AP Chemistry Chapter 19 Thermodynamics Practice TestMultiple Choice Identify the choice that best completes the statement or answers the question. ____ 1. ∆G refers to the free-energy change associated with which of the following? a. the formation of 1 mol of a compound from its constituent elements. b. the decomposition of 1 mole of a compound into its constituent elements. c. the freezing of 1 mol of a substance. d. the melting of 1 mol of a substance. e. all of the above. ____ 2. Under what conditions can we absolutely say a system is at equilibrium at constant pressure and temperature? a. ∆H ! d. ∆G " ! b. ∆H " ! e. ∆S " ! c. ∆G ! ____ #. $hich of the following substances would you e%pect to have the highest entropy at 1 atm of pressure? a. & '(s)(1 mol) d. !.* mol of ethanol in !.* mol of & '(l) b. & '(l)(1 mol) e. a gaseous solution of !.* mol of & '(g) and !.* mol of +& (g) c. & '(g)(1 mol) ____ ,. -or any isolated spontaneous process that is endothermic. which of the following conditions are true/ (1) ∆G 0 ! (2) ∆G " ! (#) ∆S 0 ! (,)∆S " ! (*) ∆S 0 ! (1) ∆S " ! a. (1. (#) and (,) d. (1). (,) and (1) b. (2). (,) and (1) e. (2). (,) and (1) c. (1). (,) and (*) ____ *. -or which of the following changes would you e%pect ∆S to be less than zero? a. & '(l) → & '(g) d. +' (s) → +' (g) b. +'(g) 2 3' (g) → +' (g) e. 2 4g+l(s) → 2 4g(s) 2 +l (g) c. 2 5' (g) → 2 5' (g) 2 ' (g) ____ 1. $hen 67' dissolves in water at room temperature. ∆H is positive for the dissolution process. 8iven this information. what can you conclude? a. ∆G " ! for the dissolution process. d. ∆S " ! for the dissolution process. b. ∆G ! for the dissolution process. e. ∆S 0 ! for the dissolution process. c. 9he dissolving of salts in water is always a spontaneous process. ____ :. $hich of the following is true for the sublimation of solid +' at room temperature and pressure? a. ∆H and ∆S are positive. d. ∆G becomes more positive as temperature increases. b. ∆H and ∆S are negative. e. ∆G is positive. c. ∆H is negative and ∆S are positive. ____ ;. $hich of the following can be used to calculate directly the value of an equilibrium constant for a reaction at a given temperature? a. ∆H d. ∆G b. ∆H° e. ∆G° c. ∆S ____ <. +alculate ∆G° for the following reaction at 2*°+ , 7'(g) 2 1 & '(g) → * ' (g) + , 7& (g) given the following ∆G values/ 7'. ;1.:1 =>?mol@ & '. −22;.11 =>?mol@ ' . !.! =>?mol@ 7& . −11.11 =>?mol. a. <*;.2 => d. −1#1;.1; => b. −21,*.1, => e. 1#1;.1; => c. 21,*.1, => ____ 1!. Astimate the normal boiling point for &+l. given the following information/ ∆H 11.1# =>?mol and ∆S ;*.:: >?molB6 a. 1;;C+ d. !.1;< 6 b. 1;; 6 e. 1!!C+ c. !.1;<C+ ____ 11. 9he standard free energy of formation. ∆G . for sodium chloride is the free energy change for which of the following reactions? a. 7a (g) 2 +l (g) → 7a+l(g) d. 7a(s) 2 3+l (g) → 7a+l(s) b. 7a (g) 2 +l (g) → 7a+l(s) e. 2 7a+l(s) → 27a(s) 2 +l (g) c. 2 7a(s) 2 +l (g) → 2 7a+l(s) ____ 12. -or which of these processes is the value of ∆S e%pected to be negative? D. 7a+l is dissolved in water. DD. 5team condenses to liquid water. DDD. Eg+' is decomposed into Eg' and +' . a. D only d. DD and DDD only b. D and DDD only e. D and DD only c. DD only ____ 1#. $hat are the signs of the enthalpy change and entropy change for the melting of ice? & '(s) → & '(l) 9he signs represent ∆H° and ∆S°. respectively. a. 2. 2 d. +. − b. −. − e. !. ! c. −. + ____ 1,. Under which set of conditions does a temperature e%ist at which equilibrium can be established with all reactants and products in standard states? D. ∆S is 2. ∆H is 2 DD. ∆S is −. ∆H is − DDD. ∆S is 2. ∆H is − a. D only d. D and DD only b. DD only e. D and DDD only c. DDD only ____ 1*. $hich of the following substances is e%pected to have the largest standard molar entropy? a. & '(s) d. & ' (l) b. & '(l) e. & ' (g) c. & '(g) ____ 11. Dn which process would ∆G be e%pected to be positive? a. melting ice at −1!°+ and 1.! atm pressure d. sublimation of dry ice at 2*°+ b. water evaporating at 2*°+ into dry air e. a burning campfire c. cooling hot water to room temperature ____ 1:. $hich is not e%pected to have a value of zero? a. ∆H for ' (g) d. ∆H for Fr (l) b. ∆G for 6(g) e. ∆G for '(g) c. S for +a(s) at ! 6 ____ 1;. $hich process is e%othermic and occurs with a decrease in entropy? a. & '(l) → & '(s) d. 2 & '(l) → 2 & (g) 2 ' (g) b. & '(s) → & '(l) e. & '(l) → & '(g) c. & '(s) → & '(g) ____ 1<. Dn order to calculate the entropy change for the following reaction at 2*°+ and one atmosphere. what additional thermodynamic information is needed? +(s. graphite) 2 '2(g) G +'2(g) a. ∆H for +' (g) b. ∆G for +' (g) c. ∆H and ∆G for +' (g) d. S° for +' (g) e. ∆H and ∆G for both +(s. graphite) and ' (g) ____ 2!. -or a certain reaction. ∆H° −1*! =>?mol and ∆S° −*! >?mol ⋅ 6. $hich of the following statements is true about the reaction? a. Dt is spontaneous at high temperatures only. b. Dt is spontaneous at low temperatures only. c. Dt is spontaneous at all temperatures. d. Dt is nonspontaneous at all temperatures. e. 9here is no temperature at which the reaction will reach equilibrium. Problem 21. +alculate the p& of water at ,!C+ given the following information for the equilibrium at 2*C+/ & '(l) ⇔ & (aq) 2 '& (aq) ∆G (=>?mol) −2#:.2 ! −1*:.# ∆H (=>?mol) −2;*.; ! −2#!.! (&int/ Hetermine ∆G° and K at ,!°+ to solve for p&.)