Tag: introduction to thermodynamics

Questions Related to introduction to thermodynamics

The state of gas can be described by quoting the relationship between_____________.

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. pressure, volume, temperature

  2. temperature, amount, pressure

  3. amount, volume, temperature

  4. pressure, volume, temperature, amount

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Correct Option: D
Explanation:

The pressure $(P)$, volume $(V)$, temperature $(T)$, amount $(n)$ etc. are the state variables or state functions.

Select incorrect statement(s):

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. A closed system with all adiabatic boundaries must be an isolated system

  2. Total heat exchange in a cyclic process may be zero

  3. Entropy of a closed system is maximum at equilibrium

  4. Molar gibb's Energy is an extensive property

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Correct Option: A
Explanation:
Since heat is energy, only two systems can stop it from crossing the boundary closed and isolated system. So yes, adiabatic process can happen in an isolated system. But all adiabatic process need not happen in an isolated system, it can happen in a closed system also.

Two closed vessel $A$ and $B$ of equal volume of $8.21L$ are connected by a narrow tube of negligible volume with open valve. The left hand side container id found to contain $3\ mole \, CO _2$ and $2\ mole$ of $He$ at $400K$. What is the partial pressure of $He$ in vessel $B$ at $500K$?

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. 2.4 atm

  2. 8 atm

  3. 12 atm

  4. None of these

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Correct Option: B
Explanation:

partial pressure of $He$ in vessel $B$, 

$PV = nRT$
$P _{He} = \dfrac{nRT}{V} = \dfrac{2\times 8.314\times 400}{8.21} =8atm$

Ammonium carbamate dissociates as ${ NH } _{ 2 }COON{ H } _{ 4\left( s \right)  }\leftrightharpoons 2N{ H } _{ 3\left( g \right)  }+{ CO } _{ 2\left( g \right)  }$. In a closed vessel containing ammonium carbamate in equilibrium, ammonia is added such that the partial pressure of ${ NH } _{ 3 }$ now equals to the original total pressure. The ratio of total pressure now to the original pressure is :

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. $\frac { 27 }{ 31 } $

  2. $\frac { 31 }{ 27 } $

  3. $\frac { 4 }{ 9 } $

  4. $\frac { 5 }{ 9 } $

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Correct Option: B

If the density of a certain gas at $30^oC$ and $768 \ torr$ is $1.35 \ kg/{m}^{3}$, the density at STP would be:

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. $1.48 \ kg/{m}^{3}$

  2. $1.58 \ kg/{m}^{3}$

  3. $1.25 \ kg/{m}^{3}$

  4. $1.4 \ kg/{m}^{3}$

Show answer
Correct Option: A
Explanation:
From Ideal gas law,

$PM = dRT$

$P _1 = 768\ torr$
$T _1 = 30^0\ C = 303\ K$
$d _1 = 1.35 kg/ m^3$

At STP, 
$T _2 = 273\ K$
$P _2 = 760\ torr$

$\dfrac{P _1}{P _2} = \dfrac{d _1T _1}{d _2T _2}$

$\dfrac{768}{760} = \dfrac{1.35\times 303}{d _2\times 273}$

$d _2 = 1.48 kg/m^3$

Hence, option A is correct.

$5$ moles of $SO _{2}$ and 5 moles of $O _{2}$ are allowed to react to form $SO _{3}$  in a closed vessel. At the equilibrium stage, $60\%$ $SO _{2}$ is used up. The total number of moles of $SO _{2}$, $O _{2}$ and $SO _{3}$ in the vessel now is

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. $10.5$

  2. $10.0$

  3. $8.5$

  4. $3.9$

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Correct Option: B

For an isolated system, the wall/boundary separating the system from surrounding must be

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. rigid

  2. impermeable

  3. adiabatic

  4. diathermal

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Correct Option: A,B,C

Assertion: Heat is not a state function

Reason: The change of heat depends upon the

path followed

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. both A and R are true and R is the correct explanation of A.

  2. both A and R are true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. both A and R are false.

Show answer
Correct Option: A
Explanation:

Heat is a path function. The change of heat depends upon the path followed

Which of the following statement(s) is/are incorrect?

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. For a closed system at rest with no fields, the sum of $q+w$ has the same value for every process that goes from a given state 1 to a given state 2

  2. If a closed system at rest in the absence of external field undergoes an adiabatic process that has $w=0$, then the temperature of system must remain constant

  3. A change in state from state 1 to state 2 produces a greater increase in entropy of the sytem when carried out irreversible than when carried out reversibly

  4. The change in entropy of the system for an adiabatic process in a closed system must be zero

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Correct Option: B,C,D

A container of volume $1{m}^{3}$ is divided into two equal parts by a partition. One part has an ideal diatomic gas at $300K$ and the other part has vacuum. The whole system is isolated from the surrounding. When the partition is removed, the gas expands to occupy the whole volume. Its temperature will be:

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. $300K$

  2. ${ 227.5 }^{ o }C$

  3. $455K$

  4. ${455}^{o}C$

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Correct Option: A