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Chem 1212: Chapters 12-14
Gas Laws through Solutions
62
Chemistry
Undergraduate 1
09/16/2010

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Term
Boyle's Law
Definition
P1V1=P2V2
Term
Charles' Law
Definition
V1/T1=V2/T2
Term
Combined Gas Law
Definition
P1V1/T1=P2V2/T2
Term
Avogadro's Law
Definition
At the same temperature and pressure, equal volumes of all gases contain the same number of molecules.
Term
Standard Molar Volume
Definition
22.4 L -- One mole of an ideal gas occupies 22.4 L at 0C and 1 atm of pressure.
Term
Ideal Gas Equation
Definition
PV=nRT
Term
Dalton's Law of Partial Pressures
Definition
The total pressure exerted by a mixture of ideal gases is the sum of the partial pressures of those gases.
Term
Vapor Pressure
Definition
Pressure exerted by its gaseous molecules in equilibrium with the liquid.
Term
Kinetic-Molecular Theory
Definition
1. Gases consist of discrete molecules. The individual molecules are very small and far apart relative to their sizes.

2. Gaseous molecules are in continuous, rapid random, straight-line motion with varying velocities.

3. The collisions between gas molecules and with the walls of the container are elastic; the total energy is conserved during a collision.

4. Between collisions, the molecules exert no attractive or repulsive forces on one another; each molecule travels in a straight line with a constant velocity.
Term
Root Mean Square
Definition
Urms=sq rt(3RT/Mm)

R=8.314 kg m2/s2 K mol

Molar mass, Mm, must be in KG/mol
Term
Effusion
Definition
Gases exiting through the walls of a container with porous walls.
Term
Diffusion
Definition
The movement of a substance into a space or the mixing of one substance with another.
Term
Ratio of Rate of Effusion
Definition
R1/R2=sqrt(M2/M1) OR (D2/D1)
Term
Deviations from Ideality
Definition
When molecules become close together through increased T or P -- intermolecular forces become important.
Term
Miscible Liquids
Definition
Diffuse into each other; they are soluble in each other and form homogeneous solutions.
Term
Intermolecular Forces
Definition
Forces between (among) individual particles (atoms, ions, molecules).
Term
Ion-Ion Interactions
Definition
Force of attraction between two oppositely charged ions is governed by Coulomb's Law:

F=abs(q1q2)/r2

F=magnitude of force
r=distance in m
q1,q2=charges on bodies (coulombs)
Term
Intermolecular Interaction Strengths
Definition
I-I>HB>D-D>>LF
Term
Dipole-Dipole
Definition
Occur between the + end of one polar molecule and the - end of the other.
Term
Hydrogen Bonding
Definition
Especially strong D-D interaction. Occurs between an H atom in one molecule (attached to an F, O, or N), and an F, O, or N atom in another molecule.
Term
Dispersion Forces (London Forces)
Definition
Present in all substances. ONLY kind of interactions for nonpolar substances. Result from the attraction of the nucleus of one atom for the electron cloud of another atom (in a different molecule). They increase with increasing polarizability, the ability of an electron cloud to be distorted. Polarizability increases with increasing numbers of electrons and therefore with increasing sizes of molecules.
Term
Ion-Dipole Interactions
Definition
Ion and Dipole. Weaker than Dipole-Dipole.
Term
Change in EN
Definition
Nonpolar: 0-0.5
Polar: 0.5-2.0
Ionic: > 2.0
Term
Viscosity
Definition
Resistance to flow. One measure of the forces of attraction within a liquid. Honey = high viscosity; gasoline = low viscosity.
Term
Surface Tension
Definition
Measure of the inward forces that must be overcome to expand the surface of a liquid. Molecules on the surface are attracted only toward the interior, while those on the interior are attracted equally in all directions.
Term
Capillary Action
Definition
Capillary Rise: Adhesive Forces > Cohesive Forces
Capillary Fall: Cohesive Forces > Adhesive Forces
Term
Evaporation
Definition
Process by which molecules escape from the surface of a liquid (vaporize). Occurs more rapidly as temperature increases because a greater fraction of molecules possess the necessary escape velocity and kinetic energy.
Term
LeChatelier's Principle
Definition
A system at equilibrium, or changing toward equilibrium, responds in the way that tends to relieve or "undo" any stress placed on it.
Term
Vapor Pressure
Definition
Pressure exerted by the vapor of the liquid on its surface at equilibrium in a closed container. Because vapor pressures increase as temperature increases, evaporation occurs more rapidly as T increases.
Term
Boiling Point
Definition
Temperature at which the vapor pressure of the liquid equals the applied (usually atmospheric) pressure.
Term
Distillation
Definition
Process by which a mixture or solution is separated into its components on the basis of differences in BPs of the components.
Term
Specific Heat
Definition
Amount of heat required to raise the T of 1g of a substance 1C with no change in state.

