Solution Properties

Saturated A saturated solution is one that has

dissolved in it all the solute that it can normally hold at that temperature

If it has less than the max amount of solute possible, it is unsaturated

Supersaturated

Solution hold more solute than is present in their saturated solutions

Produced by creating saturated solution at high temp and allowing it to gradually cool

Electrolyte

Solutes in aqueous solutions as ions Strong Electrolyte – solute ionized completely (highly

soluble salts or very polar covalent compounds)

NaCl → Na+ + Cl-

Weak Electrolyte – incomplete ionization occurs (poorly soluble salts or weekly polar)

HgCl2 ↔ HgCl+ + Cl-

only a small part of the HgCl2 that is dissolved is present as ions

Non-electrolyte – no ionization occurs (non-polar covalent subtances)

Ionic solutes and some very highly polar molecular solutes are electrolytes

Acids and Bases

They are electrolyte solutions Strong Acid or Base is completely ionized Weak Acids or Bases are not ionized

completely

Concentration of Electrolytes

If each compound below is a strong electrolyte, what is the total concentration of solute particles for each

1) 1.5 M NaCl2) 0.50 M MgCl23) 0.25 M Ca(NO3)2

4) 2.5 M K2S5) A mixture of 10 ml of 0.20 M NaCl and

20 ml of 0.40 M Ca(NO3)2

Vapor Pressure

When solutes are added to a solvent, the solvent molecules no longer evaporate at the same rate but they still condense at the same rate

Solution end up with lower vapor pressures than pure solvent

What Is Happening?

Raoult’s Law

Vapor pressure of a solution lowers at an extent proportional to the concentration

PA = XAPA°

PA – vapor pressure of solution

XA – mole fraction of the solvent

PA° - vapor pressure of pure solvent

Example

Calculate the new vapor pressure of a solution formed by the addition of 100g of sucrose, C12H22O11 , to 1000 g of water, if the vapor pressure of the pure water is 23.8mmHg.

Ideal Solutions

Solvent and solute are alike in size, strength, and type of interactions

When solution isn’t ideal Raoult’s Law is off If interactions between the solute and solvent

molecules is weaker than ideal, the vapor pressure difference will be less than predicted by Raoult’s Law