Kc vs Kp vs Kc+/- vs K

[605775499]

Okay so in lecture it was said that Kc is for solid-only, and Kp is for gas-only.
1. What if solids are included?
2. What if a combination of phases are included? ie solute in solvent
3. Some of the practice problems had Kc for a gas-only problem- is any conversion necessary? How would one do that?
4. If K only is given, should I assume Kc, or Kp, or base it off the problem? (I remember my TA saying Kp so I was confused)
5. In the textbook, certain K's are given for certain temperatures. One is labeled as K and the other is Kc +/-. What does that mean?

[Layla Qumsieh 3C]

Pure solids and pure liquids are not included in Kc, nor Kp. You can use the ideal gas law to convert from partial pressure to concentration (PV=nRT, where n/V = concentration). In the textbook, K applies to Kp and Kc is just Kc. Hope this helps

[Daniel Lee 2J]

To answer your third question, Kc can apply to gases and not just aqueous solutions, because they too can have concentrations of moles per liter. Therefore, if your given values are in units such as M, no conversion is necessary. If you really wanted to convert to partial pressures, you could use PV=nRT and solve for P.