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Test: Thermodynamics And Thermochemistry - 2

30 Questions MCQ Test Physical Chemistry | Test: Thermodynamics And Thermochemistry - 2

Description

Attempt Test: Thermodynamics And Thermochemistry - 2 | 30 questions in 90 minutes | Mock test for Chemistry preparation | Free important questions MCQ to study Physical Chemistry for Chemistry Exam | Download free PDF with solutions

QUESTION: 1

Enthalpy change for a reaction does not depend upon:

A.
The physical states of reactants and products
B.
Use of different reactants for the same product
C.
The nature of the intermediate reaction steps
D.
The differences in initial or final temperature of involved substances

Solution:

QUESTION: 2

The heat of combust ion of carbon to CO₂ is –393 KJ/mol. The heat released upon format ion of 35.2 g of CO₂ from carbon and oxygen gas is:

A.
+ 315 KJ
B.
– 31.5 KJ
C.
– 315 KJ
D.
31.5 KJ

Solution:

QUESTION: 3

Consider the reaction:

Carried out at constant temperature and pressure. If ΔH and ΔU are enthalpy and internal energy changes for the reaction, which of the following expressions is true?

A.
ΔH = 0
B.
ΔH = ΔU
C.
ΔH < ΔU
D.
ΔH > ΔU

Solution:

QUESTION: 4

The work done in ergs for the reversible expansion of one mole of an ideal gas from a volume of 10L to 20L is:

Solution:

Final volume V₂=20L

initial volume V₁=10L

W = 2.303 nRTln(V₂/V₁)

= 1 x 298 x 10⁷x 8.314 x 2.303 log2

QUESTION: 5

Work done during isothermal expansion of 1 mole of an ideal gas from 10 atm to 1 atm at 300K is:

A.
4938.8 J
B.
4138.8 J
C.
5744 J
D.
6257.2 J

Solution:

QUESTION: 6

ΔE° of combustion of isobut ylene is x KJ mol^-1. The value of ΔH° is:

A.
= ΔE°
B.
< ΔE°
C.
= 0
D.
> ΔE°

Solution:

QUESTION: 7

The free energy change for a reversible reaction at equilibrium is:

A.
Large positive
B.
Small negative
C.
Small Positive
D.
Zero

Solution:

QUESTION: 8

The heat of neutralization of a strong acid and a strong alkali is 57.0 KJ mol^–1. The heat released when 0.5 mole of HNO₃ solution is mixed with 0.2 mole of KOH is:

A.
57.0 KJ
B.
11.4 KJ
C.
28.5 KJ
D.
34.9 KJ

Solution:

QUESTION: 9

Heat of formation of H₂O is –286 KJ per mole and H₂O₂ is –188 KJ mol^–1. The enthalpy change for the reaction

A.
- 196 KJ
B.
196 KJ
C.
984 KJ
D.
–984 KJ

Solution:

ΔH_reaction=(∑H_products)−(∑H_reactants)

Δ H_reaction=[(ΔH_O2)+(ΔH_H2O)]−[ΔH_H2O2]

ΔH_O2=0,ΔH_H2O=−286KJ per mole, ΔH_H2O2=−188KJ per mole

put the values ,

ΔH_{reaction}=-196 KJ per mole

QUESTION: 10

The species which by definition has ZERO standard molar enthalpy of formation at 298 K is

A.
Br₂(g)
B.
Cl₂(g)
C.
H₂O(g)
D.
CH₄(g)

Solution:

QUESTION: 11

Given that bond energies of H–H and Cl–Cl are 430 and 240 KJ mol^–1 respectively, and ΔH_f for HCl is -90 KJ mol^-1. Bond enthalpy of HCl is:

A.
290 KJ mol^-1
B.
425 KJ mol^-1
C.
380 KJ mol^-1
D.
245 KJ mol^-1

Solution:

QUESTION: 12

Hess’s Law deals with:

A.
A change in heat of reaction
B.
Rate of reaction
C.
Equilibrium constant
D.
Influence of pressure on volume of gas

Solution:

QUESTION: 13

One mole of methanol when burnt in O₂ gives out 723 KJ mol^–1 heat. If one mole of O₂ is used, what will be the amount of heat observed:

A.
-723 KJ
B.
-924 KJ
C.
-482 KJ
D.
-241 KJ

Solution:

(1) CH₃OH +3232O₂→→CO₂ + 2H₂O, ΔH∆H=-723 kJ

The heat evolved for one mole of oxygen = -723x2/3 = -482 kJ

QUESTION: 14

The enthalpy and entropy change for the reaction:

Are 30 KJ mol^–1 and 105 JK^–1mol^–1 respect ively. The temperature at which the reaction will be in equilibrium is:

