Chem 122 Final Wxam Questions With verified Answers
2PbS(s)+3O2(g)→2PbO(s)+2SO2(g), ΔH∘=−844 kJ, ΔS∘=−165 J/K
Express the Gibbs free energy in kilojoules to three significant digits.
is it spontaneous - ANSWER--795kJ
yes
.2POCl3(g)→2PCl3(g)+O2(g), ΔH∘=572 kJ, ΔS∘=179 J/K
Express the Gibbs free energy in kilojoules to three significant digits.
Is it spontaneous - ANSWER-519kJ
no
.A ______________ cubic structure has more empty space than a
____________ cubic one. The more empty space, the ______________
the solid. - ANSWER-body-centered, face-centered, less dense
,.A buffer solution with a pH of 5.56 is prepared with the same
volumes of 0.50 M HC2H3O2 and ________ M NaC2H3O2. The Ka of
HC2H3O2 is 1.8 ⋅ 10-5.
1.6×10−6
6.5
1.6
3.3
9.9×10−11 - ANSWER-3.3
.A certain reaction has ΔH∘=35.1kJ and ΔS∘=86.0J/K.
a.) Is the reaction exothermic or endothermic?
exothermic
endothermic
b.) Does the reaction lead to an increase or decrease in the disorder of
the system?
increase
decrease
,c.) Calculate ΔG∘ for the reaction at 298 K.
d.) Is the reaction spontaneous at 298 K under standard conditions?
yes
no - ANSWER-endothermic
increase
9.47kJ
no
.A mixture of hydrogen and nitrogen, which produces ammonia (NH3)
in a reaction vessel, is allowed to reach equilibrium at a given
temperature. The equilibrium mixture of gases contained 0.254 M
NH3, 1.85 M N2, and 9.26 M H2. Calculate the equilibrium constant, Kc
at this temperature.
2.28 × 104
3.77 × 10-3
, 4.39 × 10-5
1.73 × 10-4 - ANSWER-4.39 x 10^-5
.A particular sample of vinegar has a pH of 3.10.
If acetic acid is the only acid that vinegar contains (Ka=1.8×10−5),
calculate the initial concentration of acetic acid in the vinegar. -
ANSWER-3.6×10−2 M CH3COOH
.A radioisotope of technetium is useful in medical imaging techniques.
A sample initially contains 80.0 mg of this isotope. After 24.0 h, only
5.0 mg of the technetium isotope remains. What is the half-life of the
isotope?
3.0 h
6.0 h
12.0 h
16.0 h
24.0 h - ANSWER-6.0 h
.A reversible process is one that ________.
2PbS(s)+3O2(g)→2PbO(s)+2SO2(g), ΔH∘=−844 kJ, ΔS∘=−165 J/K
Express the Gibbs free energy in kilojoules to three significant digits.
is it spontaneous - ANSWER--795kJ
yes
.2POCl3(g)→2PCl3(g)+O2(g), ΔH∘=572 kJ, ΔS∘=179 J/K
Express the Gibbs free energy in kilojoules to three significant digits.
Is it spontaneous - ANSWER-519kJ
no
.A ______________ cubic structure has more empty space than a
____________ cubic one. The more empty space, the ______________
the solid. - ANSWER-body-centered, face-centered, less dense
,.A buffer solution with a pH of 5.56 is prepared with the same
volumes of 0.50 M HC2H3O2 and ________ M NaC2H3O2. The Ka of
HC2H3O2 is 1.8 ⋅ 10-5.
1.6×10−6
6.5
1.6
3.3
9.9×10−11 - ANSWER-3.3
.A certain reaction has ΔH∘=35.1kJ and ΔS∘=86.0J/K.
a.) Is the reaction exothermic or endothermic?
exothermic
endothermic
b.) Does the reaction lead to an increase or decrease in the disorder of
the system?
increase
decrease
,c.) Calculate ΔG∘ for the reaction at 298 K.
d.) Is the reaction spontaneous at 298 K under standard conditions?
yes
no - ANSWER-endothermic
increase
9.47kJ
no
.A mixture of hydrogen and nitrogen, which produces ammonia (NH3)
in a reaction vessel, is allowed to reach equilibrium at a given
temperature. The equilibrium mixture of gases contained 0.254 M
NH3, 1.85 M N2, and 9.26 M H2. Calculate the equilibrium constant, Kc
at this temperature.
2.28 × 104
3.77 × 10-3
, 4.39 × 10-5
1.73 × 10-4 - ANSWER-4.39 x 10^-5
.A particular sample of vinegar has a pH of 3.10.
If acetic acid is the only acid that vinegar contains (Ka=1.8×10−5),
calculate the initial concentration of acetic acid in the vinegar. -
ANSWER-3.6×10−2 M CH3COOH
.A radioisotope of technetium is useful in medical imaging techniques.
A sample initially contains 80.0 mg of this isotope. After 24.0 h, only
5.0 mg of the technetium isotope remains. What is the half-life of the
isotope?
3.0 h
6.0 h
12.0 h
16.0 h
24.0 h - ANSWER-6.0 h
.A reversible process is one that ________.
