Transcript G - Senger Science

Advanced Chemistry
Semester 2
2016
1-27-16 Bell Ringer
Today you are beginning your write up for your STEAM Presentation…
Your time can be used to:
A) Research your potential topic
B) Begin writing up your lab introduction using our Lab write up format
from MT Tech
C) Register on the STEAM website for your presentation April 2 (Sat 102:00). If you do not attend, you will be presenting to the class. Your oral
grade will be based off your STEAM score. If in class, I will be your scorer.
D) First person to show me where on our class webpage the handout for
your lab write up is gets 5% etc added to their last exam
1-27-16 Exit
We will be forming 2 lines…Stand across from your class BFF. Be prepared to
share your research topic choice(s). When you share your choice, your
friend will tell you a comment that will help you with your project.
Acceptable comment examples: “What one variable are you isolating” or
“Where will you get your materials” or any comment about the errors they
might encounter and need to anticipate
Unacceptable comment examples: “Cool idea Bro” or “I like your face” or
anything not constructive in helping them with their topic
1-28-16 Bell Ringer
Final Day of Research!!!
Please type your Heading and Introduction if you have not started this
component of your project. When complete, call Senger over to verify
that you have these 2 portions started for points today.
1-28-16 Exit
On a sheet of paper, please list anything you might need from Senger
to complete this project.
Examples: a day to type, any materials, a day to perform experiments
etc.
1-29-16 Bell Ringer
In a mixture of the major components of
natural gas: CH4, C2H6, C3H8, and C4H10,
which gas effuses the slowest and which
the fastest?
1-29-16 Exit
How much faster does F2 effuse than Cl2
at 25°C?
2-1-16 Bell Ringer
The pressure on a sample of an ideal gas
is increased from 715 mmHg to 3.55 atm
at constant temperature. If the initial
volume of the gas is 485 mL, what is the
final volume of the gas?
2-1-16 Exit
At what temperature will 1.00 mol of an
ideal gas in a 1.00 L container exert a
pressure of 1.00 atm?
2-2-16 Bell Ringer
A 100.0 mL flask contains 0.193 g of a
volatile oxide of nitrogen. The pressure in
the flask is 760 mmHg at 17°C.
Is the gas NO, NO2, or N2O5?
2-2-16 Exit
Calculate the volume of carbon dioxide at
20°C and 1.00 atm produced from the
complete combustion of 1.00 kg of
methane. Compare your result with the
volume of CO2 produced from the
complete combustion of 1.00 kg of
propane (C3H8).
2-3-16 Bell Ringer
A gas mixture contains 0.70 mol N2, 0.20
mol H2, and 0.10 mol CH4. What is the
mole fraction of H2 in the mixture?
2-3-16 Exit
Ozone reacts completely with NO,
producing NO2 and O2. A 2.50 L vessel is
filled with 0.150 mol NO and 0.150 mol
O3 at 125°C. What is the partial pressure
of each product and the total pressure in
the flask at the end of the reaction?
2-4-16 Bell Ringer
The solubility of O2 in water is 6.5 mg/L
at an atmospheric pressure of 1 atm and
a temperature of 40°C. Calculate the
Henry’s law constant of O2 at 40°C.
2-4-16 Exit
Air is approximately 21% O2 and 78% N2
by mass. Calculate the root-mean-square
speed of each gas at 273 K.
2-5-16 Bell Ringer
Which noble gas is expected to deviate
the most from ideal behavior in a graph
of PV/RT versus P?
2-5-16 Exit
Calculate the pressure exerted by 5.00
mol of CO2 in a 1.00 L vessel at 300 K (a)
assuming the gas behaves ideally and (b)
using the van der Waals equation.
