lesson 12.2 and 12.4 laws of attraction phase change
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Lesson 12.2 and 12.4
Laws of Attraction
Phase Change
Intramolecular Forces
Force Model Basis Example
Ionic Cations and anions
NaCl
Covalent Shared electrons H2
Metallic Metal cations and mobile electrons
Fe
Dispersion Forces
Weak Force
Temporary shift in electron density clouds
Explains State of Matter of Halogens
Small to Large
F2 (g)
Cl2 (g)
Br2 (l)
I2 (s)
Dipole-dipole Forces
Permanent forces
Positive – Negative Poles
Hydrogen Bonds
Dipole-dipole attraction
some examples large
electronegative
H-F H-O
H-N H-S
Room TemperatureH2O is liquid NH3 is gas
Questions
Explain what determines a substance’s state at a given temperature.
Compare intermolecular and intramolecular forces.
Which molecules can form hydrogen bonds?
a. H2 b. H2S c. HCl d. HF
Questions
Explain what determines a substance’s state at a given temperature.
Intermolecular forces – solid very strong, liquid weaker, gas has none
Compare intermolecular and intramolecular forces.
Intramolecular hold particles together, intermolecular between particles
Which molecules can form hydrogen bonds?
a. H2 b. H2S c. HCl d. HF
Phase Change
Phase Changes that Require Energy
Melting – liquid is warmer than ice, heat is transferred
Vaporization – liquid to vapor or gas gradually
Sublimation – direct from solid to gas
Phase Change Release Energy
Freezing – heat is removed
Condensation – what happens to the glass of ice cold lemonade on a hot day?
Phase Diagram
Triple Point
Phase Diagram Questions
Explain what the triple point and the critical point on a phase diagram supplies
Determine the phase of water at 75.00 C and 3.00 atm.
Explain what the triple point and the critical point on a phase diagram supplies
Triple point is where all 3 phases can coexist.
Critical point is temp and pressure above which a substance is not a liquid
Determine the phase of water at 75.00 C and 3.00 atm. liquid
Questions
Explain how the addition or removal of energy can cause a phase change.
Explain the difference between the processes of melting and freezing.
Compare disposition and sublimation.
Questions
Explain how the addition or removal of energy can cause a phase change.
Add Energy, increase Kinetic Energy, less intermolecular forces
Remove Energy, decrease Kinetic Energy, increase intermolecular forces
Explain the difference between the processes of melting and freezing.
Freezing: Liquid to solid, release EnergyMelting: Solid to liquid, need to input EnergyCompare disposition and sublimation.Sublimation: solid to vapor directly, skips
liquid phaseDisposition: Vapor to solid, without liquid
phase
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