SolutionsSolution Solvation Solute + Solvent Solutes: Can be solid, liquid, or gas Solvent: Liquid
Temperature and SolubilityIncreased temperature usually increases thesolubility of a solute in a solvent...But not alwaysExceptions: NaCl and CsCl
Temperature and Solubility of GasesInverserelationshipWhy do Brooktrout like coldwater?
What about pressure and solubility? Has no effect on solubility of solid and liquid solutes Gases are different Henry’s Law: Solubility is directly proportional to pressure SCUBA diving and “the bends”
Solvents: “Like Dissolves Like”Properties of solvents- “Like dissolves like” • Solvents are either polar or non-polar • CH3-CH2-CH2-CH2-CH2-CH3 (Hexane, a non-polar solvent) • H2O (water, a polar solvent) • Hexane will dissolve oils, greases, Styrofoam • Water will dissolve ionic substances like NaCl or polar liquids like alcohol • Hexane and water are immiscible
How do soaps work?Soaps were originally madefrom animal fat and ashesHydrophobic end dissolves oilsHydrophilic end is attracted towaterThe result: clean clothes
Solutions and DilutionsHow do you make 1.0 liter of a 0.1MNaOH solution?NaOH weighs 40.0 grams/moleA 0.1M solution contains 0.1 mole ofsolute per 1.0 liter of solutionTake 4.0 grams of NaOH, put it in a 1.0liter volumetric ﬂask, ﬁll with water tothe line Volumetric Flasks
Dilutions: How do you make a dilute solution from a stock solution?How do you make 50.0 ml of a 0.25M NaOHsolution from a 1.0M solution? Mc x Vc = Md x Vd 1.0M x Vc = 0.25M x 50.0 ml Vc= 12.5 ml of 1.0M NaOH;take this and add it to 37.5 ml of water
Titrations: Using a solution of knownconcentration to ﬁnd the concentration of an unknown solution Usually done to ﬁnd the concentration of an unknown acid or base Neutralization reaction Indicator dye is used to show ‘endpoint’ Performing a titration Ma x Va = Mb x Vb
A Sample Titration... What is the concentration of 25.0 ml of HCl if it takes 75 ml of 0.1M NaOH to reach a ‘pink’ endpoint? Ma x 25.0 ml = 0.1M x 75 mlMa = 0.3M; this is the concentration of the HCl
Freezing Point DepressionWhen solutes dissolve in solvents the freezingpoint of the solvent is lowered The boiling point is elevatedAre there biological applications to this?
Hibernation and Survival in Cold Climates Wood Frog Tfp = (1.86)(#Particles)(Moles solute) Kg Solvent