Q=mC(change in T)
Term
Molar Heat Capacity
Definition
Amount of heat required to raise the temperature of 1 mol of a substance 1C with no change in state.

Q=mol x molar heat capacity x change in T
Term
Heat of Vaporization
Definition
Amount of heat that must be absorbed to convert 1g of a liquid at its BP to a gas with no change in temperature. Usually J/g.
Term
Heat of Condensation
Definition
Reverse of Heat of Vaporization. Amount of heat that must be released to liquefy 1g of a gas at its condensation (BP) with no change in T.
Term
Molar Heat of Vaporization
Definition
The amount of heat that must be absorbed to convert one mole of a liquid at its BP to a gas with no change in T.
Term
Molar Heat of Condensation
Definition
Reverse of molar heat of vaporization.
Term
Melting Point
Definition
Temperature at which liquid and solid coexist at equilibrium under a pressure of 1 atm.
Term
Heat of Fusion
Definition
The amount of heat required to melt 1g of a solid at its melting point with no change in T. Endothermic.
Term
Heat of Crystallization
Definition
Amount of heat liberated by the crystallization of one gram of liquid at its freezing point. Exothermic.
Term
Specific Heat of Water
Definition
4.18 J/gC
Term
Density of Water
Definition
1.00 g/mL
Term
Specific Heat of Ice
Definition
2.09 J/gC
Term
Sublimation
Definition
Conversion of a solid directly into vapor. Dry Ice is solid CO2. The white vapors are due to water condensing in the very cold gaseous CO2 near the solid.
Term
Deposition
Definition
Vapor directly to solid.
Term
Triple Point
Definition
Point at which three phases of a substance can coexist in equilibrium.
Term
Critical Temperature
Definition
Temperature above which a gas cannot be liquefied, i.e., the temperature above which the liquid and gas do not exist as distinct phases.
Term
Amorphous Solids
Definition
Have no well-defined ordered structure. Waxes, asphalt, and glass.
Term
Critical Pressure
Definition
Pressure required to liquefy a gas at its critical temperature.
Term
Critical Point
Definition
The combination of critical temperature and critical pressure.
Term
Metallic Solids
Definition
Metals.
Term
Ionic Solids
Definition
Consist of positive and negative ions arranged in a definite crystal structure. Attractions between oppositely charged ions are strong.
Term
Molecular Solids
Definition
Consist of discrete molecules that occupy positions in unit cells. Intermolecular forces are relatively weak. London Forces and D-D.
Term
Covalent Solids
Definition
Individual atoms are covalently bonded to several other atoms; thus they are very hard with very high melting points. Diamond, graphite, SO2 (sand), SiC.

Molecular less than Metallic less than Ionic less than Covalent
Term
Two major factors affect dissolution of solutes
Definition
Enthalpy and Entropy
Term
Crystal Lattice Energy
Definition
Measure of attractive forces among particles of a solid. Increases as the charges on ions increase. The higher the CLE, the stronger the bond.
Term
Enthalpy
Definition
Change of energy content of solution (ChangeHsoln). If change Hsoln is exothermic (<0), dissolution is favored. -changeH
Term
Entropy
Definition
Change in disorder (randomness( of the solution. ChangeSmixing.

NaCl --> Na+ + Cl- increasing entropy +changeS
Term
Molality
Definition
mol solute/kg solvent
Term
Molarity
Definition
mol solute/L solution
Term
Mole Fraction
Definition
Xa=(# mols of A)/(# mols of A + # mols of B)
Term
Percent by Mass
Definition
g solute/100 g solution
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