Saturday, February 4, 2012

Chemical Equilibirium (Subjectives and Problems)


Chemical Equilibirium
Subjective Question
Q.1              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  = Negative

Q.2              How is the equilibrium constant value used to predict the extent of reaction ? 

Q.3              Explain the term “ Solubility Product” . What is the criterion for the precipitation from a solution?

Q. 4             Explain the following term
i )Reversible reaction  ii)   Equilibrium constant
 iii) Solubility product iv) Law of Mass Action
 v) Le- Chatelier principle

Q.5              State and explain Law of Mass Action.

Q.6              State and explain Le-Chatlelier principle

Q.7              Discuss the condition to increase the yield of NH3 in Haber’s process.

Q.8              Differntiate solubility product with solubility.

Q.9              How is Kc used to predict the direction of a reversible reaction?
                   
Q.10            Predict the effect of change  of temperature and effect pressure on following equilibrium mixture : 
                    H2   +    I2   +     Heat       ↔   2HI

Q.11State and explain Law of Mass Action and derive the  equilibrium constant expression for the general equilibrium reaction :
                    mA    + nB     ↔    xC       +   yD


Problems

 Q.1            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.2               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.  

Q.3              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.4              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 mol2/ dm6 )

Q.5              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 .
                         
Q.6              Kc for a reaction is 0.0194 and the calculated ratio of the concentration  of the reactants is 0.0116 . Predict the direction of the reaction.
Q.7              Will PbCrO4 precipitate from a solution prepared by mixing 200 cm3 of 2.5 x 10-4 M Pb(NO3)2 and 600 cm3 of 1.5 x 10-8 M of  K2CrO4?  (K(sp) of PbCrO4 = 1.5 x 10-14 )
Q.8              For the reaction 2Hl ↔ H2 + l2, one mole of Hl is introduced into a vessel at constant  temperature. Calculate the number of moles of l2 when the equilibrium is reached(Kc =0.0156).
Q.9              Define Solubility product (Ksp). Find the Ksp of CaCO3, the solubility of CaCO3 is 0.001 g / dm3
                    CaCO3                  ↔      Ca2+ + CO32-
Q.10            The equilibrium constant for the reaction    N2 + O2 ↔ 2NO
at 20000C is 0.1. Calculate the equilibrium concentration of the reactants and product when the initial concentration of N2 and O2 are 10 mole/dm3


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