Tag: equilibrium in physical processes

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Questions Related to equilibrium in physical processes

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

At 373 K, steam and water are in equilibrium and $\Delta H$ = 40.98 kJ $mol^{-1}$.What will be  $\Delta S$ fro conversion of water into steam?
$H _2O _{(l)} \rightarrow H _2O _{(g)}$

  1. 109.8 J $K^{-1}mol^{-1}$
  2. 31 J $K^{-1}mol^{-1}$
  3. 21.98 J $K^{-1}mol^{-1}$
  4. 326 J $K^{-1}mol^{-1}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The given reaction is :-

${ H } _{ 2 }O\left( l \right) \longrightarrow { H } _{ 2 }O\left( g \right) $
So, we have
       $\triangle Svap=\dfrac { \triangle Hvap }{ Tb } $
                     $=\dfrac { 40.98\times 1000 }{ 373 } =109.8{ JK }^{ -1 }{ mol }^{ -1 }$

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

At what temperature liquid water will be in equilibrium with water vapour?
$\Delta H _{vap} = 40.73 \ kJ \ mol^{-1}$, $\Delta S _{vap} = 0.109 \ kJ \ K^{-1} \ mol^{-1}$, 

  1. 282.4 K

  2. 373.6 K

  3. 100 K

  4. 400 K
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The given reaction is :-

               ${ H } _{ 2 }O\left( l \right) \rightleftharpoons { H } _{ 2 }O\left( g \right) $
Now, at equilibrium, $\triangle G=0$
Now, from fibb's free energy change equation
         $\triangle G=\triangle H-T\triangle S$
$\Rightarrow \quad \triangle H=T\triangle S$
$\Rightarrow \quad T=\dfrac { \triangle H }{ \triangle S } =\dfrac { 40.73 }{ 0.1079 } =373.6K$
$\left( \because \triangle Hrap=40.73KJ/mol,\quad \triangle Srap=0.109KJ{ K }^{ -1 }{ mol }^{ -1 } \right) $

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

Which of the following represent physical equlibrium?

  1. Dissolution of solid $KI$ in water
  2. Sublimation of $NH _4Cl$

  3. Evaporation of dry ice in a closed container

  4. Condesation of water vapours
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Physical equilibrium involves a physical process where the rate of the forward process equals the rate of the reverse process. Dissolution of a solid in a saturated solution is a classic example of physical equilibrium.

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

A yellow precipitate obatined in II group of the equilibrium analysis was soluble in aq. $NaOH$ and insoluble in dil. $HNO _3$. This shows the presence of:

  1. $Tin$
  2. $Antimony$
  3. $Arsenic$
  4. $Cadmium$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In qualitative analysis, Tin (Sn) sulfides (SnS2) are soluble in yellow ammonium sulfide or NaOH, forming a soluble complex, and precipitate upon acidification with dil. HNO3 or HCl.

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

Which of the following statements is incorrect ?

  1. In equilibrium mixture of ice water kept in perfectly insulated flask mass of ice and water does not change with time .

  2. The intensity of red colour increase when oxalic acid is added to a solution containing iron (III) nitrate and potassium thioyanate .

  3. On addition of catalyst equilibrium constant value is not affected .
  4. Equilibrium constant for a reaction with negative $\triangle H$ value decreases as the temperature increases .
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Adding oxalic acid to a solution containing iron(III) nitrate and potassium thiocyanate forms stable Fe-oxalate complexes, which consumes free Fe3+ ions. According to Le Chatelier's principle, this shifts the equilibrium for the formation of the red iron-thiocyanate complex backward, causing the red color to fade, not increase. Thus, statement B is incorrect.

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

Two flasks A and B of an equal volume containing 1 mole and 2 moles of O$ 3$ respectively are heated to the same temperature. When the reaction $2O _3 \rightleftharpoons 3O _2$ practically stops, then both the flasks shall have __________.

  1. the same ratio: $[O _2]/[O _3]$
  2. the same ratio: $[O _2]^{3/2}/[O _3]$
  3. only $O _2$

  4. the same time to reach equilibrium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For the given reaction,
$K _c = \displaystyle \frac{[O _2]^3}{[O _3]^2}= constant$     so  $\displaystyle \sqrt{K _c} = \frac{[O _2]^{3/2}}{[O _3]} = constant$
Same for both containers. Kc won't change as flasks are heated to same temperature. 

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

Which of the following is not a general characteristic of equilibrium involving physical processes ?

  1. equilibrium is possible only in a closed system at a given temperature .

  2. all measurable properties of the system remain constant .

  3. all the physical processes stop at equilibrium.

  4. the opposing processes occur at the same ratio and there is dynamic but stable condition .
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Equilibrium is a dynamic process, not a static one. Even at equilibrium, the forward and backward processes continue to occur at the same rate; they do not stop.