IMF's, Liquids and Solids, phase changes and Water
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107 Terms
What are intermolecular forces?
forces that occur between molecules
What are intramolecular forces?
forces that occur inside molecules
Which is stronger, intramolecular or intermolecular forces?
intramolecular forces
What are the three types of intermolecular forces?
Dispersion, dipole, hydrogen bonding
What is the weakest intermolecular force?
Dispersion
What is the strongest intermolecular force?
Hydrogen bonding
Covalent, ionic, and metallic bonds are stronger than dispersion, dipole, and hydrogen bonds. True or False?
True
What are the 3 types of intramolecular forces?
Covalent, ionic, and metallic
What are dispersion and dipole sometimes referred as?
Vander Waals forces
What are dispersion forces?
weak forces that result from temporary shifts in density of electrons in electron clouds
Dispersion forces occur in symmetrical molecules
True
Where are dispersion forces important?
in nonpolar substances and noble gases
What are alternate names for dispersion forces?
London Forces and induced dipole forces
How do dispersion forces work?
When 2 nonpolar molecules encounter one another, attractions and repulsions lead to distortions in their electron clouds, inducing “momentary dipoles”
How do you determine which molecule has a stronger dispersion force?
Which ever molecule has more electrons
Why do molecules with more electrons have stronger dispersion forces?
There is more distortion and its easier for the molecule to stick together
Large nonpolar molecules are less polarizable
False
What are dipole interactions?
attractions between oppositely charged regions of polar molecules
What do dipole interactions hold together?
polar molecules
Which is stronger, Dipole interactions or dispersion forces?
Dipole Interactions
Which is stronger, Ionic bonds or dipole interactions?
ionic bonds
What are hydrogen bonds?
a dipole interaction that occurs between molecules containing hydrogen bonded to a small, highly electronegative atom with at least one electron pair
What type of molecules do hydrogen bonds hold together?
Polar
What elements, when paired with hydrogen, create hydrogen bonds?
N, O, F
Which is weaker, Hydrogen bonds or ionic bonds?
Hydrogen bonds
Which is stronger, Hydrogen bonds or dipole forces?
Hydrogen bonds
How do hydrogen bonds affect boiling point?
the stronger the bond, the higher the boiling point
Which has lower forces of attraction, nonpolar or polar molecules?
nonpolar molecules
How do you determine the increasing strength of intermolecular forces?
Hydrogen bonds are the strongest, then polar molecules, then ones with more electrons, and the weakest are non polar molecules
Liquids and solids have higher IMF’s than gases at the same temperature
True
How many more times are liquids more dense than their vapor?
1000
What has more fluidity, liquids or gases?
Gases
What states of matter have fluidity?
Gases and liquids
What is viscosity?
a measure of resistance to flow
How is viscosity determined?
by IMF’s, size of molecules, and temperature
Do solids or liquids have stronger IMF’s at the same temperature?
Solids
How much more dense are solids than liquids?
10% more dense
When a molecule is larger, does it have more or less viscosity?
more viscosity
When a molecule has a higher temperature, does it have more or less viscosity?
less viscosity
What are the properties of a solid?
rigid, fixed shape, fixed volume, cannot be squashed
What are the properties of a liquid?
not rigid, no fixed shape, fixed volume, cannot be squashed
What are the properties of a gas?
not rigid, no fixed shape, no fixed volume, can be squashed
Substances in equilibrium do not change back and forth between states are equal speeds
False
What is equilibrium?
a dynamic condition in which 2 opposing changes occur at equal rates in a closed system
How is vapor pressure determined?
The IMF’s of the liquid and the temperature of the liquid
Do low boiling points have high or low vapor pressure?
High vapor pressure
Do high boiling points have high or low vapor pressure?
low vapor pressure
What is equilibrium vapor pressure?
the pressure exerted by a vapor over a liquid
The higher the IMF the lower the vapor pressure
True
The higher the temperature the higher the vapor pressure
True
What are volatile liquids?
Liquids with weak forces of attraction between particles
Volatile liquids have (high/low) vapor pressure
high
Melting
changing from a solid to a liquid
Vaporization
changing from liquid to gas
Sublimation
changing from a solid directly to a gas
Boiling
the conversion of a liquid to a vapor within the liquid as well as at its surface
What is boiling point?
the temperature at which equilibrium vapor pressure of the liquid equals atmospheric pressure
Atmospheric pressure and boiling point are proportionally related
True
Altitude and boiling point are proportionally related
False, they are inversely related
What phases are endothermic?
melting, vaporization, boiling, sublimation
what phase changes are exothermic?
freezing, condensation, deposition
Freezing
changing from a liquid to a solid
what is freezing point?
the temperature at which a substance changes from a liquid to a solid
Condensation
changing from a gas to a liquid
Deposition
changing from a gas directly to a solid
What are heating curves?
during a phase change, the temperature remains constant. the energy goes to break bonds, not making molecules move faster
KNOW HOW TO IDENTIFY HEATING CURVES ON A GRAPH
KNOW HOW TO IDENTIFY HEATING CURVES ON A GRAPH
Why does the temperature remain constant during a phase change?
the energy goes into breaking bonds
What is energy?
the ability to do work or produce heat
What are the 2 forms of energy?
Potential and Kinetic
What is potential energy?
energy due to the composition or position of an object
What is kinetic energy?
energy of motion
Chemical systems don’t involve both kinetic energy and potential energy
False
Temperature and Kinetic energy are proportionally related
True
What is chemical potential energy?
the energy ithat is stored in the chemical bonds of a substance, and happens because of the position of the atoms/molecules
What is thermal energy?
Kinetic energy, usually of particles, proportional to kelvin temperature
What is the law of conservation of energy?
energy is never created or destroyed, although it can be converted from one form to another
Temperature and heat are related but not identical
True
What is temperature?
the average kinetic energy of the particles in a sample of matter
What is heat?
the total energy that transfers between 2 objects due to temperature difference between them
Heat is only transferred from a hot object to a cold object (never the other way)
True
Are exothermic reactions negative or positive in equations?
negative
are endothermic reactions positive or negative in equations?
positive
What equations can help determine if a reaction is endo/exothermic?
Energy products-energy reactants
What is a calorie?
the amount of energy required to raise the temperature of 1g of pure water by 1 degree Celsius
Nutritional Calorie is capatlizied
True
How many calories is 1 nutritional Calorie?
1000 calories/ 1 kilocalorie
What is the unit of energy and heat?
Joule
How many calories are equal to 1 Joule?
0.2390 calories
How many joules is equal to 1 calorie?
4.184 joules
What is specific heat capacity (or specific heat)?
The amount of energy needed to change the temperature of 1g of a substance by 1 degree C (or 1 degree K)
Metals do not transfer energy faster
False
What is the equation for specific heat?
Q=Cm(delta)T
What is Q in the specific heat equation?
Heat
What is m in the specific heat equation?
mass
What is C in the specific heat equation?
specific heat
what is (delta)T in the specific heat equation?
Change in temperature; Tfinal-Tinitial
The substance that has the lower specific heat will have a larger change in temperature
True
Why does the substance that has the lower specific heat have a larger change in temperature?
It requires less heat to raise the temperature of the substance
Exothermic
energy flows out of the system