1-8-16 Bell Ringer
Calculate the lattice energy of sodium oxide (Na2O) from the following
data:
Ionization energy of Na(g) = 495 kJ/mol
Electron affinity of O(g) for 2 electrons = 603 kJ/mol
Energy to sublime Na(s) = 109 kJ/mol
Bond energy of O2(g) = 498 kJ/mol
∆Hrxn for 2 Na(s) + 1/2 O2(g) → Na2O(s) = –416 kJ/mol
1-8-16 Exit
Rank the compounds in Figure P11.16 in
order of increasing vapor pressure at 298 K.
2-9-16 Bell Ringer
Why does the boiling point of a mixture
of volatile hydrocarbons increase over
time during a distillation?
2-9-16 Exit
A bottle is half-filled with a 50:50 (by moles)
mixture of heptane (C7H16) and octane
(C8H18) at 25°C. What is the mole ratio of
heptane vapor to octane vapor in the air
space above the liquid in the bottle? The
vapor pressures of heptane and octane at
25°C are 31 torr and 11 torr, respectively.
2-10-16 Bell Ringer
A solution contains 4.5 mol of water, 0.3 mol of sucrose
(C12H22O11), and 0.2 mol of glucose. Sucrose and glucose are
nonvolatile.
What is the mole fraction of water in the solution?
What is the vapor pressure of the solution at 35°C, given
that the vapor pressure of pure water at 35°C is 42.2 torr?
2-10-16 Exit
How many moles of solute are there in the following
solutions?
a. 0.150 m glucose solution made by dissolving the
glucose in 100.0 kg of water
b. 0.028 m Na2CrO4 solution made by dissolving the Na2CrO4
in 1000.0 g of water
c. 0.100 m urea solution made by dissolving the urea in
500.0 g of water
2-11-16 Bell Ringer
Cinnamon Cinnamon owes its flavor and
odor to cinnamaldehyde (C9H8O).
Determine the freezing point of a
solution of 75 mg of cinnamaldehyde
dissolved in 1.00 g of benzene (Kf =
4.3°C/m; normal freezing point = 5.5°C).
2-11-16 Exit
Saccharin Determine the melting point
of an aqueous solution made by adding
186 mg of saccharin (C7H5O3NS) to 1.00
mL of water (density = 1.00 g/mL, Kf =
1.86°C/m).
2-12-16 Bell Ringer
How can measurements of osmotic
pressure, freezing point depression, and
boiling point elevation be used to find
the molar mass of a solute? Why is it
important to know whether the solute is
an electrolyte or a nonelectrolyte?
2-12-16 Exit
An unknown compound (152 mg) is dissolved
in water to make 75.0 mL of solution. The
solution does not conduct electricity and has
an osmotic pressure of 0.328 atm at 27°C.
Elemental analysis reveals the substance to
be 78.90% C, 10.59% H, and 10.51% O.
Determine the molecular formula of this
compound.
2-16-16 Bell Ringer
You have a mission…Please check with the substitute teacher to pick up
your packets. In your packets, you will discover your partner(s), rubric
for grading and responsibilities for your sections. Please refer to the
lesson plan on our class webpage to stay current on your questions and
homework. It is recommended that you create your presentation in
Google Docs! (my daughter picked your teams by random draw out of a
dog bowl so no whining)
2-16-16 Exit
How do ion–dipole interactions influence
whether an ionic compound’s heat of
solution is exothermic or endothermic?
2-17-16 Bell Ringer
The following pairs of aqueous solutions are separated by a
semipermeable membrane. In which direction will the solvent flow?
a.
A = 0.48 M NaCl; B = 55.85 g of NaCl dissolved in
1.00 L of solution
b.
A = 100 mL of 0.982 M CaCl2; B = 16 g of NaCl in
100 mL of solution
c.
A = 100 mL of 6.56 mM MgSO4; B = 5.24 g of MgCl2 in 250 mL of
solution
2-17-16 Exit
Calculate the osmotic pressure of each of the following aqueous
solutions at 27°C:
a.
10.0 g of NaCl in 1.50 L of solution
b.
10.0 mg/L of LiNO3
c.
0.222 M glucose
d.
