Question

**1. The standard enthalpy of formation of phenol is
-165.0 kJ/mol. Calculate its standard enthalpy of combustion.
[Express your answer in units of kilojoules per mole,
kJ/mol]**

C6H5OH + 7O2 --> 6 CO2 + 3H2O

ΔHc = 6ΔHf(CO2) + 3ΔHf(H2O) - ΔHf(C6H5OH) - 7ΔHf(O2)

**2. Calculate the work done on a closed system consisting
of 50.0 grams of argon, assumed ideal, when it expands isothermally
and reversibly from a volume of 5.00 L to a volume of 10.00 L at a
temperature of 298 K. [Express your answer in units of kiloJoules,
kJ]**

w = -nRT ln(V2/V1)

**3. The heat capacity of a substance is often reported in
the form C _{p,m} = a + bT + c/T^{2}. Use this
expression to make a more accurate estimate of the change in molar
enthalpy of carbon dioxide when it is heated from 15°C to 37°C,
given a = 44.22 J K^{−1} mol^{−1}, b = 8.79 ×
10^{−3} J K^{−2} mol^{−1}, and c = −8.62 ×
105 J K mol^{−1}. Give your answer in the units of
J/mol.**

dH = C_{p}dT.

Answer #1

Calculate ΔG∘ (in kJ/mol) for the following reaction at 1 atm
and 25 °C:
C2H6 (g) + O2 (g) →
CO2 (g) + H2O (l) (unbalanced)
ΔHf C2H6 (g) = -84.7 kJ/mol; S
C2H6 (g) = 229.5 J/K⋅mol;
ΔHf ∘ CO2 (g) = -393.5 kJ/mol; S
CO2 (g) = 213.6 J/K⋅mol;
ΔHf H2O (l) = -285.8 kJ/mol; SH2O
(l) = 69.9 J/K⋅mol;
SO2 (g) = 205.0 J/K⋅mol

The standard enthalpy of formation of benzoic acid,
C6H5COOH, is −385kJ mol−1 at 298
K. Calculate the standard enthalpy of combustion of benzoic acid at
this temperature, given that the standard enthalpy of formation of
liquid water, H2O is −285.8 kJ mol−1 and
gaseous carbon dioxide, CO2, is −393.51 kJ
mol−1.
A
−294.3 kJ mol−1
B
−3997kJ mol−1
C
−3227.0 kJ mol−1
D
2282.2 kJ mol−1

Part A
Calculate the standard enthalpy change for the reaction
2A+B⇌2C+2D
where the heats of formation are given in the following
table:
Substance
ΔH∘f
(kJ/mol)
A
-227
B
-399
C
213
D
-503
Express your answer in kilojoules.
Answer= 273kJ
Part B:
For the reaction given in Part A, how much heat is absorbed when
3.70 mol of A reacts?
Express your answer numerically in kilojoules.
Part C:
For the reaction given in Part A, ΔS∘rxn is 25.0 J/K ....

The enthalpy of combustion of octane is 5074.9 kJ/mol and its
density is 703 kg/m3. On a mild winter day a room of volume 40 m3
needs to be warmed up from 10 to 20 OC? (Consider: cair = 0.718 J/g
K; dair = 1.225 g/L).
1)How much heat is needed?
A) 27 kJ B) 35 kJ C) 49 kJ D) 57 kJ E) None of the above
2) How much octane needs to be burned?
A) 0.845 L B)...

When 120 mg of naphthalene
(C10H8; ΔcH = -5157 kJ mol-1) was burned in a constant
volume calorimeter, the temperature rose by 3.05 K. What is the
effective heat capacity of the calorimeter? When 10.0 mg of phenol
(C6H5OH) was burned in the calorimeter, the temperature increased
by 2.05 K. What is the ΔcH
for phenol?

The standard enthalpy of formation
of the fumarate ion is ∆fHo = -777.4 kJ
mol-1. If the standard enthalpy change of the
reaction,
fumarate2- (aq) +
H2(g) → succinate2- (aq), is 131.4 kJ
mol-1, what is the enthalpy of formation of the
succinate ion?

a. The standard enthalpy of vaporization of an inorganic
compound is 38.9 kJ/mol. If the temperature at which this phase
change occurs is 221.72 °C, determine ΔS°vap (in
J/mol/K) for this compound. Report your answer to three significant
figures.
b. The entropy of freezing of an organic compound is -21.0
J/mol/K. If ΔH°freez is -14.01 kJ/mol, determine the
temperature (in K) at which this phase change occurs. Report your
answer to two decimal places

9. Use the following experimentally derived combustion
data to calculate the standard molar enthalpy of formation
(ΔH°f ) of liquid methanol (CH3OH) from its
elements.
2 CH3OH(l) + 3 O2(g) → 2
CO2(g) + 4 H2O(l)
ΔH°rxn = −1452.8 kJ
C(graphite) + O2(g) →
CO2(g)
ΔH°rxn = −393.5 kJ
2 H2(g) + O2(g) → 2
H2O(l)
ΔH°rxn = −571.6 kJ
(1) −238.7 kJ/mol (2) 487.7
kJ/mol (3) −548.3 kJ/mol
(4) 20.1 kJ/mol
(5) 47.1 kJ/mol

1.) Using enthalpies of formation, calculate the standard change
in enthalpy for the thermite reaction. The enthalpy of formation of
Fe3O4 is −1117 kJ/mol.
8 Al(s) + 3 Fe3O4(s) → 4 Al2O3(s) + 9 Fe(s)
2. a) Nitroglycerin is a powerful explosive, giving four
different gases when detonated.
2 C3H5(NO3)3(l) → 3 N2(g) + 1/2 O2 (g) + 6 CO2(g) + 5 H2O(g)
Given that the enthalpy of formation of nitroglycerin, ΔHf°, is
−364 kJ/mol, calculate the energy (heat at...

Part A
Calculate the enthalpy change, ΔH, for the process in
which 44.0 g of water is converted from liquid at 7.6 ∘C to vapor
at 25.0 ∘C .
For water, ΔHvap = 44.0 kJ/mol at 25.0 ∘C and
s = 4.18 J/(g⋅∘C) for H2O(l)
Express your answer numerically in kilojoules.
Part B
How many grams of ice at -11.0 ∘C can be completely converted to
liquid at 9.4 ∘C if the available heat for this process is
5.66×103 kJ...

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