# PChem

 Which of the following properties is extensive? a. densityb. temperaturec. pressured. particle numbere. none of the above
 d. particle number *Intensive properties are not dependent on the amount of matter present while extensive properties are dependent on the amount of matter present.
 The internal energy U of an ideal gas is made up a. only o fpotential energy due to interaction between the particlesb. both potential and kinetic energyc. neither of potential nor of kinetic energyd. only of kinetic energy of the gas molecule
 d. only of kinetic energy of the gas molecule
 Suppose we increase the temperature of a gas by a factor 2 (T2=2*T1). What is the relationship between the average speed of molecules? a. v2=4*v1b. v2=v1c. v2=2*v1d. v2=sqrt(2)*v1e. v2=(1/2)*v1f. none of the above
 d. v2=sqrt(2)*v1 v_avg=(3*kb*T)/m
 Suppose we increase the temperature of a gas by a factor 2 (T2=2*T1). What is the relationship between the kinetic energies? a. E2=4*E1b. E2=E1c. E2=2*E1d. E2=sqrt(2)*E1e. E2=(1/2)*E1f. none of the above
 e. E2=(1/2)*E1 E=(3/2)*kb*T
 If O2 and H2 behave as an ideal gas, and are at the same temperature, the average kinetic energy a. of H2 is larger than that of O2b. of H2 is smaller than that of O2c. of the molecules in both gases is the same
 c. of the molecules in both gases is the same
 The Maxwell distribution law gives the probability distribution distribution of the speed of gas molecules. When temperature increases a. the distribution curve becomes sharperb. the area under the distribution becomes smallerc. the average speed of the molecules decreasesd. the distribution curve becomes flattere. none of the above
 d. the distribution curve becomes flatter
 For an ideal gas, the molar heat capacity at constant pressure is a. larger than the molar heat capacity at constant volumeb. smaller than the molar heat capacity at constant volumec. equal to the molar heat capacity at constant volumed. the negative of the molar heat capacity at constant volumee. not related to the molar heat capacity at constant volumef. none of the above
 a. larger than the molar heat capacity at constant volume R=Cp-Cv
 Atmospheric pressure a. decreases exponentially with altitudeb. increases exponentially with altitudec. does not depend on temperatured. none of the above
 a. decreases exponentially with altitude P=P0*exp((m*g)/(R*T))
 In the van der Wall’s equation, the correction for volume accounts for a. interactions between gas moleculesb. finite size of gas moleculesc. none of the above
 b. finite size of gas molecules *VDW EOS takes into account molecular size and molecular interaction forces
 For an ideal gas, the compression coefficient is a. z=1b. z=0c. z=-1d. none of the above
 a. z=1
 The first law of thermodynamic states that a. the energy of an isolated system increases as it approaches equilibriumb. the energy of an isolated system decreases as it approaches equilibriumc. The energy does not change with time in an isolated systemd. none of the above
 c. The energy does not change with time in an isolated system (dU/dt)=0
 For a system at constant pressure, heat added to or subtracted from a system is equal to a. the change deltaU in internal energyb. the change deltaH in enthalpyc. the change in deltaS in entropyd. none of the above
 b. the change deltaH in enthalpy
 During reversible isothermal expansion of an ideal gas a. deltaU=0 and deltaH>0b. deltaU=0 and delta=0c. deltaU=0 and deltaH<0d. deltaU<0 and deltaH=0e. deltaU>0 and deltaH=0f. none of the above
 b. deltaU=0 and delta=0
 Which of the following is correct about the Joule-Thomson experiment? a. deltaH=0b. deltaU=0c. W=0d. none of the above
 a. deltaH=0
 For an ideal gas, the Joule-Thomson coefficient is a. mu=(5/3)b. mu=1c. mu=0d. mu=-1e. mu=-(5/3)f. none of the above
