Water

Ice

• Liquid water’s density is greatest 4oC.

• Ice has a 10% greater volume; therefore, lower density.

Ice

Why does ice behave so differently?

• As kinetic energy (speed of the molecules) decreases, hydrogen bonds hold water molecules in place.

• The water molecules are held in an open framework creating a hexagonal symmetry of molecules. This increases the volume.

Aqueous Solutions

• Water samples that contain dissolved substances.

• Solvent - dissolving medium• Solute - dissolved particles• Example - salt water - NaCl is the solute and

the water is the solvent• Characteristics:

– Homogeneous– Stable– They do not settle out– Both solvent and solute will pass through a filter

Describe the process of solvation.

• Watch the next 2 video clips and then answer the above question.

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Other solution questions:

• What substances don’t dissolve in water? Why?

• Why does grease dissolve in gasoline and not water?

• How does soap work?

• How is the relationship summed up?

Electrolytes

• Compounds that conduct an electric current in aqueous solution or molten state.

• All ionic compounds are electrolytes

nonelectrolytes

• Do not conduct an electric current in aqueous solution or molten

• Many molecular compounds are nonelectrolytes– Ex sugar, rubbing alcohol

• Some very polar molecules become electrolytes when dissolved in water.

• Why? Because they ionize in solution– HCl + H2O --> H3O+ + Cl-

• Weak electrolyte - only a fraction of solute exists as ions

• Strong electrolyte - large portion of the solute exists as ions

Heterogeneous Aqueous Systems1. Difference in types of heterogeneous aqueous

systems is particle size

Suspensions - 1. particles settle out of solution2. can be filtered

ex muddy water

Colloids - 1. particles stay suspended in dispersion medium2. many are cloudy - may look clear when diluted3. exhibit Tyndall effect - scattering of light

ex - paints, glues, gelatin desserts, etc

Solutions - we already went over solutions

Colloidal Systems

Emulsions - Colloidal dispersion of liquids in liquids

needs an emulsifying agent

ex - soap

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