Colligative Properties, Raoult's Law

Question 1

What are colligative properties

Answer 1

Are properties of a solution that change as you add more solute

Question 2

Amount of solute and freezing points are directly or indirectly related?

Answer 2

indirectly related. As you increase the amount of solute, the freezing point decrease
Ex: adding salt to ice

Question 3

Amount of solute and boiling points are directly or indirectly related?

Answer 3

directly related

Question 4

Basically, if you add a bunch of solute to a liquid. You are increasing that liquids ability to STAY ____??

Answer 4

A liquid.

It decreases freezing point and increases boiling point

Question 5

How do you calculate the change in freezing or boiling point? (Equation)

Answer 5

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)

Question 6

What is the Van’t Hoff factor?

Answer 6

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

Question 7

Why is “i” negative in the freezing point equation and positive in boiling point equation?

Answer 7

bc when you dissolve a solute in liquid the freezing point goes down (NEGATIVE) and the boiling point goes up (POSITIVE)

Question 8

Amount of solute and boiling point and Vapor Pressure are directly or indirectly related?

Answer 8

BP & solute= direct
BP & VP= indirect
solute & VP= indirect

Question 9

Raoult’s Law of Vapor Pressure depression?

Answer 9

Pa=Xa*Ppure

Ppure= vapor pressure of original solvent
Xa= % of solvent in new solution
Pa= solutions NEW vapor pressure