 c. mu=0
 If you draw P vs V for an ideal gas, the resulting curve a. does not depend of the processb. is steeper for an adiabatic process than for an isothermal processc. is steeper for an isothermal process than for an adiabatic processd. none of the above
 b. is steeper for an adiabatic process than for an isothermal process
 The second law of thermodynamics states that a. the energy is conserved in an isolated systemb. The entropies of all perfectly crystalline substance is zero at T=0Kc. External work is need to pump heat from a system at low temperature to one at higher temperature
 c. External work is need to pump heat from a system at low temperature to one at higher temperature
 Which of the following statements is true for a Carnot cycle? a. the efficiency of a Carnot cycle changes with timeb. A Carnot-like engine that includes irreversible processes is more efficient than one built only out of reversible processesc. A Carnot engine can be used as a refrigeratord. none of the above
 c. A Carnot engine can be used as a refrigerator
 The entropy change in a Carnot cycle is a. positiveb. negativec. zerod. none of the above
 c. zero
 The efficiency of a Carnot engine depends only on a. the type of gasb. the ratio of temperatures Tc/Th, where Th is the higher temperaturec. none of the above
 b. the ratio of temperatures Tc/Th, where Th is the higher temperature
 For a reversible adiabatic expansion of a real gas, the entropy changes as a. deltaS>0b. deltaS=0c. deltaS<0
 b. deltaS=0
 An isolated system is said to be in equilibrium if a. deltaS>0b. deltaS=0c. deltaS<0
 b. deltaS=0
 Which of the following properties is intensive? a. massb. volumec. densityd. particle numbere. none of the above
 c. density *Intensive properties are not dependent on the amount of matter present while extensive properties are dependent on the amount of matter present.*An extensive property divided by another creates an intensive property.
 Suppose we decrease the temperature of a gas by a factor 2 (T2=T1/2). What is the relationship between the kinetic energies? a. E2=4*E1b. E2=E1c. E2=2*E1d. E2=E1/sqrt(2)e. E2=(1/2)*E1f. none of the above
 e. E2=(1/2)*E1 E=(3/2)*kb*T
 Let Pw be the pressure resulting from a 2m column of water and Ph be the pressure resulting from a 2m column of mercury. Which statement is true?a. Pw=Phb. PwPhf. none of the above
 b. Pw
 The first law of thermodynamics states that a. the energy of an isolated system increases as it approaches equilibriumb. the energy of an isolated system is conservedc. the energy of an isolated system decreases as it approaches equilibriumd. the entropy of all perfectly crystalline substances is zero at T=0Ke. external work is needed to pump heat from a system at low temperature to one at a higher temperature
 b. the energy of an isolated system is conserved
 Which of the following statements is true for a Carnot cycle? a. the efficiency of a Carnot cycle depends on the ratio of temperatures Tc/Th, where Th is the higher temperatureb. Not all Carnot engines have the same efficiencyc. A Carnot engine that includes irreversible processes is more efficient than one built only out of reversible processesd. a Carnot engine cannot be used as a refrigeratore. none of the above
 a. the efficiency of a Carnot cycle depends on the ratio of temperatures Tc/Th, where Th is the higher temperature *All Carnot engines have the same efficiency*A Carnot engine can be used as a refrigerator
 Under constant temperature and volume conditions, a system is said to be equilibrium when a. deltaG=0b. deltaA=0c. deltaS=0d. deltaU=0e. deltaH=0f. none of the above
 b. deltaA=0 *deltaG=0 at constant volume and pressure
