18.1

Outline of section 18.1 Solutions/ solubility

Solution formation

• Homogeneous mixtures
• May be solid liquid or gas
• Factors that affect solubility
  • 1)Stirring
  • 2)Temperature (higher is better)
  • 3)Particle size (smaller is better)

Solubility

• Saturated solution contains the max amount of solute for a given amount of solvent at a constant temperature
  • 36.2 g of sodium chloride in 100 g of water is a saturated solution at 25oC
• Solubility is the amount that dissolves in a set quantity of solvent at a given temp. to produce a saturated solution
• Expressed in g solute per 100 g solvent

Factors affecting solubility of gases  

• Temperature has the opposite effect on gases dissolved in liquids
  • Nitrogen and oxygen come out of solution as the water is heated
• Heat pollution is when industrial plants take cool water from a lake and dump hot water back in causing the temp. of the lake to increase and the amount of O2 dissolved to decrease
• Gas solubility increases as the partial pressure of the gas above the solution increases
  • In soda there is CO2 above the liquid, when opened the CO2 above the liquid escapes causing the CO2 in the liquid to escape.
• Henry’s Law: at a given temp the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid.
  • S1    =    S2
  • P1           P2
• Supersaturated solutions: a solution that contains more solute than is theoretically possible

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