0.00764 M K2SO4
2-18-16 Bell Ringer
Which one of the following aqueous
solutions should have the lowest freezing
point: 0.0500 m C6H12O6, 0.0300 m KBr,
or 0.0150 m Na2SO4?
2-18-16 Exit
Arrange the following solutions in order of increasing freezing
point depression:
a.
0.10 m MgCl2 in water, i = 2.7, Kf = 1.86°C/m
b. 0.20 m toluene in diethyl ether, i = 1.00, Kf = 1.79°C/m
c.
0.20 m ethylene glycol in ethanol, i = 1.00, Kf = 1.99°C/m
2-19-16 Bell Ringer
Which aqueous solution has the highest
boiling point: 0.5 m glucose, 0.5 m NaCl,
or 0.5 m CaCl2?
2-19-16 Exit
Determine the boiling point of an
aqueous solution that is 2.50 m ethylene
glycol (HOCH2CH2OH); Kb for water is
0.52°C/m. Assume that the boiling point
of pure water is 100.00°C.
2-22-16 Bell Ringer
You have 5 minutes to talk to your
neighbor about any questions you might
have on your chapters 10 & 11 learning
log. Be prepared to grade your notebooks
when the time is over.
2-22-16 Exit
Share a half sheet of paper with your neighbor.
1)
2)
3)
4)
Write the name(s) of your STEAM project group
What have you completed so far?
What is your next step?
Is there anything you need from me to assist? Yes/No and if Yes
what is it?
5) Are you presenting at STEAM April 2nd or are you presenting the
following week in class?
2-23-16 Bell Ringer
The three identical glass spheres in Figure P12.15 contain the same
number of particles at the same temperature. Rank the containers in
order of increasing number of microstates accessible to the particles
inside them.
(a)
(b)
FIGURE P12 .15
(c)
2-23-16 Exit
Which of the following molecular solutes
experience an increase in entropy when
dissolved in water? (a) CO2(g), (b) HF(g),
(c) CH3OH(ℓ), (d) CH3COOH(ℓ),
(e) C12H22O11(s)
2-24-16 Bell Ringer
Rank the compounds in each of the following groups in
order of increasing standard molar entropy (S°):
a. CH4(g), CH3CH3(g), and CH3CH2CH3(g)
b. CCl4(ℓ), CHCl3(ℓ), and CH2Cl2(ℓ)
c. CO2(ℓ), CO2(g), and CS2(g)
2-24-16 Exit
Adding sidewalk deicer (calcium
chloride) to water causes the
temperature of the water to
increase. If solid CaCl2 is the system,
what are the signs of ∆Ssys and ∆Ssurr?
2-25-16 Bell Ringer
What are the signs of ∆Ssys and ∆Suniv for
the photosynthesis of glucose from
carbon dioxide and water?
2-25-26 Exit
Do decomposition reactions tend to have
∆S°rxn values that are greater than zero or
less than zero? Why?
2-26-16 Bell Ringer
Use the standard molar entropies in Appendix 4 to
calculate the ∆S° value for each of the following
reactions of sulfur compounds.
a. H2S(g) + 3/2 O2(g) → H2O(g) + SO2(g)
b. 2 SO2(g) + O2(g) → 2 SO3(g)
c. SO3(g) + H2O(ℓ) → H2SO4(aq)
d. S(g) + O2(g) → SO2(g)
1. if H is - and  S is +  G must be negative, so spontaneous
2. if  H is + and  S is -  G must be positive, so nonspontaneous
3. if  H is - and  S is ......  G will be negative if TS is smaller than  H
......  G will be positive if TS is bigger than H
4 if H is + and S is +
..... G will be positive if TS is smaller than H
..... G will be negative if TS is bigger than H
2-26-16 Exit
Calculate the ∆S° value for the conversion of ozone to oxygen
2 O3(g) → 3 O2(g)
in the absence of Cl atoms, and compare it with the ∆S° value in
Problem 12.39.
