Chemistry II ACS Exam questions and answers

  phase - Correct Answers: a physically distinct and homogenous part of a system intermolecular forces - Correct Answers: the attractive and repulsive forces among the particles-molecules, atoms or ions in a sample of matter heat of vaporization - Correct Answers: the enthalpy change occurring when 1 mol of a liquid substance vaporizes heat of fusion - Correct Answers: the enthalpy change occurring when 1 mol of a solid melts heat of sublimation - Correct Answers: the enthalpy change occurring when 1 mol of solid substance changes directly into a gas heating-cooling curve - Correct Answers: a plot of temperature vs. time for a substance when heat is absorbed or released by the system at a constant rate vapor pressure - Correct Answers: the pressure exerted by a vapor at equilibrium with its liquid in a closed system ion-dipole force - Correct Answers: the intermolecular attractive force between an ion and a polar molecule dipole-dipole force - Correct Answers: the intermolecular attractive force between oppositely charged poles of nearby polar molecules dipole-induced dipole - Correct Answers: the intermolecular attractive forces between a polar molecule and the oppositely charged pole it induces in a nearby molecule hydrogen bond - Correct Answers: a type of dipole-dipole force that arises between molecules that have an H atom bonded to a small highly electronegative atom with lone pairs, usually N, O, or F polarizability - Correct Answers: the ease at which a particles electron cloud can be distorted london dispersion forces - Correct Answers: the intermolecular attraction between all particles as a result of instantaneous polarizations of their electron cloud; the intermolecular force primarily responsible for the condensed state of nonpolar substances surface tension - Correct Answers: the energy required to increase the surface area of a given liquid by a given amount capillarity - Correct Answers: a property that results in a liquid rising through a narrow space against the pull gravity viscosity - Correct Answers: a measure of the resistance of a liquid to flow crystalline solid - Correct Answers: a solid with well-defined shape because of the orderly arrangement of the atoms, molecules or ions amorphous solid - Correct Answers: a solid that has poorly-defined shape because it lacks extensive molecular-level ordering of its particles lattice - Correct Answers: the three-dimensional arrangement of points created by choosing each point to be at the same location within each particle of a crystal, thus the lattice consists of all points with identical surroundings solute - Correct Answers: the substance that dissolves in the solvent solvent - Correct Answers: the substance in which the solute(s) dissolve miscible - Correct Answers: soluble in any proportion solubility - Correct Answers: the maximum amount of a solute that dissolves in a fixed quantity of a particular solvent at a specified temperature like-dissolves-like rule - Correct Answers: an empirical observation stating that substance having similar kinds of intermolecular forces dissolve in eachotehr hydration shell - Correct Answers: the oriented cluster of water molecules that surrounds an ion in an aqueous solution heat of solution - Correct Answers: the enthalpy change occurring when a solution forms from solute to solvent. the sum of the enthalpies from separating solute and solvent substances and mixing them saturated solution - Correct Answers: a solution that contains the maximum amount of dissolved solute at a given temperature unsaturated solution - Correct Answers: a solution in which more solute can be dissolved at the given temperature supersaturated solution - Correct Answers: an unstable solution in which more solute is dissolved than in a saturated solution henry's law - Correct Answers: a law stating that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the gas molality (m) - Correct Answers: a concentration term expressed as number of moles of solute dissolved in 1 kg of solvent (assume the solvent is water if not told) mass percent - Correct Answers: the fraction by mass expressed as a percentage. a concentration term expressed as the mass of solute dissolved in 100 parts by mass of solution volume percent - Correct Answers: a concentration term defined as the volume of solute in 100 volumes of solution mole fraction (x) - Correct Answers: a concentration term expressed as the ratio of moles of one component of a mixture to the total moles present colligative property - Correct Answers: a property of solution that depends on the number, not the identity, of solute particles (ex. boiling point elevation, freezing point expression, osmotic pressure, and vapor pressure lowering) electrolyte - Correct Answers: a substance that conducts a current when it dissolves in water. a mixture of ions, in which the electrodes of an electrochemical cell are immersed, that conducts a current nonelectrolyte - Correct Answers: a substance whose aqueous solution does not conduct an electrical current vapor pressure lowering - Correct Answers: the lowering of the vapor pressure of a solvent caused by the presence of dissolved solute particles ideal solution - Correct Answers: a solution whose vapor pressure equals the mole fraction of the solvent time the vapor pressure of the pure solvent; approximated only by very dilute solutions boiling point elevation - Correct Answers: the increase in the boiling point of a solvent caused by the presence of a dissolved solute freezing point depression - Correct Answers: the lowering of the freezing point of a solvent due to the presence of a dissolved solute osmotic pressure - Correct Answers: the pressure that results from the ability of solvent, but not solute, particles to cross a semipermeable membrane. the pressure required to prevent the net movement of solvent across the membrane instantaneous rate - Correct Answers: the reaction rate at any particular time, given by the slope of a tangent to a plot of reactant concentration vs. time reaction orders - Correct Answers: the exponent of a reactant concentration in a rate law that shows how the rate is affected by changes in that concentration integrated rate law - Correct Answers: a mathematical expression for reactant concentration as a function