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1)

Thermal decomposition of gaseous X2, to gaseous X at 298 K takes place according to the following equation

X2(g)2X(g)

The standard reaction Gibbs energy, ΔrG0, of this reaction is positive. At the start of the reaction, there is one mole of X2 and no X. As the reaction proceeds, the number of moles of X formed is given by β. Thus, βequilibrium is the number of moles of X formed at equilibrium. The reaction is carried out at a constant total pressure of 2 bar. Consider the gases to behave ideally. (Given, R = 0.083 L bar K-1 mol-1)

The incorrect  statement among the following reaction , is


A) Decrease in the total pressure will result in the formation of more moles of gaseous X

B) At the start of the reaction , dissociation of gaseous X2 takes place spontaneously

C) βequilibrium=0.7

D) KC<1

Answer:

Option C

Explanation:

a)          Kp=4px2(4x2)=px2(4>>>x)

xα1p

If p decreases, x increases. Equilibrium is shifted in the forward  side. Thus, statement(a) is correct

(b)       At the start of the reaction , Q=0 where , Q is the reaction quotient

   G=G0+2.303RTlogQ

   since   G0>0  , thus  G is -ve

Hence, dissociation take place spontaneously,

 Thus (b) is correct

 (c) If we use x= 0.7 and p=2 bar,

  then  Kp=4×2(0.7)2[4(0.7)2]=1.16>1

Thus, (c) is incorrect

(d) At equilibium, G=0

      G0=2.303RTlogKp

Since , G0=+ve

Hence,Kp<1,KC=Kp(RT)

Then KC<1 , Thus (d) is correct