Phase Equilibria - Physical Chemistry - Chemistry Previous Year Questions

1

2008 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2008

For a one component system, the maximum number of phases that can coexist at equilibrium is

A

3

B

2

C

1

D

4

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2

2009 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2009

The number of degrees of freedom of a system consisting of solid sucrose in equilibrium with an aqueous solution of sucrose is

A

0

B

1

C

2

D

3

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3

2011 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2011

On the pressure-temperature diagram for a one-component system, the point where the solid-liquid and the liquid-gas curves intersect is

A

triple point

B

critical point

C

melting point

D

boiling point

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4

2011 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2011

According to the Ehrenfest classification of phase transitions, the above diagram refers to

A

Zeroth order phase transition

B

First order phase transition

C

Second order phase transition

D

λ transition

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5

2012 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2012

Consider the phase diagram given below.
[Image of phase diagram]
At the intersection point Q the phases that are in equilibrium are

A

solid A, solid B and solid AB₂

B

solid A, solid AB₂ and liquid

C

solid B, solid AB₂ and liquid

D

solid A, solid B, solid AB₂ and liquid

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6

2013 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2013

The change in enthalpy when 3 mol of liquid benzene transforms to the vapor state at its boiling temperature (80 °C) and at 1 bar pressure is __________ kJ.

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7

2014 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2014

Of the following plots, the correct representation of chemical potential (μ) against absolute temperature (T) for a pure substance is (s, l and g denote solid, liquid and gas phases, respectively)

A

Graph A

B

Graph B

C

Graph C

D

Graph D

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8

2014 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2014

The enthalpy of fusion of ice at 273 K is 6.01 kJ mol^–1 and the enthalpy of vaporization of water at 273 K is 44.83 kJ mol^–1. The enthalpy of sublimation (in kJ mol^–1) of ice at 273 K, is ______________

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9

2016 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2016

At 1 bar and 298 K, for the process A(s) → A(l), the ΔG is 200 J mol⁻¹ and the ΔVₘ is −2 × 10⁻⁶ m³ mol⁻¹. The minimum pressure, in bar, at which the process becomes spontaneous at 298 K is ________. (1 bar = 10⁵ Pa)

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10

2016 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2016

The temperature-composition (\(T\)-\(x\)) phase diagram of the two-component system made of X and Y is given below. At a temperature of 288 K and starting at the point P, Y is added until the composition reaches S. Which of the following statements is NOT TRUE? [Phase diagram]

A

At P, the solid and liquid are present in almost equal proportions.

B

At Q, the system is all liquid.

C

At S, the system has more solid than liquid.

D

At R, the liquid is pure X.

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11

2019 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2019

The normal boiling point of a compound (X) is 350 K (heat of vaporization, Δ_vapH = 30 kJ mol⁻¹). The pressure required to boil 'X' at 300 K is ______ Torr. (Round off to two decimal places)
(Ignore the temperature variation of Δ_vapH; Gas constant R = 8.31 J mol⁻¹ K⁻¹ and 1 atm = 760 Torr)

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12

2024 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2024

The following figure shows an experimental liquid-liquid phase diagram of phenol and water at the vapor pressure of the system. The total amount of phenol and water (in mol) present in the phenol-rich phase when 5 mol of water was shaken with 5 mol of phenol at 40 °C is ____.
(rounded off to one decimal place)

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13

2025 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2025

The expressions for the vapour pressure of solid (p₁) and vapour pressure of liquid (p₂) phases of a pure substance, respectively, are
ln p₁ = −2000/T + 5 and ln p₂ = −4000/T + 10
The triple point temperature of this substance is ____ K (in integer).

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14

2007 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2007

The specific volume of liquid water is 1.0001 mL g^-1 and that of ice is 1.0907 mL g^-1 at 0°C. If the heat of fusion of ice at this temperature is 333.88 J g^-1, the rate of change of melting point of ice with pressure in deg atm^-1 will be

A

-0.0075

B

0.0075

C

0.075

D

-0.075

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15

2007 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2007

The number of degrees of freedom for a system consisting of NaCl(s), Na⁺(aq) and Cl^-(aq) at equilibrium is

A

2

B

3

C

4

D

5

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16

2010 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2010

Sulfur can exist in four phases. The possible number of triple points is

A

1

B

2

C

3

D

4

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17

2010 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2010

Based on the above diagram:

A

A represents the change in chemical potential as a function of temperature for the solid phase, B for the liquid and C for the gas

B

A represents the change in chemical potential as a function of temperature for the liquid phase, B for the gas and C for the solid

C

A represents the change in chemical potential as a function of temperature for the gas phase, B for the liquid and C for the solid

D

A represents the change in chemical potential as a function of temperature for the gas phase, B for solid and C for the liquid

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18

2010 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2010

From the same diagram

A

D represents boiling point, E sublimation point and F melting point

B

E represents boiling point, D sublimation point and F melting point

C

E represents melting point, F sublimation point and D boiling point

D

D represents melting point, F boiling point and E sublimation point

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19

2015 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2015

A liquid has vapor pressure of \(2.02 \times 10^5 N m^{-2}\) at 293 K and heat of vaporization of \(41 kJ mol^{-1}\). The boiling point of the liquid (in Kelvin) is ____________________

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20

2017 · Chemistry · Physical Chemistry · Phase Equilibria

Chemistry (CY) 2017

m₁ and m₂ are the slopes (dP/dT) of the solid-liquid equilibrium lines in the P-T phase diagrams of H₂O and CO₂, respectively. For P < 10 atm, the values of m₁ and m₂ are

A

m₁ > 0 and m₂ > 0

B

m₁ > 0 and m₂ < 0

C

m₁ < 0 and m₂ < 0

D

m₁ < 0 and m₂ > 0

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