Medium Practice — Set 2

Quick Recap — Van't Hoff Factor & Deviations

• Van't Hoff factor $i=\dfrac{\text{observed colligative property}}{\text{calculated (for }i=1)}$; dissociation gives $i>1$, association $i<1$.
• Degree of dissociation: $i=1+\alpha(n-1)$; abnormal molar mass: dissociation $\Rightarrow$ observed $M$ too low, association $\Rightarrow$ too high.
• Deviations from Raoult: positive (A$-$B forces weaker, e.g. ethanol$+$water) or negative (stronger, e.g. acetone$+$chloroform).
• Henry's law: $p=K_H x$; gas solubility falls as temperature rises.