 How many phases has the following system: CaCO3(s) <-->CaO(s)+CO2(g)? a. 1b. 2c. 3d. none of the above
 c. 3
 How many different phases can at most co-exist in a two component system? a. 1b. 2c. 3d. 4e. 5f. none of the above
 d. 4 *f=c-p+2, where f=0, c=2
 Which statement is true for an ideal solution mixture of two components A and B? a. it forms an azeotropic mixtureb. the liquid curve in the temperature-composition phase diagram is a straight linec. the vapor curve in the temperature-composition phase diagram is a straight lined. the vapor curve in the pressure-composition phase diagram is a straight linee. Raoult’s Law appliesf. none of the above
 e. Raoult’s Law applies
 The following reaction describes dissociation of chlorine into atoms: Cl2<-->2*Cl. If the volume is decreased by half, the degree of dissociation a. increasesb. decreasesc. depending on temperature may or may not changed. will oscillatee. none of the above
 b. decreases *kc=[Cl]^2/[Cl2]=(nCl^2/V^2)/(nCl2/V)=(nCl^2/nCl2)*(1/V)
 An ideal solution of xa mole fraction of A and xb mole fraction of B, with vapor pressures Pa* for pure component A and Pb* for pure component B, has a vapor pressure P given by a. P=Pa*-Pb*b. P=Pa*+Pb*c. P=(xa)(Pa*)-(xb)(Pb*)d. P=(xa)(Pa*)+(xb)(Pb*)e. P=(Pa*)(Pb*)
 d. P=(xa)(Pa*)+(xb)(Pb*)
 Assume two chemical reactions A+B<-->X+Y and X<-->Z, characterized by equilibrium constants k1 and k2, that are coupled leading to a resulting reaction A+B<-->Y+Z. The resulting equilibrium constant k3 is given by a. k3=k1+k2b. k3=k1-k2c. k3=k1*k2d. k3=k1^-1+k2^-1e. k3=k1/k2f. none of the above
 c. k3=k1*k2 k=pi(ki)
 For a chemical reaction A+B<-->C we measure an equilibrium constant k^0<1. Under standard conditions, the reaction will proceed spontaneously from a. left to right (A+B–>C)b. right to left (C–>A+B)
 b. right to left (C–>A+B) *Look at the direction of the operator (k^0<1)
 Assume that the enthalpy difference deltaH^0 between products and reactants in a chemical reaction is independent of temperature, and deltaH^0<0. How does an equilibrium constant kp^0 (describing the same reaction change if the temperature is increased? a. kp^0 increasesb. kp^0 decreasesc. kp^0 does not change
 b. kp^0 decreases *d(ln(kp^0))=-deltaH^0/R*(dT/T^2)*Temperature and kp^0 are inversely related
 In which type of reaction is the half-life independent on the concentration? a. 0th orderb. 1st orderc. 2nd orderd. none of the above
 b. 1st order
 Assume a reaction A<-->B, characterized by rate constants kab and kba. These two rate constants are related to the equilibrium constant kc by a. kc=kab+kbab. kc=kab-kbac. kc=kab*kbad. kc=kab/kbae. kc=kba/kabf. none of the above
 d. kc=kab/kba *keq=kforward/kbackward
 Assume a reaction A+B<-->Z. Empirically, wefind the fllowing relation between the rate of formation of a product Z and the concentrations of two reactants A and B: vz=kz[A]^0.5[B]^1.5. What would be the order of the reaction? a. 0.5b. 1c. 1.5d. 2e. 2.5f. none of the above
 d. 2 *Add the exponents to determine overall order
 Assume two 1st order reactions characterized by rate constants k1 and k2, with k2=4*k1. The half-life of reaction 1 is a. double that of reaction 2b. four times that of reaction 2c. half that of reaction 2d. a quarter of that of reaction 2e. none of the above
 b. four times that of reaction 2
 If a reaction has a rate constant of k=6.3e-5 L/(mol*s), the reaction is a. 0th orderb. 1st orderc. 2nd orderd. cannot be determined based on the given informatione. none of the above
 c. 2nd order
 How does the concentration [A] of a reactant A change with time in a 1st order reaction? a. decreases linearlyb. decreases logarithmicallyc. decreases exponentiallyd. increases exponentiallye. increases logarithmicallyf. increases linearlyg. none of the above
 c. decreases exponentially
