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Colligative Properties. Colligative Properties. Properties where how much solute dissolved matters not what is being dissolved. Ex: Osmosis. Colligative Properties. Boiling Point Elevation Ex: coolant/ethylene glycol Lowers the boiling point of water Boiling point elevation ∆T = k b m.
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Colligative Properties • Properties where how much solute dissolved matters not what is being dissolved. • Ex: Osmosis
Colligative Properties • Boiling Point Elevation • Ex: coolant/ethylene glycol • Lowers the boiling point of water • Boiling point elevation • ∆T = kbm
Colligative Properties • Boiling point elevation • ∆T = kbm • What is the boiling point of 50. g of ethylene glycol in 50. g of water?
Colligative Properties • Freezing Point Depression • Ex: salt on ice • This melts ice by lowering the freezing point of the water • Ex: Antifreeze/ethylene glycol • Freezing point depression • ∆T = kfm
Colligative Properties • Freezing point depression • ∆T = kfm • What is the freezing point of 25 g of glucose, C6H12O6, in 75 g of ethanol?
Colligative Properties • This works well for nonelectrolytes • This a problem for electrolytes • Electrolytes (ionic compounds and acids) break into ions in water. • Remember the definition of a colligative property • It doesn’t matter what is dissolved just how much
Colligative Properties • NaCl Na+ + Cl- • 1 m of NaCl is really 1 m of Na+ and 1 m Cl- giving a total of 2 m • K3PO4 3K+ + PO4-3 • .25 m of K3PO4 is really .75 m of K+ and .25 PO4-3 giving a total of 1.0 m
Colligative Properties • For the following solutions what is the total concentration. • 0.15 m CuCl2 • 2.5 m CH3 • 0.50 m H2CO3 • 0.20 m Al2(SiO3)3
Colligative Properties • Which of the following would have the highest boiling point? • 0.25 m KCN • 1.0 m CH3OH • 0.50 m Ca(NO3)2 • 0.40 m HCl
Colligative Properties • What is the boiling point of 5.0 g of CuSO4 in 20. g of water?