Calculating Freezing point

[mshopeful]

---

Members don't see this ad.

In Kaplan the equation to calculate boiling point or freezing point is:
delta T = K*m

But in Destroyer #19 the equation he uses is delta T = K*m*i where i is the number of particles that can dissociate.

Why the difference? Is it because in Destroyer we're calculating freezing point for ions?

 

[jigabodo]

In Kaplan the equation to calculate boiling point or freezing point is:
delta T = K*m

But in Destroyer #19 the equation he uses is delta T = K*m*i where i is the number of particles that can dissociate.

Why the difference? Is it because in Destroyer we're calculating freezing point for ions?

In short, Destroyer's equation is always correct. Kaplan has a nasty habit of leaving out the i, aka "van hoff's" factor. They also forgot to put it in for the osmotic pressure equation, where its supposed to be pi = i m r t.

These threads should help.
http://forums.studentdoctor.net/showthread.php?t=417239&highlight=van+hoff
http://forums.studentdoctor.net/showthread.php?t=418825&highlight=van+hoff
http://forums.studentdoctor.net/showthread.php?t=407068&highlight=van+hoff - scroll down for bob faraples explanation on van hoff's factor.

Hope this helps.