 In the consecutive reaction A–k1–>X–k2–>Z, where X is an intermediate, the steady state condition applies when a. k1 is much smaller than k2b. k2 is much smaller than k1c. none of the above
 a. k1 is much smaller than k2
 In the consecutive reaction A–k1–>X–k2–>Z, where X is an intermediate, which quantity is zero at steady state? a. [X]b. [Z]c. [A]d. d[Z]/dte. d[A]/dtf. d[X]/dtg. none of the above
 f. d[X]/dt
 In an enzyme-catalyzed reaction, if the concentration of substrate is very large, the reaction is a. 3rd order in substrateb. 2nd order in substratec. 1st order in substrated. 0th order in substratee. none of the above
 d. 0th order in substrate
 For an equilibrium system at constant pressure and temperature, the Gibbs energy is a. deltaG=0b. deltaG<0c. deltaG>0
 a. deltaG=0
 Le Chatelier’s principle implies that a. the equilibrium cannot be shifted by changing pressure or concentrationb. volume or pressure changes can shift the equilibriumc. And equilibrium constant can change to counteract any disturbance to a system at equilibrium
 b. volume or pressure changes can shift the equilibrium
 When equilibrium is reached, the total Gibbs energy of the reactants and products a. is the sameb. differs, but has the same signc. differs in both value and signd. is both zeroe. adds up to zerof. none of the above
 a. is the same
 Assume two chemical reactions A+B<-->X+Y and X<-->Z, characterized by Gibbs energy differences (between products and reactants) deltaG1 and deltaG2. When coiuple the two reactions, one finds for the resulting reaction A+B<-->Y+Z a. deltaG=(deltaG1)(deltaG2)b. deltaG=(deltaG1)/(deltaG2)c. deltaG=deltaG1+deltaG2d. deltaG=deltaG1-deltaG2e. none of the above
 c. deltaG=deltaG1+deltaG2 deltaG=sum(deltaGi)
 The following reaction describes dissociation of chlorine into atoms: Cl2<-->2*Cl. If the volume is increased, the degree of dissociation a. decreasesb. increasesc. does not change
 b. increases *kc=[Cl]^2/[Cl2]=(nCl^2/V^2)/(nCl2/V)=(nCl^2/nCl2)*(1/V)*kc and volume are directly related
 For a chemical reaction A+B<-->C we measure an equilibrium constant k^0>1. Under standard conditions, the reaction will proceed spontaneously from a. left to right (A+B–>C)b. right to left (C–>A+B)
 a. left to right (A+B–>C)
 Assume a chemical reaction A+B<-->C in equilibrium. When we remove a certain about of B, the equilibrium a. shifts to the leftb. shifts to the rightc. stays unchanged
 a. shifts to the left
 Another way to shift the equilibrium is to couple the reaction of interest with a second one. To make an unfavorable reaction possible, what is the requirement for the second reaction?a. deltaG2^0deltaG1^0c. deltaG2^0+deltaG1^0>0d. deltaG2^0+deltaG1^0<0e. none of the above
 d. deltaG2^0+deltaG1^0<0 *deltaGtot must be negative to be spontaneous or favorable
 In a van’t Hoff plot, ln(Kp^0) is plotted as a function of the inverse temperature 1/T. If deltaH^0 is independent of temperature one obtains a straight line. From slope and intercept one finds a. slope: -deltaS^0/Rb. intercept: -deltaS^0/Rc. intercept: -deltaH^0/Rd. intercept: -deltaH^0/R-deltaS^0/Re. slope: -deltaH^0/R-deltaS^0/Rf. none of the above
 f. none of the above ln(kp^0)=-deltaH^0/R+deltaS^0/R
 Which of the following is true for an equilibrium constant kc^0? a. its value does not depend on temperature b. its value does not depend on the units of concentrationc. its value depends on the stoichiometric equation used in its definition
 c. its value depends on the stoichiometric equation used in its definition
 Assume that the enthalpy difference deltaH^0 between products and reactants in a chemical reaction is independent of temperature, and deltaH^0<0. How does an equilibrium constant kp^0 (describing the same reaction) change if the temperature is decreased? a. kp^0 decreasesb. kp^0 increasesc. kp^0 does not change
