Chem 141 exam #4 study guide 2025
Questions and Answers
Intermolecular forces - --CORRECT ANSWER--IM forces exist among all the
particles that compose matter. The state of a sample of matter- solid, liquid, or gas-
depends on the magnitude of intermolecular forces among the constituent particles
relative to the amount of thermal energy in the sample.
Thermal energy - --CORRECT ANSWER--When thermal energy is high relative
to intermolecular forces, matter tends to be gaseous.
When thermal energy is low relative to the intermolecular forces, matter tends to
be liquid or solid.
The three states of water: - --CORRECT ANSWER--Gas (Steam): 100 C. Density:
5.90 x 10^-4 g/cm^3. Molar volume: 30.5L
Liquid (water): 20 C. Density: 0.998 g/cm^3. Molar volume: 18.0 mL.
Solid (Ice): Temperature: 0 C. Density: 0.917 g/cm^3. Molar volume: 19.6 mL.
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,Density of solid water is less than the density of liquid water, which is atypical
behavior. This is because of the unique crystal structure of ice.
Properties of the states of matter: - --CORRECT ANSWER--Gas: Density= low,
shape= indefinite, volume= indefinite, strength to intermolecular forces= weak
Liquid: Density=high, shape= indefinite, volume= definite, strength of
intermolecular forces= moderate.
Solid: Density= high, shape= definite, volume= definite, strength to
intermolecular forces= strong.
Molecules with partial or temporary charges are: - --CORRECT ANSWER--
Attracted to each other because their potential energy decreases as they get closer
together. But even the strongest intermolecular forces are generally much weaker
than bonding forces.
Dispersion forces: - --CORRECT ANSWER--An intermolecular forces exhibited
by all atoms and molecules that result from fluctuations in the electron
distribution. These forces occur because of fluctuations on the electron
distribution within molecules or atoms. There is a fleeting charge separation called
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, an instantaneous dipole or temporary dipole, which attract other instantaneous
dipoles (positive attracts negative and vice versa).
- A larger electron cloud can result in a greater dispersion forces.
- Dispersion force increases with increasing molar mass.
- Molecules with a longer shape also have
Dipole dipole: - --CORRECT ANSWER--Exists between all molecules that are
polar.
- Acetone has a permanent dipole which interacts by having the positive end of
one molecule attract the negative end of another.
- Boiling point increases with increasing dipole moment.
In general, polar liquids: - --CORRECT ANSWER--Polar liquids tend to be
miscible with water, while nonpolar liquids are not. "like dissolves like"
Hydrogen bonding: - --CORRECT ANSWER--Polar molecules that contain
hydrogen atoms bonded directly to small electronegative atoms, most importantly:
Fluorine, Oxygen, or Nitrogen.
*Carbon does not have hydrogen bonding*
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Questions and Answers
Intermolecular forces - --CORRECT ANSWER--IM forces exist among all the
particles that compose matter. The state of a sample of matter- solid, liquid, or gas-
depends on the magnitude of intermolecular forces among the constituent particles
relative to the amount of thermal energy in the sample.
Thermal energy - --CORRECT ANSWER--When thermal energy is high relative
to intermolecular forces, matter tends to be gaseous.
When thermal energy is low relative to the intermolecular forces, matter tends to
be liquid or solid.
The three states of water: - --CORRECT ANSWER--Gas (Steam): 100 C. Density:
5.90 x 10^-4 g/cm^3. Molar volume: 30.5L
Liquid (water): 20 C. Density: 0.998 g/cm^3. Molar volume: 18.0 mL.
Solid (Ice): Temperature: 0 C. Density: 0.917 g/cm^3. Molar volume: 19.6 mL.
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,Density of solid water is less than the density of liquid water, which is atypical
behavior. This is because of the unique crystal structure of ice.
Properties of the states of matter: - --CORRECT ANSWER--Gas: Density= low,
shape= indefinite, volume= indefinite, strength to intermolecular forces= weak
Liquid: Density=high, shape= indefinite, volume= definite, strength of
intermolecular forces= moderate.
Solid: Density= high, shape= definite, volume= definite, strength to
intermolecular forces= strong.
Molecules with partial or temporary charges are: - --CORRECT ANSWER--
Attracted to each other because their potential energy decreases as they get closer
together. But even the strongest intermolecular forces are generally much weaker
than bonding forces.
Dispersion forces: - --CORRECT ANSWER--An intermolecular forces exhibited
by all atoms and molecules that result from fluctuations in the electron
distribution. These forces occur because of fluctuations on the electron
distribution within molecules or atoms. There is a fleeting charge separation called
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
, an instantaneous dipole or temporary dipole, which attract other instantaneous
dipoles (positive attracts negative and vice versa).
- A larger electron cloud can result in a greater dispersion forces.
- Dispersion force increases with increasing molar mass.
- Molecules with a longer shape also have
Dipole dipole: - --CORRECT ANSWER--Exists between all molecules that are
polar.
- Acetone has a permanent dipole which interacts by having the positive end of
one molecule attract the negative end of another.
- Boiling point increases with increasing dipole moment.
In general, polar liquids: - --CORRECT ANSWER--Polar liquids tend to be
miscible with water, while nonpolar liquids are not. "like dissolves like"
Hydrogen bonding: - --CORRECT ANSWER--Polar molecules that contain
hydrogen atoms bonded directly to small electronegative atoms, most importantly:
Fluorine, Oxygen, or Nitrogen.
*Carbon does not have hydrogen bonding*
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