Hello everyone, I'm trying to understand more about how partial pressure works and how to use chemical activity equation. My reference text uses the following example: Note1: A solution is prepared by mixing 2 moles of CHCl3 (chloroform) and 3 moles of (C2H5)2O (diethyl ether). Note2: The vapor pressures of the components at 17 degrees C are pCHCl3 = 34 mmHg and p(C2H5)2O = 196 mmHg. Note3: The vapor pressures of the pure liquids at 17 degrees C are p0CHCl3 = 143 mmHg and p0(C2H5)2O = 397 mmHg. Using this information, shouldn't I be able to find the chemical activity for chloroform and ether? Here are my tools: aB = pB/p0B where aB = Chemical Activity pB = partial pressure of B ? (gas / liquid ?) p0B = vapor pressure of pure liquid B I do not understand if this formula is complete or how to incorporate combining the moles of each substance or how temperature makes a difference. The reference texts just states that "the chemical activity of each substance can be obtained from the following formula" which is the formula I listed above. I also do not understand the distinction between Notes 2 and 3 regarding what the difference is between the vapor pressures of the "components" and of the "pure liquids" ... what does it mean for each? Can anyone assist? Any all help is greatly appreciated!