Table 11.2
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Table 11.2
Why are thevalues of K and Kc different for some of the reactions in table 11.2? Shouldnt they all be the same?
Re: Table 11.2
K is Kp, the equilibrium constant based on the partial pressures. The relationship between Kc and Kp is Kp = Kc(RT)^delta(n). This can be derived from the ideal gas equation (PV=nRT) by letting P = nRT/V (and n/V is the concentration, so this is P = [gas]RT) and plugging that in to the Kp equation (the products/reactants one) and simplifying.
Anyways, we see that since R and T are the same (R is a constant and the K given is for a particular temperature) it just depends on delta(n), which is the change in moles between the products and reactants. For the first couple rows on the table, this is just 0 since there are equal moles of products and reactants. And anything raised to the 0 power is just 1, and anything multiplied by 1 doesn't change and thus Kc = Kp. But further down the table, like F2(g) <=> 2F(g) the difference in moles is 1 (2 moles F minus 1 mol F2 = 1)... so that makes Kp and Kc different by a factor of RT.
The same logic follows for the other different values :) just count the difference in moles to know if Kc and Kp are same or different.
Anyways, we see that since R and T are the same (R is a constant and the K given is for a particular temperature) it just depends on delta(n), which is the change in moles between the products and reactants. For the first couple rows on the table, this is just 0 since there are equal moles of products and reactants. And anything raised to the 0 power is just 1, and anything multiplied by 1 doesn't change and thus Kc = Kp. But further down the table, like F2(g) <=> 2F(g) the difference in moles is 1 (2 moles F minus 1 mol F2 = 1)... so that makes Kp and Kc different by a factor of RT.
The same logic follows for the other different values :) just count the difference in moles to know if Kc and Kp are same or different.
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Re: Table 11.2
To add on, K = Kp is for gases and it is denoted by the units atm (bar, torr, Pa etc.). Kc is for concentration which is denoted by molarity units.
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Re: Table 11.2
Hello,
There are many K’s even ones for dissolving called Ksp which is for dissolving. Also It is different than Kc also Kp is different as there is a calculation to convert Kc to Kp so they can be different.
Hope this helps
There are many K’s even ones for dissolving called Ksp which is for dissolving. Also It is different than Kc also Kp is different as there is a calculation to convert Kc to Kp so they can be different.
Hope this helps
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