A.
285.7 K
B.
273 K
C.
450 K
D.
300 K

Solution:

QUESTION: 15

The change in the entropy for the fusion of 1 mole of ice is:

(Melting point of ice = 273 K, molar enthalpy of fusion of ice = 6.0 KJ mol^–1):

A.
11.73 JK^–1mol^–1
B.
18.84 JK^–1mol^–1
C.
21.97 JK^–1mol^–1
D.
24.47 JK^–1mol^–1

Solution:

Change in Entropy = (Enthaply of fusion) /T (Temperature)

= 60*10³/ 273

= 21.97 J/K/mol

QUESTION: 16

For a spontaneous process, the correct statement is:

A.
Entropy of the system always increases.
B.
Free energy of the system always increases.
C.
Total entropy change is always negative.
D.
Total entropy change is always positive.

Solution:

QUESTION: 17

The abso lute enthalpy of neutralization of the reaction:

A.
Less than –57.33 KJ mol^–1
B.
–57.33 KJ mol^–1
C.
Greater than –57.33 KJ mol^–1
D.
57.33 KJ mol^–1

Solution:

QUESTION: 18

For the reaction of one mole of zinc dust with one mole of sulphuric acid in a bomb calorimeter, ΔU and W corresponds to:

A.
ΔU < 0, W = 0
B.
ΔU < 0, W < 0
C.
ΔU > 0, W = 0
D.
ΔU > 0, W > 0

Solution:

QUESTION: 19

Standard enthalpy and standard entropy changes for the oxidation of NH₃ at 298 K are –382.64 KJ mol^–1 and – 145.6 JK^–1mol^–1, respectively. Standard Gibb’s energy change for the same reaction at 298 K is:

A.
–2221.1 KJmol^–1
B.
–339.3 KJmol^–1
C.
–439.3 KJmol^–1
D.
–523.2 KJmol^–1

Solution:

QUESTION: 20

ΔG = ΔH-TΔS was given by:

A.
Faraday
B.
Kirchhoff
C.
Einstein
D.
Gibbs-Helmholtz

Solution:

QUESTION: 21

The heat capacity of 10 mol of an ideal gas at a certain temperature is 300 JK^–1 at constant pressure. The heat capacity of the same gas at the same temperature and at constant volume would be:

A.
383 JK^–1
B.
217 JK^–1
C.
134 JK^–1
D.
466 JK^–1

Solution:

QUESTION: 22

The internal pressureof a real gas is related to the compressibility factor

Solution:

QUESTION: 23

Entropy is:

(I) It is the degree of disorder of randomness in a system
(II) Entropy is a state function and mixing is always positive
(III) Entropy is a intensive property
(IV) Entropy of solid is minimum and gases is maximum
(V) Entropy increase wit h temperature, complexity and atomicity

The correct statement is:

A.
I, II, III & IV
B.
I, II, IV, V
C.
II, III, IV
D.
I, III, V

Solution:

QUESTION: 24

From the following pairs, choose the substances with the higher entropy per mole at a given temperature:

(I) O₂ gas at 5 atm or O₂ gas at 0.5 atm
(II) Br₂ (L) or Br₂ (g)

A.
O₂ gas at 5 atm (II) Br₂ (L)
B.
O₂ gas at 0.5 atm (II) Br₂ (L)
C.
O₂ gas at 5 atm (II) Br₂ gas
D.
O₂ gas at 0.5 atm (II) Br₂ gas

Solution:

QUESTION: 25

For the gaseous substance

Solution:

QUESTION: 26

Among the following, the system require higher amount of thermal energy to giving the temperature 80⁰C:

A.
200 gm at 40⁰C
B.
100 gm at 20⁰C
C.
150 gm at 50⁰C
D.
300 gm at 30⁰C

Solution:

QUESTION: 27

What is the internal pressure for 4 mole of Vander Waals gas:

A.
Zero
B.
a/V²
C.
4a/V²
D.
16a/V²

Solution:

QUESTION: 28

Which of the following statement is correct:

A.
I, II, & IV
B.
I, II, III, & IV
C.
II, & III
D.
I, III, & IV

Solution:

Correct Answer :- a

Explanation : The magnitude of the work for the isothermal process for both expansion and compression is greater than the magnitude of the work for the adiabatic process.

As we know that PV = constant

The work done by the gas is equal to the area under the relevant pressure -volume isotherm.

P_iso > P_adia

V_iso> V_adia

W_iso > W_adia

QUESTION: 29

A piston-cylinder contains 0.5 kg of air at 500 kPa and 500 K. The air expands in a process so the pressure is linearly decreasing with volume to a final state of 100 kPa and 300 K. Find the work in the process.