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CHM 2046 Exam 2 Dr. Jones

Terms in this set (57)

dilute solution (Section 13.5)
A solution that contains a very small amount of solute relative to the amount of solvent.
concentrated solution (Section 13.5)
A solution that contains a large amount of solute relative to the amount of solvent.
molarity (M) (Section 13.5)
A means of expressing solution concentration as the number of moles of solute per liter of solution
molality (m) (Section 13.5)
A means of expressing solution concentration as the number of moles of solute per kilogram of solvent.
parts by mass (Section 13.5)
A unit for expressing solution concentration as the mass of the solute divided by the mass of the solution multiplied by a multiplication factor.
percent by mass (Section 13.5)
A unit for expressing solution concentration in parts by mass with a multiplication factor of 100%.
parts per million (ppm) (Section 13.5)
A unit for expressing solution concentration in parts by mass in which the multiplication factor is 10ˆ6.
parts per billion (ppb) (Section 13.5)
A unit for expressing solution concentration in parts by mass in which the multiplication factor is 10ˆ9.
parts by volume (Section 13.5)
A unit for expressing solution concentration as the volume of the solute divided by the volume of the solution multiplied by a multiplication factor.
mole fraction (Xsolute) (Section 13.5)
A means of expressing solution concentration as a number of moles of solute per moles of solution.
mole percent (mol%) (Section 13.5)
A means of expressing solution concentration as the mole fraction multiplied by 100%.
colligative property (Section 13.6)
Amount of solute dependent; A property that depends on the amount of a solute but not on the type.
Raoult's law (Section 13.6)
An equation used to determine the vapor pressure of a solution; Psoln = Xsolv • P˚solv.
vapor pressure lowering (∆P) (Section 13.6)
The change in vapor pressure that occurs in pure substance upon addition of a solute.
ideal solution (Section 13.6)
A solution that follows Raoult's law at all concentrations for both solute and solvent.
freezing point depression (Section 13.6)
The effect of a solute that causes a solution to have a lower melting point than the pure solvent.
boiling point elevation (Section 13.6)
The effect of a solute that causes a solution to have a higher boiling point than the pure solvent.
osmosis (Section 13.6)
The flow of solvent from a solution of lower solute concentration to one of higher solute concentration.
semipermeable membrane (Section 13.6)
A membrane that selectively allows some substances to pass through but not others.
osmotic pressure (Section 13.6)
The pressure required to stop osmotic flow.
van't Hoff factor (i) (Section 13.7)
The ratio of moles of particles in a solution to moles of formula units dissolved.
colloidal dispersion (colloid) (Section 13.8)
A mixture in which a dispersed substance is finely dived but not truly dissolved in a dispersing medium.
Tyndall effect (Section 13.8)
The scattering of light by a colloidal dispersion.
rate law (Section 14.3)
A relationship between the rate of a reaction and the concentration of the reactants.
rate constant (k) (Section 14.3)
A constant of proportionality in the rate law.
reaction order (n) (Section 14.3)
A value in the rate law that determines how the rate depends on the concentration of reactants.
overall order (Section 14.3)
The sum of the orders of all reactants in a chemical reaction.
integrated rate law (Section 14.4)
A relationship between the concentrations of the reactants in a chemical reaction and time.
half-life (t1/2) (Section 14.4)
The time required for the concentration of a reactant or the amount of a radioactive isotope to fall to one-half of its initial value.
Arrhenius equation (Section 14.5)
An equation that relates the rate constant of a reaction to the temperature, the activation energy, and the frequency factor: k = Ae ^(-Ea/RT).
activation energy (Ea) (Section 14.5)
An energy barrier in a chemical reaction that must be overcome for the reactants to be converted into products.
frequency factor (A) (Section 14.5)
The number of times that reactants approach the activation energy per unit time.
activated complex (transition state) (Section 14.5)
A high-energy intermediate state between reactant and product.
exponential factor (Section 14.5)
A number between zero and one that represents the fraction of molecules that have enough energy to make it over the activation barrier on a given approach.
Arrhenius plot (Section 14.5)
A plot of natural log of the rate constant (In K) versus the inverse of the temperature in kelvins (1/T) that yields a straight line with a slope of -Ea/R and a y-intercept of In A.
collision model (Section 14.5)
A model of chemical reactions in which a reaction occurs after a sufficiently energetic collision between two reactants molecules.
orientation factor (Section 14.5)
A factor in collision theory (usually between 0 and 1) that represents the fraction of collisions having an orientation that can allow the reaction to occur.
collision frequency (Section 14.5)
A factor in collision theory that represents the number of collisions that occur per unit time.
reaction mechanism (Section 14.6)
A series of individual chemical steps by which an overall chemical reaction occurs.
elementary step (Section 14.6)
An individual step in a reaction mechanism.
reaction intermediate (Section 14.6)
Species that form in one step of a reaction mechanism and are consumes in another.
molecularity (Section 14.6)
The number of reaction particles involved in an elementary step.
unimolecular (Section 14.6)
Describes a reaction that involves only one particle that goes on to from products.
bimolecular (Section 14.6)
An elementary step in a reaction that involves two particles, either the same species or different, that collide and go on to form products.
termolecular (Section 14.6)
An elementary step of a reaction in which three particles collide and go on to form products.
rate-determining step (Section 14.6)
The step in a reaction mechanism that occurs much more slowly than any of the other steps.
catalyst (Section 14.7)
A substance that is not consumed in a chemical reaction that increases the rate of the reaction by providing an alternate mechanism in which the rate-determining step that has a smaller activation energy.
homogeneous catalysis (Section 14.7)
Catalysis in which the catalyst exists in the same phase as the reactants.
heterogeneous catalysis (Section 14.7)
Catalysis in which the catalyst and the reactants exist in different phases.
hydrogenation (Section 14.7)
The catalyzed addition of hydrogen to alkene double bonds to make single bonds.
enzyme (Section 14.7)
A biochemical catalyst made of protein that increases the rates of biochemical reactions.
active site (Section 14.7)
The specific area of an enzyme at which catalysis occurs.
substrate (Section 14.7)
The reactant molecule of a biochemical reaction that binds to an enzyme at the active site.
reversible (Section 15.2)
As applied to a reaction, the ability to proceed in either the forward or the reverse direction.
dynamic equilibrium (Section 15.2)
The point at which the rate of the reverse reaction or process equals the rate of the forward reaction or process.
equilibrium constant (K) (Section 15.3)
The ratio, at equilibrium, of the concentrations of the products of a reaction raised to their stoichiometric coefficients to the concentration of the reactants raised to their stoichiometric coefficient.
law of mass action (Section 15.3)
A law regarding the relationship between the balanced chemical equation and the expression of the equilibrium constant.
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