2-29-16 Bell Ringer
What does the sign of ∆G tell you about the
spontaneity of a process?
What does the sign of ∆G tell you about the
rate of a reaction?
2-29-16 Exit
Which of the following processes is/are
spontaneous?
a. A tornado forms.
b. A broken cell phone fixes itself.
c. You get an A in this course.
d. Hot soup gets cold before it is served.
3-1-16 Bell Ringer
The values of ∆H°rxn and ∆S°rxn for the reaction
2 NO(g) + O2(g) → 2 NO2(g)
are –12 kJ and –146 J/K.
a.
b.
Use these values to calculate ∆G°rxn at 298 K.
Explain why the value of ∆S°rxn is negative.
3-1-16 Exit
Use the appropriate ∆G°f data in Appendix 4 to
calculate ∆G°rxn for the complete combustion of
methanol:
2 CH3OH(g) + 3 O2(g) → 2 CO2(g) + 4 H2O(g)
3-2-16 Bell Ringer
Are exothermic reactions spontaneous only
at low temperature? Explain your answer.
3-2-16 Exit
Volcanoes Deposits of elemental sulfur are often seen near
active volcanoes. Their presence there may be due to the
following reaction of SO2 with H2S:
SO2(g) + 2 H2S(g) → 3/8 S8(s) + 2 H2O(g)
Assuming the values of ∆H°rxn and ∆S°rxn do not change
appreciably with temperature, over what temperature range is
the reaction spontaneous?
3-3-16 Bell Ringer
Which of the following reactions is spontaneous: (i)
only at low temperatures; (ii) only at high
temperatures; (iii) at all temperatures?
a. 2 H2S(g) + 3 O2(g) → 2 H2O(g) + 2 SO2(g)
b. SO2(g) + H2O2(ℓ) → H2SO4(ℓ)
c. S(g) + O2(g) → SO2(g)
3-3-16 Exit
Methane-Producing Bacteria Methanogenic bacteria
convert liquid acetic acid (CH3COOH) into CO2(g) and
CH4(g).
a. Is this process endothermic or exothermic under
standard conditions?
b. Is the reaction spontaneous under standard
conditions?
3-4-16 Bell Ringer
What is urban smog & what can be done about it?
3-4-16
What is the effect of concentration on reaction rate?
3-7-16 Bell Ringer
Catalytic Converters and Combustion Catalytic converters in automobiles combat
air pollution by converting NO & CO into N2 & CO2:
2 CO(g) + 2 NO(g) → N2(g) + 2 CO2(g)
a. How is the rate of formation of N2 related to the rate of consumption of CO?
b. How is the rate of formation of CO2 related to the rate of consumption of NO?
c. How is the rate of consumption of CO related to the rate of consumption of
NO?
3-7-16 Exit
Write expressions for the rate of formation of products
and the rate of consumption of reactants in each of the
following reactions:
a. Cl2O2(g) → 2 ClO(g)
b. N2O5(g) → NO2(g) + NO3(g)
c. 2 INO(g) → I2(g) + 2 NO(g)
3-8-16 Bell Ringer
Reducing Nitric Oxide Emissions from Power Plants Nitric oxide (NO)
can be removed from gas-fired power-plant emissions by reaction with
methane as follows:
CH4(g) + 4 NO(g) → 2 N2(g) + CO2(g) + 2 H2O(g)
Write an equation relating each of the following pairs of rates:
a. The rate of formation of N2 to the rate of formation of CO2
b. The rate of formation of CO2 to the rate of consumption of NO
c. The rate of consumption of CH4 to the rate of formation of H2O
3-8-16 Exit
The chemistry of smog formation includes NO3 as an intermediate in
several reactions.
a. If ∆[NO3]/∆t is –2.2 × 105 mM/min in the following reaction, what is
the rate of formation of NO2?
