Water. Ice Liquid water’s density is greatest 4 o C. Ice has a 10% greater volume; therefore,...
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Transcript of Water. Ice Liquid water’s density is greatest 4 o C. Ice has a 10% greater volume; therefore,...
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.
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.
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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Demo Time