GEN CHEM II (All 4 Exam Crammed Into One)

C

Consider an electrochemical cell with a zinc electrode immersed in 1.0M Zn2+ and a silver electrode immersed in 1.0M Ag+. Calculate E0 for this cell A). -0.04V B).0.04V C). 1.56V D).-1.56V E). None of these

E

Consider the following reaction at constant pressure. Which response is true? 2N2 (g) + O2 (g) --> 2N2O(g) A). the amount of work depends on the temperature B). Work is done by the system as it occurs C). The amount of work depends on the pressure D). no work is done as the reaction occurs E). work is done on the system as it occurs

D

Consider the reaction 2NO2 <----> N2O4. A reaction is initiated at 100C with 2.35 moles NO2 in a 3.0 L reactor (no N2O4 present). If the equilibrium concentration of N2O4 is 0.25 M, what is the value of Kc at 100C? A). 0.25 B). 0.31 C). 6.7 D). 3.2 E). 0.15

A

Determine DeltaG0 for a cell that utilizes the following reaction: Cl2 (g) + 2Br- (aq) --> 2Cl- (aq) + Br2 (l) A). -54.4 kJ B). -23.9kJ C). -235kJ D). 27.2 kJ E). -470 kJ

E

Estimate the heat of reaction at 298K for the reaction shown, given the average bond energies below. H2C=CH2 (g) + H2 (g) --> CH3CH3 (g) Bond (Bond Energy) C-C (350 kJ) C=C (728 kJ) C-H (410 kJ) H-H (436 kJ)

A

For a particular process, q=20 kJ and w=15kJ. Which of the following statements is TRUE? A). heat flows form the surroundings to the system B). the system does work on the surroundings C). Delta E=5kJ D). heat flows from the system to the surroundings E). Delta E= -35kJ

B

For a reversible reaction with a one-step mechanism A <---> B, the rate of the forward reaction is rate(f)=3.2E-6 [A] and the rate of the reverse reaction is rate(r)=4.6E-4 [B]. What is the value of Kc for this reaction? A). 1.5E-9 B). 7.0E-3 C). 7.0E9 D). 2.5E-11 E). 1.4E2

C

For the reaction 3O2 <---> 2 O3, the value of the equilibrium constant is 0.0187 at a particular temperature. If the equilibrium concentration of [O2] is 0.75 M, what is the equilibrium concentration of O3? A). 0.014 M B). 0.22 M C). 0.089 M D). 0.0079 M E). 0.75 M

A

How many grams of BaCO3 will dissolve in 853 mL of 0.15 M BaCl2? Ksp(BaCO3)=8.1E-9 A). 9.1E-6 B). 4.6E-8 C). 8.1E-9 D). 5.5E-8 E). 1.1E-5

C

How many seconds would it take to deposit 18.2 g of Ag (atomic mass= 107.87) from a solution of AgNO3 using a current of 10.00 amp? A). 8.14E2 s B). 4.88E3 s C). 1.63E3 s D). 3.26E3 s E). 5.43E2 s

E

How much heat is released by the "roasting" of 48.7 g of ZnS at constant pressure, if the Delta H of the reaction (shown below) is -881 kJ/mol rxn 2ZnS (s) + 3O2 (g) --> 2ZnO (s) + 2SO2 (g) A). 110 kJ B). 881 kJ C). 440 kJ D). 293 kJ E). 220 kJ

B

How much heat is required to raise the temperature of a 5.75 g sample of iron (specific heat=0.450 J/G C) from 25.0 C to 79.8 C? A). 2.54 J B). 142 J C). 848 J D). 700 J E). 315 J

A

If a constant current of 5.0 amperes is passed through a cell containing Cr3+ for 1.0 hour, how many grams of Cr will plate out onto the cathode? (The atomic mass of Cr is 51.996) A). 3.2g B). 9.7g C). 29g D). 9.0E-4g E). 6.2E-2g

C

If the complete burning (see reaction below) of 75g of octane (C8H18) releases 3600 kJ, what is the enthalpy change of the reaction? C8H18 + 25/2 O2 --> 8CO2 + 9H2O A). 5500 kJ B). 3600 kJ C). -5500 kJ D). -3600 kJ E). 7200 kJ

D

Magnesium hydroxide is a slightly soluble substance. If the pH of a saturated solution of Mg(OH)2 is 10.49 at 25C, calculate Ksp for Mg(OH)2 A). 4.2E-15 B). 4.4E-14 C). 6.0E-10 D). 1.5E-11 E). 8.8E-16

E

A molecule of ethyl alcohol is converted to acetaldehyde in ones according to the following equation: CH3CH2OH + [O] --> CH3CH=O + H2O If the concentration of alcohol is 0.015 mol/L and the rate constant = 6.4E-5, what is the concentration of alcohol after 3.5 hours? A). 4.3E-3 B). 9.6E7 C). 0.0032 D). 0.15 E). 0.0016

C

A negative change in entropy represents: A). an increase in thermal energy B). a process that is always spontaneous C). a decrease in dispersal of matter or energy D). absorption of thermal energy E). a process that cannot occur spontaneously

