forward reaction is exothermic and the reverse reaction is endothermic.

lauraxie2e
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Re: Why does only Temp affect K?

Postby lauraxie2e » Sat Jan 11, 2020 12:57 pm

Temperature is combined with the reactants to form the products so when you increase the temperature more reactants are formed changing K

Madelyn Romberg 1H
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Re: Why does only Temp affect K?

Postby Madelyn Romberg 1H » Sat Jan 11, 2020 3:18 pm

Temperature can alter the stability of the molecules in the reaction. Hence, by changing the temperature, the products or reactants may become more/less stable at different temperatures. With this information, the reaction my shift to the left or right, altering our K.

Celine 1F
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Re: Why does only Temp affect K?

Postby Celine 1F » Sat Jan 11, 2020 3:31 pm

If the temperature changes, the reaction shifts to one side in equilibrium, changing K

Kayla Maldonado 1C
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Re: Why does only Temp affect K?

Postby Kayla Maldonado 1C » Sat Jan 11, 2020 3:54 pm

William Francis 2E wrote:Temperature affects Kc because the forward reaction is either exothermic or endothermic. If the forward reaction is endothermic, then the Kc value will be larger when the temperature is higher since the forward reaction will absorb the added heat and produce a greater proportion of products to reactants than at a lower temperature. Similarly, the Kc value will decrease as temperature increases if the forward reaction is exothermic and the reverse reaction is endothermic.


How do we know if the forward reaction is exothermic or endothermic?

Ivan Tadeja 1G
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Re: Why does only Temp affect K?

Postby Ivan Tadeja 1G » Sun Feb 16, 2020 10:00 pm

Kayla Maldonado 1A wrote:
William Francis 2E wrote:Temperature affects Kc because the forward reaction is either exothermic or endothermic. If the forward reaction is endothermic, then the Kc value will be larger when the temperature is higher since the forward reaction will absorb the added heat and produce a greater proportion of products to reactants than at a lower temperature. Similarly, the Kc value will decrease as temperature increases if the forward reaction is exothermic and the reverse reaction is endothermic.


How do we know if the forward reaction is exothermic or endothermic?


I believe that this would be a matter of checking the change in enthalpy (). Positive would be endothermic, negative would be exothermic.

DLee_1L
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Re: Why does only Temp affect K?

Postby DLee_1L » Fri Feb 21, 2020 12:13 am

Yeah, you can't really tell if a reaction is exo or endothermic just by looking at the equilibrium constant. Enthalpy is the best way to see if a reaction is exothermic or endothermic because it is the measurement of how much heat is transferred. If enthalpy is negative, heat is leaving the system thus exothermic. If heat is entering the system, enthalpy is positive, thus endothermic.


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