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