C

A solution that is 0.20 M in NH3 is also 0.30 M in NH4Cl. What is the [OH-] in this solution? A). 6.4E-4 B). 4.5E-6 C). 1.2E-5 D). 2.4E-7 E). 7.4E-5

E

Calculate Delta G for the reaction below at 398K. The entropy change for the reaction is -287.5 J/molK. 3NO2 (g) + H2O (l) --> 2HNO3 (aq) + NO(g) + 136.8 kJ A). 22.4 kJ B). -68.4 kJ C). -51.2 kJ D). 51.2 kJ E) 22.4 kJ

D

Calculate Delta H at 25 C for the reaction below: 3N2O4 (11.1 kJ/mol) + 2H2O (-285.8 kJ/mol) --> 4HNO3 (-207.4 kJ/mol) + 2NO (91.3 kJ/mol) A). -257.1 kJ B). +879.0 kJ C). -879.0 kJ D). -108.7 kJ E). +257.1 kJ

D

Calculate the hydrolysis constant for the ammonium ion, NH4+. A). 1.0E-7 B). 2.5E-5 C). 4.0E-10 D). 5.6E-10 E). 5.5E-4

A

Calculate the pH in a 0.025 M Ca(OH)2 solution. A). 12.70 B). 1.30 C). 1.60 D). no way to calculate without Kb E). 4.20

C

Calculate the pH of 0.050 M acid solution, if Ka of the acid is 6.3E-5 A). 2.10 B). 1.45 C). 2.75 D). 5.50 E). 4.20

B

Calculate the pH of 0.15 M Co(NO3)2. For [Co(OH2)6]2+, Ka=5.0E-10 A). 4.74 B). 5.06 C). 5.28 D). 4.88 E). 4.52

D

Calculate the solubility product constant for aluminum hydroxide. Its molar solubility is 2.9E-9 mole per liter at 25C A). 7.1E-35 B). 9.8E-26 C). 2.1E-34 D). 1.9E-33 E). 4.9E-26

E

Calculate the standard cell potential for the cell, Pb|Pb2+ (1M) || Ag+ (1M)|Ag A). +0.673V B). -0.673V C). -0.925V D). 0.00V E). +0.925V

E

The following system is at equilibrium with [N2O4]= 0.55 M and [NO2]= 0.25 M. If an additional 0.10 M NO2 is added to the reaction mixture with no change in volume, what will be the new equilibrium concentration of N2O4? N2O4 (g) <----> 2NO2 (g) A). 0.50 M B). 0.45 M C). 0.70 M D). 0.26 M E). 0.62 M

E

The half-life for the reactant A in the first order reaction A-->B is 36.2 seconds. What is the rate constant for this reaction at the same temperature? A). 52.2 s B). 0.0276 s C). 18.1 s D). 0.00832 s E). 0.0191 s

B

The reaction: SF4 --> SF2 + F2 has the following rate law: rate= 0.011 L/mols [SF4]2. How many minutes will it take for the concentration of SF4 to be reduced from 2.5 M to 0.25 M? A). 0.04 min B). 5.5 min C). 327 min D). 22.7 min E). 0.025 min

B

The specific rate constant, k, for a reaction is 2.64E-2 at 25C, and the activation energy is 74.0 kJ/mol. Calculate k at 50C. (The universal gas constant=8.314 J) ( ln(k2/k1) = (Ea/R) ((1/T1) - (1/T2)) A). 0.832 B). 0.266 C). 0.0265 D). 71.9 E). 1.08

B

What is the [H3O+] in 0.40 M CsCN solution? A). 4.8E-3 B). 3.2E-12 C). 3.3E-11 D). 1.4E-2 E). 6.4E-10

A

What is the entropy change of the reaction below at 298K and 1 atm pressure? N2 (191.5 J) + 3H2 (130.6 J) --> 2NH3 (192.3 J) A). -198.7 J B). 384.7 J C). -129.7 J D). 303.2 J E). 76.32 J

A

What is the value of Kc for the reaction 2A (g) + 3B (g) <---> 2C (g) + D (g) if at equilibrium [A]=0.60 M, [B]=0.30 M, [C]= 0.10M, [D]= 0.50 M? A). 0.51 B). 0.15 C). 0.088 D). 2.4 E). 1.9

D

What is the value of the standard internal energy change of the following reaction at constant temperature and pressure? 2NO(g) + O2 (g) --> NO2 (g) + 131 kJ (DeltaE=DeltaH-DeltanRT; R=8.314 J/molK) A). 278 kJ B). 435 kJ C). -435 kJ D). -126 kJ E). 126 kJ

E

Which of the following statements regarding spontaneous changes is FALSE? A). ice melting at 25 C is spontaneous primarily due to the increase in molecular disorder (dispersal of matter) B). Spontaneous changes occur at a given state without any outside influence C). Spontaneity is favored when the dispersal of matter is increased D). Spontaneity is favored when heat is released E). all exothermic reactions are spontaneous

C

Which solution wold have the LOWEST [OH-]? A). 0.10 M NaCl B). 0.50 M NH3 C). 0.50 M Hal D). Pure water E). 0.10 M NaOH