NO3(g) + NO(g) → 2 NO2(g)
b. What is the rate of change of [NO2] in the following reaction if
∆[NO3]/∆t is –2.3 mM/min?
2 NO3(g) → 2 NO2(g) + O2(g)
3-9-16 Bell Ringer
Determine the overall order of the following rate laws and the order
with respect to each reactant.
a.
Rate = k[A]2[B]1/2
b.
Rate = k[A]2[B][C]
c.
Rate = k[A][B]3[C]1/2
3-9-16 Exit
Compounds A and B react to give a single product, C. Write the rate law
for each of the following cases and determine the units of the rate
constant by using the units M for concentration and s for time:
a. The reaction is first order in A and second order in B.
b. The reaction is first order in A and second order overall.
c. The reaction is independent of the concentration of A and second
order overall.
d. The reaction is second order in both A and B.
3-10-16 Bell Ringer
Two reactions in which there is a single reactant have nearly the same
magnitude rate constant. One is first order; the other is second order.
a. If the initial concentrations of the reactants are both 1.0 mM, which
reaction will proceed at the higher rate?
b. If the initial concentrations of the reactants are both 2.0 M, which
reaction will proceed at the higher rate?
3-10-16 Exit
Hydroperoxyl Radicals in the Atmosphere During a smog event, trace
amounts of many highly reactive substances are present in the
atmosphere. One of these is the hydroperoxyl radical, HO2, which
reacts with sulfur trioxide, SO3. The rate constant for the reaction
2 HO2(g) + SO3(g) → H2SO3(g) + 2 O2(g)
at 298 K is 2.6 × 1011 M –1 s–1. The initial rate of the reaction doubles
when the concentration of SO3 or HO2 is doubled. What is the rate law
for the reaction?
3-11-16 Bell Ringer
T (K)
203
213
223
233
243
k (M–1 s–1)
4.14 × 105
7.30 × 105
1.22 × 105
1.96 × 106
3.02 × 106
The rate constant for the reaction
NO2(g) + O3(g) → NO3(g) + O2(g)
was determined over a temperature range of 40 K, with the following
results:
a.
b.
Determine the activation energy for the reaction.
Calculate the rate constant of the reaction at 300 K.
3-11-16 Exit
What overall reaction consists of the following elementary steps?
ClO–(aq) + H2O(ℓ) → HClO(aq) + OH–(aq)
I–(aq) + HClO(aq) → HIO(aq) + Cl–(aq)
OH–(aq) + HIO(aq) → H2O(ℓ) + IO–(aq)
3-14-16 Bell Ringer
Mechanism of Ozone Destruction Ozone decomposes thermally to
oxygen in the following reaction:
2 O3(g) → 3 O2(g)
The following mechanism has been proposed:
O3(g) → O(g) + O2(g)
O(g) + O3(g) → 2 O2(g)
The reaction is second order in ozone. What properties of the two
elementary steps (specifically, relative rate and reversibility) are
consistent with this mechanism?
3-14-16 Exit
NO as a Catalyst for Ozone Destruction Explain why NO is a catalyst in
the following two-step process that results in the depletion of ozone in
the stratosphere:
(1) NO(g) + O3(g) → NO2(g) + O2(g)
(2) O(g) + NO2(g) → NO(g) + O2(g)
Overall:
O(g) + O3(g) → 2 O2(g)
3-15-16 Bell Ringer
A mixture of 13CO, 12CO2, and O2 in a sealed reaction vessel was used to
follow the reaction
Analysis of the reaction mixture after 1 day revealed the presence of
compounds with molar masses 28, 29, 32, 44, and 45 g/mol. Identify
the compounds and account for their presence.
3-15-16 Exit
At 700 K the equilibrium constant Kc for the gasphase reaction between NO and O2 forming NO2
is 8.7 × 106. The rate constant for the reverse
reaction at this temperature is 0.54 M –1 s–1. What
is the value of the rate constant for the forward
reaction at 700 K?
