Colligative Properties, Raoult's Law
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What are colligative properties
Are properties of a solution that change as you add more solute
Amount of solute and freezing points are directly or indirectly related?
indirectly related. As you increase the amount of solute, the freezing point decrease Ex: adding salt to ice
Amount of solute and boiling points are directly or indirectly related?
directly related
Basically, if you add a bunch of solute to a liquid. You are increasing that liquids ability to STAY ____??
A liquid. It decreases freezing point and increases boiling point
How do you calculate the change in freezing or boiling point? (Equation)
delta T = -iKm (freezing) delta T=+iKm (boiling) delta T= change in liqiods temp i= Van’t Hoff factor K=freezing OR boiling point constant (depending on what you are finding) m= solution’s molality (moles of solute/kg solvent)
What is the Van’t Hoff factor?
represented by “i”. is a number that increases as the number of molecules or ions in the solution increases. Ex: NaCl dissolves into TWO ions, i=2 Ex: Ca(NO3)2 dissolves into 3 ions, i=3 Ex: glucose doesn’t dissolve into ions, i=1
Why is “i” negative in the freezing point equation and positive in boiling point equation?
bc when you dissolve a solute in liquid the freezing point goes down (NEGATIVE) and the boiling point goes up (POSITIVE)
Amount of solute and boiling point and Vapor Pressure are directly or indirectly related?
BP & solute= direct BP & VP= indirect solute & VP= indirect
Raoult’s Law of Vapor Pressure depression?
Pa=Xa*Ppure Ppure= vapor pressure of original solvent Xa= % of solvent in new solution Pa= solutions NEW vapor pressure