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Chem ch 13:Liquids, solids, and intermolecular forces


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What is surface tension?
The energy or work required to increase the surface area of a liquid.
What are cohesive forces?
intermolecular forces between like molecules
What are adhesive forces?
intermolecular forces between unlike molecules
What is the relationship between adhesive and cohesive forces?
cohesive forces are stronger=liquid remains shape; adhesive forces are stronger= liquid spreads out
What are wetting agents?
Substances that reduce the surface tension of water and allow it to spread more easily
What is viscosity?
a liquids resistance to flow.
What is the relationship between molecular forces and temperature in relation to viscosity?
stronger the m.forces= stronger viscosity; viscosity decreases with increased temp due to high kinetic energies
What is vaporization/ evaporation?
change of a surface liquid into gaseous or vapor state.
What is enthalpy of vaporization?
The quantity of heat that must be absorbed if a certain quantity of liquid is vaporized at a constant temp. (endothermic/always pos.)
What is condensation?
conversion of gas or vapor to a liquid. (exothermix/ always neg)
What is dynamic equilibrium?
vaporization and condensation occur simultaneously, condition where amount of vapor remains constant
What is vapor pressure?
pressure exerted by a vapor in dynamic equilibrium with its liquid. increases with temp
What is the relationship between intermolecular forces, v.p. and volatility?
high v.p, low interm.forces= volatile; low v.p, high interm. forces= non-volatile
What is the vapor pressure curve?
vapor pressure as a function of temp.
What is boiling?
pressure exerted by escaping molecules equals that exerted by molecules of the atmosphere. vaporization occurs throughout liquid
What is normal boiling point?
temp. at which v.pressure of a liquid is = to 1 ATM
What is the critical point?
liquid and vapor are indistinguishable. density of liquid decreases, density of vapor increases, s. tension approaches 0
What is melting/melting point?
solid converted to a liquid/ temp at which this occurs
What is freezing/ freezing point?
liquid converted to a solid/ temp at which this occurs
What is enthalpy of fusion?
quanity of heat required to melt a solid
What is sublimation?
direct passage of molecules from solid to vapor state
What is deposition?
passage of molecules from vapor to solid state
What is enthalpy of sublimation?
quantity of heat required to convert solid to vapor
What is a phase diagram?
graph of conditions of temp and pressure at which solids, liquids, gases exist.
What is a triple point?
the unique temp at which the 3 states of matter coexist in equilibrium.
What is polymorphism?
existence of a solid substance in more than one form
How is a hydrogen bond formed? (intermolecular)
H atom is bonded to a electronegative atom in 1 molecule and another neighboring molecule
What is lattice energy?
energy given off when seperated gaseous ions come together to form 1 mole of ionic solid
What is body centered cubic?
a structural particle of the crystal is found at the center of the cube as well as the corners.
What is face centered cubic?
a structural particle at the center of each face as well as the corners.
What is a unit cell?
a parallelepiped (3 dimensional figure having 6 faces) that can be used to generate the entire lattice by simple straight displacements
What is a network covalent solid?
covalent bond between 2 different atoms
What are the characteristics of a network solid?
Compound is harder, and increase in melting point
What is the relationship b/w lattice energy and dissolving?
higher lattice energy= harder to dissolve, lower lattice energy=easier
What are two types of solids?
crystalline and amorphious
What is the unit cell?
smallest unit repeated in 3 dimensions, makes up entire crystal
What is coordination number?
# of nearest neighbors surrounding a particle in a crystal

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