 b. kp^0 increases *ln(kp^0) is proportional to (-deltaH^0/R)*(1/T)
 How many different phases can at most co-exist in a three component system? a. 1b. 2c. 3d. 4e. 5f. none of the above
 e. 5 *f=c-p+2, where f=0 and c=3
 Determine the number of degrees of freedom for ice in a solution of water and alcohol. a. 0b. 1c. 2d. 3e. none of the above
 c. 2 *f=c-p+2, where c=2 (water, alcohol) and p=2 (liquid, solid)
 Consider an ideal solution mixture of components A and B in equilibrium with vapor. A is more volatile than B. Compared to the liquid, the vapor contains a. less of Ab. less of Bc. equal amounts of A and Bd. none of the above
 b. less of B *More volatile will vaporize first, therefore there will be more A in the vapor state than in the liquid state relative to B
 At triple point, what is the thermodynamic quantity that is the same for all three phases? a. internal energy Ub. entropy Sc. chemical potential mud. enthalpy He. none of the above
 c. chemical potential mu
 Which of the following quantities has a discontinuity in a 1st order phase transition? a. Gibbs energy Gb. entropy Sc. enthalpy Hd. none of the above
 b. entropy S
 Consider water above the critical temperature Tc. Which of the following statements is correct for this system? a. only one phase existsb. the number of possible phase depends on the pressure in the systemc. there will be a liquid vapor transitiond. none of the above
 a. only one phase exists
 How many independent components are present in the following system: CO(g)+3*H2(g)<-->CH4(g)+H2O(g)? a. 1b. 2c. 3d. 4e. none of the above
 c. 3 4-1=3
 Which of the following is correct for a completely immiscible two component solution? a. Raoult’s law appliesb. its bioling point is that of the more volatile componentc. it has a higher boiling point than the individual componentsd. it has a lower boiling point than the individual componentse. none of the above
 d. it has a lower boiling point than the individual components *Each component supplies much more pressure so it boils faster (lower temperature)*a. for ideal and miscible*c. there’s more pressure so Tbp will be lower
 Consider an ideal solution mixture of components A and B in equilibrium with vapor. B is more volatile than A. Compared to the liquid, the vapor contains a. less of Ab. less of Bc. equal amounts of A and Bd. none of the above
 a. less of A
 Which of the following is true during steam distillation? a. the composition of the vapor phase depends on that of the liquid phaseb. the composition of the vapor phase does not changec. the composition of the vapor and liquid phases is always identicald. none of the above
 b. the composition of the vapor phase does not change *a. true for miscible cases*c. true at azeotropic point
 Which is true for an azeotropic mixture of two liquids? a. the composition of vapor and liquid phases are not identicalb. it corresponds to an ideal solution made out of 50% of each liquidc. it cannot be further purified by distillationd. none of the above
 c. it cannot be further purified by distillation
 Which of the following has a discontinuity in a 1st order phase transition? a. Gibbs energy Gb. volume Vc. enthalpy Hd. none of the above
 b. volume V
 Assume a chemical reaction A+B<-->C. When we add a certain amount of B, the equilibrium a. shifts to the leftb. shifts to the rightc. stays unchanged
 b. shifts to the right
 For the chemical reaction, 2H–>H2 at constant volume, the entropy change is a. deltaS<0b. deltaS>0c. deltaS=0
 a. deltaS<0
 Is the change in Helmholtz energy for the above reaction at room temperature a. deltaA=0b. deltaA<0c. deltaA>0
 c. deltaA>0
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