Download Chemistry Exam: April 30, 2008 - Questions and Answers - Prof. Eric Glendening and more Exams Chemistry in PDF only on Docsity!
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Chem 106 April 30, 2008
Final Exam
- (3 pts) Circle the molecules that have a permanent dipole moment.
CH 3 F CO 2 OCS CH 4 NH 3
- (4 pts) Circle the aqueous solution that has the highest boiling point; cross
out the solution that has the highest freezing point.
0.05 m NaF 0.15 m NH 3 0.10 m MgCl 2 0.05 m CH 3 OH
- (5 pts) How much heat is required to convert 36.0 g of ice (FM=18.02) at 0.°C
to steam at 100.°C? ( s =4.184 J/g°C; ∆ H vap=40.79 kJ/mol; ∆ H fus =6.01 kJ/mol)
q = ___________
- (5 pts) Determine the heat of vaporization (in kJ/mol) of a liquid. The
normal boiling point of the liquid is 358 K, and its vapor pressure is 104 torr
at 298 K.
∆ H = ___________
(3 pts) Draw a Cl
ion interacting with a water molecule. Name the
intermolecular force.
- (3 pts) The dissolution of PbCl 2 is endothermic. Will the following changes
increase, decrease, or have no effect on the solubility of PbCl 2?
PbCl 2 ( s ) Pb
2+ ( aq ) + 2 Cl
_________ NaCl is added to the solution.
_________ A catalyst is added to the solution.
_________ The temperature is decreased.
- (6 pts) Thermal decomposition of phosphine (PH 3 ) into phosphorus and
molecular hydrogen [4 PH 3 ( g ) P 4 ( g ) + 6 H 2 ( g )] is a first‐order process.
The half‐life of the reaction is 63.1 s at 450°C. Calculate the time required
for 90 percent of the phosphine to decompose.
t = ___________
- (6 pts) State whether the following are characteristics of zeroth-, first-, or
second-order kinetics for the reaction A → products. If there is insufficient
information to determine the order of reaction, indicate so.
__________ The reaction rate is independent of [A].
__________ Tripling [A] triples the reaction rate.
__________ k has the units L mol
__________ The reaction rate increases with temperature.
__________ A plot of ln[A] vs time is linear.
__________ U-238 undergoes radioactive decay.
- (2 pts) Circle any reaction intermediates in the following mechanism.
- O 3 + Cl O 2 + ClO
- O 3 + ClO 2 O 2 + Cl
- (2 pts) Q c = 0.015 and K c = 0.010 for a reaction. The reaction
(a) is at equilibrium.
(b) will proceed toward reactants.
(c) will proceed toward products.
ln K = –59000(1/T) + 13
0.0007 0.0009 0.0011 0. 1 / T (1/K)
ln K
(5 pts) The solubility of Ag 2 SO 4 is 4.4×
mol/L. What is K sp for Ag 2 SO 4?
K sp = ___________
(5 pts) The solubility product of AgCl is 1.6×
at 298 K. What is ∆ G
0 ?
AgCl( s ) Ag
( aq ) + Cl
∆ G
0 = ___________
- (6 pts) The temperature dependence of K was
determined for the dissociation of molecular
oxygen [O 2 ( g ) 2 O( g )]. The following plot
was prepared, and the equation for the best
linear fit of the data is shown.
What are the values of ∆ H
0 and ∆ S
0 for the
dissociation of O 2?
∆ H
0 = ___________
∆ S
0 = ___________
- (2 pts) The values of ∆ H
0 and ∆ S
0 for a reaction are 122 kJ/mol and 130
J/mol K, respectively. The reaction is
(a) spontaneous at all temperatures
(b) spontaneous only at low temperatures
(c) spontaneous only at high temperatures
(d) nonspontaneous at all temperatures.
- (2 pts) What is the value of ∆ G at equilibrium for AgCl Ag
∆ G = ___________
- (6 pts) Balance the following redox reaction in acidic solution.
MnO 4
2+
- (4 pts) Write the balanced equation for the following cell:
Mn( s ) | Mn
2+ ( aq ) || Cd
2+ ( aq ) | Cd( s )
What is the half‐reaction at the cathode?
What is the oxidizing agent?
- (10 pts) A voltaic cell consists of an Mn/Mn
2+ half‐cell and a Pb/Pb
2+ half‐
cell. Calculate [Pb
2+ ] when [Mn
2+ ] is 1.3 M and E cell is 0.95 V at 25°C. The
following are the standard reductions potentials for the half‐cells.
Pb
2+
0 = –0.13 V
Mn
2+
0 = –1.18 V
[Pb
2+ ] = ___________