3-16-16 Bell Ringer
At 1045 K the partial pressures of an equilibrium mixture of H2O, H2,
and O2 are 0.040, 0.0045, and 0.0030 atm, respectively. Calculate the
value of the equilibrium constant Kp at 1045 K.
3-16-16 Exit
Analyses of an equilibrium mixture of gaseous N2O4 and NO2 gave the
following results: [NO2] = 4.2 × 10–3 M and [N2O4] = 2.9 × 10–3 M. What
is the value of the equilibrium constant Kc for the following reaction at
the temperature of the mixture?
3-17-16 Bell Ringer
The equilibrium constant Kc for the following equilibrium is 6.0 × 104 at
500 K. What is the value of Kp for this same equilibrium at 500 K?
3-17-16 Exit
3-18-16 Bell Ringer
3-18-16 Exit
At 650 K, the value of the equilibrium constant Kp for the ammonia
synthesis reaction
is 4.3 × 10–4. If a vessel contains a reaction mixture in which [N2] =
0.010 M, [H2] = 0.030 M, and [NH3] = 0.00020 M, will more ammonia
form?
3-29-16 Bell Ringer
Write the Kc expression for the following reaction:
3-29-16 Exit
Which of the following equilibria will shift toward formation of more
products if the volume of a reaction mixture at equilibrium increases by
a factor of 2?
3-30-16 Bell Ringer
3-30-16 Exit
Enough NO2 gas is injected into a cylindrical vessel to produce a partial
pressure, PNO2, of 0.900 atm at 298 K. Calculate the equilibrium partial
pressures of NO2 and N2O4, given
3-31-16 Bell Ringer
3-31-16 Exit
4-1-16 Bell Ringer
STEAM is tomorrow…Is there anyone that needs anything before we go
to set up Saturday?
4-1-16 Exit
Draw for Slots for in class STEAM Presentations…Note half class period
each for 3 days
Monday 4-4-16
First Half Class
Second Half Class
Tuesday 4-5-16
Wednesday 4-6-16
4-7-16 Bell Ringer
4-7-16 Exit
4-11-16 Bell Ringer
4-11-16 Exit
Predict which acid in the following pairs of
acids is the stronger acid: (a) HBrO or HBrO2;
(b) HClO or HBrO.
4-12-16 Bell Ringer
In principle, ethanol (CH3CH2OH) can undergo
autoionization. Propose an explanation for why the
value of the equilibrium constant for the autoionization
of ethanol is much less than that of water.
4-12-16 Exit
pH of Blood The pH of venous blood, which
carries CO2 back to the lungs, is 7.35, while
that of arterial blood is 7.45. How many
times more concentrated in H+ is venous
blood compared with arterial blood?
4-13-16 Bell Ringer
Nitric acid (HNO3) is a strong acid that is completely
ionized in aqueous solutions of concentrations ranging
from 1% to 10% (1.5 M). However, in more
concentrated solutions, part of the nitric acid is present
as un-ionized molecules of HNO3. For example, in a 50%
solution (7.5 M) at 25°C, only 33% of the molecules of
HNO3 dissociate into H+ and NO3–. What is the value of
Ka of HNO3?
4-13-16 Exit
Acid Rain II ​A newspaper reported that the “level of
acidity” in a sample taken from an extensively studied
watershed in New Hampshire in February 1998 was “an
astounding 200 times lower than the worst
measurement” taken in the preceding 23 years. What is
this difference expressed in units of pH?
4-14-16 Bell Ringer
Pyridine (C5H5N) is a particularly foulsmelling substance used in manufacturing
pesticides and plastic resins. Calculate the pH
of a 0.125 M solution of pyridine.
4-14-16 Exit
1,2-Diaminoethane, H2NCH2CH2NH2, is used
extensively in the synthesis of compounds
containing transition metals in water. If pKb1 =
3.29 and pKb2 = 6.44, what is the pH of a 2.50 ×
10–4 M solution of 1,2-diaminoethane?
