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20 Cards in this Set
- Front
- Back
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During the process of melting ice by adding heat, the temperature of the ice/liquid water slurry
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stays constant
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What is the vapor pressure of water at 100ºC?
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1 atm
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Consider the following compounds:
NH3 CH4 H2 How many of the compounds above exhibit London dispersion forces? |
all three
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Which of the following accounts for the unusually high boiling point of water?
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the hydrogen bonds in water
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Consider the following liquids with similar molar masses. Predict which has the weakest intermolecular attraction based only on vapor pressure data.
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butane (vapor pressure @ 20ºC = 1550 mm Hg)
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What is the strongest inermolecular force in a liquid containing molecules with H-O bonds?
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hydrogen bonds
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Increasing temperature; increases kenetic energy when Kenetic energy increases molecules begin to go further apart until free
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side note
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Changes of state of matter are:
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-physical changes
-no chemical bonds (intramolecular forces) are broken -energy supplied is used to break intermolecular bonds -intermolecular bonds are broken upon heating |
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Intermolecular forces: dispersion forces
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Intermolecular forces that occur between molecules.
London dispersion (present in all molecules) dipole-dipole (present in polar molecules) hydrogen bonding (present only in molecules containing H-F, -O, -H, and -N -H bonds) |
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The strongest of all intermolecular forces?
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hydrogen bonding
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Intermolecular Forces: Dispersion forces
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-induced dipole (temporary dipoles)
-weakest of all intermolecular forces -present in all molecules -increases w/increasing molar mass |
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Intermolecular Forces: Dipole-Dipole attractions
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-a result of permanent dipoles
-present in polar molecules (polar molecules, M not equal to 0) -10% the strength of a covalent bond |
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Intermolecular Forces: Hydrogen Bonds
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-Strong dipole-dipole forces
-hydrogen is bound to a highly electronegative atom: nitrogen, oxugen, or fluorine -bent structure -104.5º bond angle -exhibits strong H-bond -two nonbonding eletron pairs -two bonding electron pairs |
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Properties of ice
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Ice is less dense than water because of Hydrogen bonds
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Physical properties of water: Melting/Boiling Point
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Hydrogen bonds give water an exceptionally HIGH melting point and boiling point
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Some physical properties of Liquid that depend on intermolecular forces include:
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-Vapor Pressure: decreases as intermolecular foces increase
-melting/boiling point: increase as inermolecular forces increase |
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Vapor pressure:
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Pressure of a vapor present at equilibrium.
(Steady state at which the rate of condensation = the rate of evaporation) |
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Dispersion forces are the.........
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weakest
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There are 5 properties of liquids that are affected by intermolecular bonds:
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-Vapor pressure decreases as intermolecular forces increase
-Melting point and Boiling point increase as intermolecular forces increase -Viscosity increases as intermolecular forces increase -Surface tension increases as intermolecular forces increase |
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Summary
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-In general, the stronger the intermolecular forces, the higher the melting and boiling temperature of a substance
-energy is required to raise the temp of a substance -water displays many unique properties due to the presence of strong hydrogen bonds |
