Concentration vs Partial Pressure

[owenbella1]

Is there a difference between Concentration and Partial Pressure? In the textbook, they are referred to differently, but I am failing to understand the difference (if there is one) espically with respect to the ICE table problems.

[Iris S]

Yes, there is a difference. Concentration and partial pressure are related by the equation PV = nRT, with P being the pressure, V the volume, n the number of moles of the gas, R the gas constant, and T the temperature. Concentration is n/V, so the partial pressure is equal to the concentration times RT. As for ICE table problems, I think the only time you would need to use this is when converting a given concentration of a gas into a partial pressure in order to calculate the equilibrium constant.

[Audrey Wong 2G]

There is a difference between concentration and partial pressure when it comes to calculating the equilibrium constant. You can use PV=nRT to relate the two values, and the Kc and Kp values are usually not equal to each other, unless the moles of gas in the reactants are equal to the moles of gas in the products. In that case, Kp would equal to Kc.

[Yanaa_Mehra_1K]

Partial pressure and concentration is not the same. While you can have concentrations for gases, you cannot have partial pressures for aqueous solutions. We can use either of them in the ICE table depending on the information given in the question and what it is asking. If concentration is to be calculated, they will give us the value of Kc but if partial pressure is to be used, they will give us the K/Kp value. In case Kp is given but we have the concentration of a gas, we can convert it to partial pressure and vice versa using the equation PV=nRT.
Hope this helps.

[Sandhya_Seetharaman_2A]

The main difference is just that Kc uses the concentrations of the gas and Kp uses the partial pressures for the gas when doing the calculations. I think it just depends on the contextual information given in the problem and/or what it asks you to solve for (like how in Achieve sometimes the units next to the answer blank are different than what’s given in the problem). And either way you can convert between them using PV=nRT as people have mentioned.

[BeauBrown]

They are different like previously stated but when it comes to K, it is still products over reactants.

[Sarah Wang 2G]

Both are calculated by putting products over reactants (Kc is dividing concentration of products by concentration of reactants and Kp is dividing partial pressures of products over partial pressures of reactants) and they both serve the same overall purpose. The main difference is that Kp is only used for gases, while Kc is used for both aqueous solutions and gases. Kp requires you to find or have the partial pressure of each component (may use PV=nRT); Kc requires you to find the concentrations of each component.