4-15-16 Bell Ringer
Dozens of pharmaceuticals ranging from Cyclizine for
motion sickness to Viagra for impotence are derived
from the organic compound piperazine, whose
structure is shown in Figure P15.74.
Solutions of piperazine are basic (Kb1 = 5.38 × 10–5; Kb2 =
2.15 × 10–9). What is the pH of a 0.0133 M solution of
piperazine?
4-15-16 Exit
If the Ka1 value of chromic acid
(H2CrO4) is 0.16 and its Ka2 value is
–7
3.2 × 10 , what are the values of Kb1
2–
and Kb2 of the CrO4 anion?
4-19-16 Bell Ringer
What is the solubility of silver iodide in
grams per milliliter at a temperature at
–16
which its Ksp = 1.50 × 10 ?
4-19-16 Exit
Will strontium sulfate precipitate at
25°C when 345 mL of a solution that
2+
is 0.0100 M in Sr (aq) is added to 75
mL of 0.175 M K2SO4?
4-20-16 Bell Ringer
Do all titrations of a strong base with a
strong acid have the same pH at the
equivalence point?
4-20-16 Exit
Alkaline Hot Springs In an alkalinity titration of a
100.0 mL sample of water from a hot spring, 2.56 mL of
a 0.0355 M solution of HCl is needed to reach the first
equivalence point (pH = 8.3) and another 10.42 mL is
needed to reach the second equivalence point (pH =
4.0). If the alkalinity of the spring water is due only to
the presence of carbonate and bicarbonate, what are
the concentrations of each?
4-21-16 Bell Ringer
A voltaic cell is based on the reaction between Ag+(aq)
and Ni(s), producing Ag(s) and Ni2+(aq).
a. Write the anode and cathode half-reactions.
b. Write a balanced cell reaction.
c. Diagram the cell.
4-21-16 Exit
A piece of cadmium is placed in a solution in
which [Cd2+] = [Sn2+] = 1.00 M. Will the
following reaction proceed spontaneously?
Cd(s) + Sn2+(aq) → Cd2+(aq) + Sn(s)
4-22-16 Bell Ringer
Starting with the appropriate standard free energies of
formation from Appendix 4, calculate the values of ∆G°
and E°cell of the following reactions:
a.
b.
FeO(s) + H2(g) → Fe(s) + H2O(ℓ)
2 Pb(s) + O2(g) + 2 H2SO4(aq) → 2 PbSO4(s) + 2 H2O(ℓ)
4-22-16 Exit
Starting with the standard potentials listed in
Appendix 6, calculate the values of E°cell and ∆G°
of the following reactions.
a.
b.
Fe(s) + Cu2+(aq) → Fe2+(aq) + Cu(s)
Ag(s) + Fe3+(aq) → Ag+(aq) + Fe2+(aq)
4-25-16 Bell Ringer
Calculate the Ecell value at 298 K for the cell based on
the reaction
Cu(s) + 2 Ag+(aq) → Cu2+(aq) + 2 Ag(s)
when [Ag+] = 2.56 10–3 M and [Cu2+] = 8.25 10–4 M.
4-25-16 Exit
Which of the following voltaic cells will produce the
greater quantity of electric charge per gram of anode
material?
Zn(s) + MnO2(s) + H2O(ℓ) → ZnO(s) + Mn(OH)2(s)
or
Li(s) + MnO2(s) → LiMnO2(s)
5-2-16 Bell Ringer
A battery charger used to recharge the NiMH
batteries in a digital camera can deliver as much
as 0.50 A of current to each battery. If it takes 100
min to recharge one battery, how much Ni(OH)2
(in grams) is oxidized to NiO(OH)?
5-2-16 Exit
Molten carbonate fuel cells fueled with H2 convert as
much as 60% of the free energy released by the
formation of water from H2 and O2 into electrical
energy. Determine the quantity of electrical energy
obtained from converting 1 mole of H2 into H2O(ℓ) in
such a fuel cell.
