Physical Chemistry Answers

Question 3 : Which of these is not an extensive property of a system?
Mass
Energy
Density
Volume

Question 4 : Which of the following statements about enthalpy is incorrect?

Δ
H
ΔH
is the enthalpy change at constant pressure
Reactions which absorb heat have a positive DH
Enthalpy and internal energy of a system are always identical
enthalpy is a state function

Question 1 : The zeroth law of thermodynamics is based on the concept of
entropy
Conservation of energy
absolute zero temperature
thermodynamic equivalence

Question 2 : Which of these does not depict thermodynamics?
Rate of reaction
Performance of car engine
Melting of ice
Boiling water for coffee

Question 7 : All of the following statements concerning entropy are true EXCEPT
entropy is zero for elements under standard conditions.
entropy values are greater than or equal to zero.
a positive change in entropy denotes a change toward greater disorder.
entropy is a state function.
Question 8 : In a reaction in which the rate of the reverse reaction is equal to the rate of the forward reaction, a state of ____________ is attained.
total entropy
thermodynamics
dynamic equilibrium
product reversibility

Question 5 : The temperature remains constant as energy is added to a substance. How may the substance be changing?
From a gas to a solid
From a liquid to a solid
Change in the amoung of kinetic energy
From a liquid to a gas
Question 6 : The heat of combustion for 1 mole of carbon to carbon dioxide is -410 kJ. How many kJ of heat would be liberated from the complete combustion of 60.0 g of carbon?
-24,600 kJ
-82 kJ
-2050 kJ
650.2 kJ

Question 3 : A reaction with a negative value of
Δ
G
ΔG is said to be
Reversible
At equilibrium
Spontaneous
Non-spontaneous
Question 4 : Of the following product-favoured processes, which are endothermic? 1. the combustion of methane to produce water and carbon dioxide. 2. the expansion of an ideal gas. 3. the melting of ice at temperatures greater than 0ºC.
2 only
2 and 3
3 only
1 only

1 : Calculate the standard entropy change for the following reaction,
2
A
g
2
O
(
s
)
→
4
A
g
(
s
)
+
O
2
(
g
)
2Ag2O(s)→4Ag(s)+O2(g); given
S
o
[
A
g
2
O
]
So[Ag2O] = 121.3 J/K·mol,
S
o
So[Ag(s)] = 42.6 J/K·mol, and
S
o
[
O
2
(
g
)
]
So[O2(g)] = 205.1 J/K·mol.
-126.4 J/K
+126.4 J/K
-205.1 J/K
+132.9 J/K
Question 2 : A statement of the second law of thermodynamics is that
the enthalpy of reaction is the difference between product and reactant enthalpies.
energy is conserved in a chemical reaction.
spontaneous reactions are always exothermic.
the entropy of the universe is continually increasing.

Question 17 : Which of the following is not a state function?
free energy
entropy
work
enthalpy
Question 18 : 1. 43.4 kcal of heat is required to decompose 2 mole of mercury(II) oxide according to the equation
2
H
g
O
(
s
)
→
2
H
g
(
l
)
+
O
2
(
g
)
2HgO(s)→2Hg(l)+O2(g)
. What quantity of energy is required to decompose 10.8 g of HgO? (Hg = 200.59, O = 16)
2.17 kcal
1.09 kcal
468.72 kJ
0.545 kJ
Question 19 : Which of these followings would lead to an increase in the internal energy of a system?
Work done on the system
Loss of heat from the system
Work done by the system
Adiabatic expansion of the system
Question 20 : A process in which no heat is allowed to enter or leave a system is termed –
Isochoric
isobaric
Isothermal
Adiabatic

Question 13 : If a gas absorbs 1000 J of heat and expands by 0.5
d
m
3
dm3 against a constant pressure of 4 atms (1 atm = 100000 Pa), then the change in internal energy is approximately
-800 J
1200 J
-1200 J
800 J
Question 14 : The specific heat of silver is 0.0565
c
a
l
/
g
/
o
C
cal/g/oC. Assuming no loss of heat to the surroundings or to the container, calculate the final temperature when 100 g of silver at 40
o
C
oC is immersed in 60 g of water at 10
o
C
oC.
21.6
o
C
oC.
25
o
C
oC
12.6
o
C
oC
16.2
o
C
oC
Question 15 : The molar heat capacity of Al is 24.4 J/mol/
o
C
oC. How much heat energy is required to heat 100 g of Al from 20
o
C
oC to 80
o
C
oC? (Al = 27)
5422 J
813000 J
146000 J
30000 J
Question 16 : A process taking place at constant pressure is termed –
Adiabatic
Isothermal
Isobaric
Isochoric

Question 10 : Which of the following statements describes an isolated system?
No exchange of matter and energy with the surrounding is possible
exchange of both matter and energy with the surrounding is possible
only exchange of matter with the surrounding is possible
only exchange of energy with the surrounding is possible
Question 11 : Calculate the
Δ
H
ΔH value of the reaction:
H
C
l
+
N
H
3
→
N
H
4
C
l
HCl+NH3→NH4Cl
Δ
H
o
ΔHo values for HCl,
N
H
3
NH3 and
N
H
4
C
l
NH4Cl are -92.30, -80.29 and -314.4 respectively
-486.99
252.88
141.8
-141.8
Question 12 : Which of these is true of an isochoric system?
Volume remains constant
Heat is allowed into the system but not allowed out of the system
Takes place at constant temperature
Pressure is not constant

Question 6 : Which of the followings is not a type of system?
Open
Closed
Intensive
Isolated
Question 7 : One mole of an ideal gas is heated at a constant pressure of 101300 N
m
2
m2, from 273.2 K to 373 K. Calculate the work involved R = 8.314 J/mol/K).
8.314 J/mol
831.4 J/mol
83.14 J/mol
8314 J/mol
Question 8 : Which of the following expressions is associated with the law of conservation of energy?
dE = q + w
q = mCdT
dG = dH – TdS
H = E + PV
Question 9 : Which of the following statements is correct?
Temperature is an extensive property while heat is an intensive property
temperature is an intensive property while heat is an extensive property
both temperature and heat are extensive properties.
both temperature and heat are intensive properties