of time half-life - Correct Answers: in chemical processes, the time required for half the initial reactant concentration to be consumed. in nuclear processes, the time required for half of the initial number of nuclei in the sample to decay collision theory - Correct Answers: a model that explains reaction rate as based on the number, energy, and orientation of colliding particles activation energy - Correct Answers: the minimum energy with which molecules must collide to react transition state theory - Correct Answers: a model that explains how the energy of reactant collisions is used to form a high-energy transitional species that can change to reactant or product catalyst - Correct Answers: a substance or mixture that increases the rate of the reaction without being used up in the process reaction intermediate - Correct Answers: a substance that is formed and used up during the overall reaction and therefore does not appear in the overall reaction equation le chateliers principle - Correct Answers: a principle stating that if a system in a state of equilibrium is disturbed, it will undergo a change that shifts its equilibrium position in a direction that reduces the effect of the disturbance Arrhenius acid-base - Correct Answers: a model of acid-base behavior in which an acid is a substance that has H in its formula and dissociated in water to yield H3O+, and a base is a substance that has OH in its formula and yield OH- in water neutralization - Correct Answers: process that occurs when an H+ ion forms from an acid combines with an OH- ion from a base to form H2O acid-dissociation - Correct Answers: an equilibrium constant for the dissociation of an acid (HA) into H2O to yield the conjugate base (A-) and H3O+ pH - Correct Answers: the negative common log of [H3O+] acid-base indicator - Correct Answers: an organic molecule whose color is different in acid an in base and is used to monitor the equivalence point of a titration or the pH of a solution Bronsted-Lowry acid-base definition - Correct Answers: a model of acid-base behavior based on proton transfer proton donor - Correct Answers: acid proton acceptor - Correct Answers: base conjugate acid-base pair - Correct Answers: two species related to each other through the gain or loss of a proton; the acid has one more proton that its conjugate base polyprotic acid - Correct Answers: an acid with more than one ionizable proton lewis acid-base definition - Correct Answers: a model of acid-base behavior in which acids accept and electron pair, and bases donate an electron pair adduct - Correct Answers: the product of a lewis acid-base reaction characterized by the formation of a new covalent bond acid-base buffer - Correct Answers: a solution that resists changes in pH when a small amount of either strong acid or base is added common-ion effect - Correct Answers: the shift in the position of an ionic equilibrium away from the an ion involved in the process that is cause by the addition or presence of that ion buffer capacity - Correct Answers: a measure of the ability of a bugger to resist a change in pH; related to the total concentrations and relative proportions of buffer components buffer range - Correct Answers: the pH range over which a buffer acts effectively acid-base titration curve - Correct Answers: a plot of the pH of a solution of acid (or base) vs. the volume of base (or acid) added to the solution equivalence point - Correct Answers: the point in a titration when the number of moles of the added species is stoichiometrically equivalent to the original number of moles of the other species end point - Correct Answers: the point at which the indicator changes spontaneous change - Correct Answers: a change that occurs by itself, that is, without an ongoing input of energy microstate - Correct Answers: an instantaneous, quantized state of a system of particles throughout which the total energy of the system is dispersed entropy (S) - Correct Answers: a thermodynamic quantity related to the number of ways the energy of a system can be dispersed through the motions of its particles second law of thermodynamics - Correct Answers: a law stating that a process occurs spontaneously in the direction that increases the entropy of the universe third law of thermodynamics - Correct Answers: a law stating that the entropy of perfect crystal solid is zero at 0K standard molar entropy - Correct Answers: the entropy of 1 mol of a substance in its standard stae free energy - Correct Answers: a thermodynamic quantity that is the difference between the enthalpy and the product of the absolute temperature and the entrop electrochemistry - Correct Answers: the study of the relationship between chemical change and electrical work electrochemical cell - Correct Answers: a system that incorporates a redox reaction to produce or use electrical energy half-reaction method - Correct Answers: a method of balancing redox reactions by treating the oxidation and reduction half-reactions separately voltaic (galvanic) cell - Correct Answers: an electrochemical cell that uses spontaneous redox reactions to generate electrical energy electrolytic cell - Correct Answers: an electrochemical system that used electrical energy to drive a non-spontaneous chemical change (G0) electrode - Correct Answers: the part of the electrochemical cell that conducts the electricity between the cell and the surroundings anode - Correct Answers: the electrode at which oxidation occurs in an electrochemical cell. electrons are given up by the reducing agent and leave the cell at the anode cathode - Correct Answers: the electrode at which reduction occurs in an electrochemical cell. electrons enter the cell and are acquired by the oxidizing agent at the cathode half-cell - Correct Answers: a portion of an electrochemical cell in which a half-reaction takes place salt-bridge - Correct Answers: an inverted U tube containing a solution of a non reacting electrolyte that connects the compartments of a voltaic cell and maintains neutrality by allowing ions to flow between the two compartments cell potential (Ecell) - Correct Answers: the potential difference between electrodes of an electrochemical cell when no current flows volt - Correct Answers: the SI unit of electric potential coulomb - Correct Answers: SI unit for electrical charge