5-3-16 Bell Ringer
Balance the following half-reactions by adding the appropriate number
of electrons. Which are oxidation half-reactions and which are
reduction half-reactions?
a.
Fe2+(aq) → Fe3+(aq)
b.
AgI(s) → Ag(s) + I–(aq)
c.
VO2+(aq) + 2 H+(aq) → VO2+(aq) + H2O(ℓ)
d.
I2(s) + 6 H2O(ℓ) → 2 IO3–(aq) + 12 H+(aq)
5-3-16 Exit
From the table of standard reduction potentials in
Appendix 6,
a. Select an oxidizing agent that will oxidize Cr(s) to Cr3+(aq)
but not Cd(s) to Cd2+(aq).
b. Select a reducing agent that will reduce Br2(ℓ) to Br–(aq) but
not I2(s) to I–(aq).
5-5-16 Bell Ringer
Molecules of which of the compounds in Table
19.1 form hydrogen bonds with each other?
5-5-16 Exit
Which of the molecules in Figure P19.36 are constitutional isomers of
heptane (C7H16)? Name these molecules.
5-6-16 Bell Ringer
Using the average bond strengths given in Appendix 4,
estimate the molar heat of hydrogenation,
∆Hhydrogenation, for the conversion of C2H2 to C2H6.
CH[TRIPLEBOND]CH(g) + 2 H2(g) → CH3CH3(g)
5-6-16 Exit
Using data in Appendix 4, calculate ∆Hrxn for the production of
acetylene from the reaction between calcium carbide and water, given
that the ∆H°f of CaC2 is –59.8 kJ/mol:
CaC2(s) + 2 H2O(ℓ) → C2H2(g) + Ca(OH)2(s)
Is this an endothermic or an exothermic reaction?
5-9-16 Bell Ringer
Does 1 mole of gaseous benzene (C6H6)
have a higher or lower fuel value than 3
moles of acetylene gas (C2H2)?
5-9-16 Exit
Which of the compounds in Figure P19.86 are alcohols and which ones
are ethers? Place them in order of increasing vapor pressure at 25°C.
5-10-16 Bell Ringer
Determine the ∆H°rxn values of these combustion reactions of
methylamine. (∆H°f,CH3NH2 = –23.0 kJ/mol.)
4 CH3NH2(g) + 13 O2(g) → 4 CO2(g) + 4 NO2(g) + 10 H2O(ℓ)
4 CH3NH2(g) + 6 O2(g) → 4 CO2(g) + 4 NH3(g) + 4 H2O(ℓ)
5-10-16 Exit
Propanal and acetone (2-propanone) have the same molecular
formula, C3H6O, but different structures (Figure P19.104). Which
compound is a ketone?
5-11-16 Bell Ringer
Identify the amino acids in the tripeptides shown in Figure P20.24.
5-11-16 Exit
Describe two ways in which an inhibitor can
reduce the catalytic properties of an enzyme.
5-12-16 Bell Ringer
Which, if any, of the structures in Figure
P20.48 are ß isomers?
5-12-16 Exit
Salad Dressing Salad dressings containing oil and
vinegar quickly separate on standing. Explain the
observed separation of layers based on the structure
and properties of aqueous vinegar and oil.
5-13-16 Bell Ringer
For each of the pairs of fatty acids in
Figure P20.62, indicate whether they are
structural isomers, stereoisomers, or
unrelated compounds.
5-13-16 Exit
Why does a codon consist of a sequence of
three, and not two, ribonucleotides?
5-16-16 Bell Ringer
In transcription, a segment of the strand of DNA
that is transcribed has the sequence T-C-G-G-T-A.
What is the corresponding sequence of
nucleotides on the messenger RNA that is
produced in transcription?
5-16-16 Exit
Why is the discovery of enzymes
that catalyze cellulose hydrolysis a
worthwhile objective?