Sunday, August 5, 2012

Ten Year of Chemical Equilibrium



 Prepared by:
Lecturer  S.Fayyaz Hussain

City Of Knowledge
              (Science Campus)
Add: 24/2 Sheet # 10 Model Colony Near Model Colony Karachi, Pakistan
 Ph : +9221-35449369, +92312-5449369

Ten years
                                                           
Chapter # 6                                                                          Chemical Equilibrium                         

 1992


Q.5 ( c)            In chemical reaction
                        PCl5      ↔    PCl3                 + Cl2
Calculate the mole of chlorine produce at equilibrium when 1 mole of PCl5 is heated at 2500c in a vessel of capacity 10 dm3 (Kc for the reaction is 0 .041)
Q.6 ( b)            Discuss the conditions of concentration , pressure and temperature in the presence of catalyst for maximum  yield  of ammonia in the reaction  
                        N2    + 3H2   ↔ 2NH3        ∆H  =( - ve )
Q.6 ( c)            How is the equilibrium constant value used to predict the extent of reaction ? 

Q.7 ( a)            Explain the term “ Solubility Product” . What is the criterion for the precipitation from a solution? 
Illustrate by calculation whether PbCrO4 wouid precipitate out if 100 cm3 of 2.5* 10-4 M Pb(NO3)solution is mixed with 300 cm3 solution of KCrO4 concentration 1.5* 10-8 M ( Ksp =1.8*10-14 )




1993


Q. .1 ( a)          explain the following term
Reversible reaction             Equilibrium constant
Solubility product
Q.4 (a)             write short note
                        Law of Mass Action

1994


Q.4 ( c)            For reaction
                        N  +  3H2 ↔= 2NH3
The equilibrium mixture contain  .25 M nitrogen  .15 M  hydrogen gas at 250 c. Calculate the concentration of NH3 gas when Kc =9.6 .The volume of the container is 1dm3.   

1995


Q.6 (a) state and explain Le Chatlelier principle
(b)            Discuss the condition to increase the yield of NH3 in Haber’s process
( c)           At equilibrium a 12 dm3 falsk contain 0.21 mole of PCl5 0.32 mole of PCl3 and 0.32 mole Cl2 at 2500 c find the value of Kc for reaction    
                                     PCl5      ↔    PCl3                 + Cl2
Q.7 (a) Define solubility product and solubility
(b)            Should AgCl precipitate form a solution prepared mixing of 400 cm3 0.1M NaCl and 600 cm3 0.03M AgNO3 ?(Ksp of AgCl=1.6* 10-10 mol/ dm3 .
             
1995

Q.5 (a) state and explain Law of Mass Action .
       (b) For the reaction    H2   +   I2 ↔  2HI
Kc is     49 . Calculate the concentration of HI at equilibrium when initial one mole of H2 is mixed with one more of I2 in one liter flask .  
( c)           What is Common ion Effect ? How is it applied in qualitative analysis ?

Q.7(d)             How is Kc used to predict the direction of a reversible reaction ?
(e)            Kc for areaction is  0.0194 and the calculated ratio of the concentration  of the reactants is 0.0116 . Predict the direction of the reaction              


1997

Q.8 (a) State the following :
                        Law of Mass Action                           le- Chatelier principle
(b)          Predict the effect of change  of temperature and effect pressure on following equilibrium mixture : 
                        N2   +   3H2    ↔   2NH3     +Heat
                        H2   +    I2   +     Heat       ↔   2HI
      (c ) Explain Solubility Product .
      (d)             Should AgCl precipitate from a solution prepared by mixing  400 cm3 0.1 M Nacl  and 600 cm3 of 0.03 M solution of AgNO3?
                        ( Kc for AgCl =1.6  * 10-10 mol/dm3)

1998

Q.7 (a)             state and explain Law of Mass Action and derive the  equilibrium constant expression for the general equilibrium reaction :
                        mA    + nB     ↔    xC       +   yD
       (b)             the equilibrium constant expression for  a gaseous equilibrium     

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