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Chapter 10States of Matter

Essential Question • What are physical &

chemical properties of liquids and solids?

• Standard 2h• Students will identify solids and liquids

held together by forces, and to relate these forces with boiling and melting points.

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Kinetic Molecular Theory (Ideal Gases)• 1. Gases move continuously.• 2. Particles extremely small.• 3. Forces between molecules negligible.• 4. Collisions are elastic (no loss of energy).• 5. Average kinetic energy of gas particles

same for all gases at same temperature.

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Gases, Liquids and Solids• Most gases monatomic.• Small molecules with covalent bonding.• Pure liquids composed of molecules with

covalent bonding. • All ionic compounds are solids. They conduct

electricity when heated, melted or aqueous.• Except for mercury, all metals are solid and

conduct electricity.

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The Liquid State• Viscosity: resistance of a liquid to flow.• Related to molecule shape.• Small molecules have low viscosities.• Large molecules have high viscosities.

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Properties of Liquids• Surface Tension: energy required to increase

the surface area of a liquid.• Liquids with stronger attractive forces

have a greater surface tension (ex: H2O).• A molecule in the middle of a liquid is

attracted equally in all directions. • Surface area minimized. • Light objects float.

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Surface Tension• Detergents or surfactants can lower

surface tension, causing water to wet a surface.

• This allows cleaning agent to “bind” to dirt molecules and carry away.

Hg pure H2O H2O with detergent

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Boiling Point• Liquid heated; vapor pressure

increases. • Boiling point (B.P.) = vapor pressure = external

pressure• Normal boiling point = temp

where vapor pressure of a liquid = 1 atm.

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Classification of Solids• Ionic solids - ions at lattice point in crystal.• Molecular solids - molecules at each lattice.• Covalent network solids - atoms at lattice

points; covalent bonds. • Ex: graphite & diamond.

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Graphite, an Allotrope of Carbon

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The Structure of

Diamond, an

Allotrope of Carbon

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Vaporization and Condensation• Vaporization: molecules of liquid break

away and enter the gas phase.• Condensation: molecules in gas phase

enter the liquid phase.

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Distillation• In simple distillation, a solution of two volatile

liquid compounds are heated to boiling. • The more volatile component is in higher

concentration in the vapor than in the liquid.• Separation technique for liquids.

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Distillation Apparatus

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Melting and Freezing• When solid is heated, particles vibrate

more vigorously and become liquid.• This process is called melting.• When a substance changes from a liquid

to a solid the process is called freezing.

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Water• Water is a unique substance.• Molecular bonding consists primarily of

hydrogen bonds which are quite strong.• Relatively high boiling point (100oC) and

melting point (0oC)• Moderate density (~1 g/mL)• High Specific Heat (4.184 J/g)• High Heat of Vaporization

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Properties of Water

• High surface tension• High capillarity (Hydrogen bonds).

Adhesion > cohesion.• Density of liquid > solid• ice floats• Due to hydrogen bonding, open

structure of ice.

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Solvent Properties of Water

• Highly polar, able to form hydrogen bonds.

• Good solvent for ionic compounds.