- Joined
- May 2, 2008
- Messages
- 1,454
- Reaction score
- 2
Okay, so we can calculate boiling point elevation using deltaT=kb*m*i, where kb is the constant, m is the molality, and i is the van't hoff factor. Now, suppose we are comparing NaCl with CaO. Theoretically, the van't Hoff factor for both NaCl and CaO will be 2, as both will dissociate into two ions. However, in reality, the CaO will dissociate less than NaCl, as unlike the ions Na+ and Cl-, the ions in CaO will have a 2+ charge (Ca2+, O2-). Thus, Ca2+ and O2- will attract each other more strongly and won't dissociate AS much, and will have a real van't Hoff factor less than 2.
I know on the MCAT we are always supposed to assume ideal conditions. However, what if I'm faced with a question that asks if the boiling point elevation/vapor pressure of a solution is dependent on the charge of the ions AND the molality? Should I ignore the charge factor, since we are supposed to assume ideal conditions? Or is that suggesting to me that the conditions are non-ideal?
I know on the MCAT we are always supposed to assume ideal conditions. However, what if I'm faced with a question that asks if the boiling point elevation/vapor pressure of a solution is dependent on the charge of the ions AND the molality? Should I ignore the charge factor, since we are supposed to assume ideal conditions? Or is that suggesting to me that the conditions are non-ideal?
Last edited: