Sunday, August 5, 2012

Assignments of Chemical Equilibrium


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.11           State 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

Q. 11          5 moles of acetic acid and 1.5 moles of ethyl alcohol were reacted at a certain temperature. At equilibrium, 1 mole of ethyl acetate was present in 1 dm3 of the equilibrium mixture. Calculate the equilibrium constant Kc.

CH3COOH + C2H5OH                              CH3COOC2H5 + H2O
Q.12           6.0 gm of hydrogen and 1016gm of iodine were heated in a sealed tube at a temperature, at which Kc is 50. The volume of the tube is 1 dm3. Calculate the concentration of HI.

H2 + I2                           2HI
Q.13           At a certain temperature, an equilibrium mixture contains 0.4 mole H2, 0.4 mole I2 and 1 mole of HI. The volume of the reacting vessel is 4 dm3. Find out the equilibrium constant  Kc.
H2 + I2                           2HI
Q.14           3 moles of A and 2 moles of B are mixed in a 4dm3 flask, at a certain temperature. The following reaction occurs.
3A + 2B                  4C
                   At equilibrium the flask contains 1 mole of B. Find the equilibrium constant Kc.
Q.15           At a certain temperature, 0.205 mole of H2 and 0.319 mole of I2 were reacted. The equilibrium mixture contains 0.314 mole of I2. Calculate the kc.

H2 + I2                           2HI
Q.16           The Kc for the reaction A + B                  C + D  is 1/3   . How many moles of A  must be mixed with 3 moles of  B to yield at equilibrium  2 moles of C and D each. The volume of the vessel is 2 dm3.
Q.17           What is the solubility of lead chromate in moles/dm3 at 25°C. The solubility product is 1.8 x 10-14.

PbCrO4 ↔ Pb++  + CrO2—
Q.18           The solubility of Mg(OH)2 at 25°C is 0.00764 gm/dm3. What is the solubility product of Mg(OH)2?

Mg(OH)2 ↔ Mg++ + 2OH-
Q.19           Find the solubility of AgCl in gm/dm3, when the solubility product is 1.25 x 10-10.
Q.20           Calculate the solubility product of BaSO4. The solubility of the salt is 1.0 x 10-5 mol/dm3.
Q.21           Calculate the solubility product of BaSO4 is 9.0 x 10-3 gm/dm3. Find its solubility product.
Q.22           Predict whether there will be any precipitate formation by mixing 30cm3 of 0.01M NaCl with 60cm3 of 0.01M AgNO3 solution. Ksp of AgCl is 1.5 x 10-10.
Q.23           A saturated solution of calcium fluoride was found to contain 0.0168 gm/dm3 of solute at 25°C. Calculate the Ksp for CaF2.
Q.24           A saturated solution of BaF2 at 25°C is 0.006M. Calculate Ksp of the salt.
Q.25           At a certain temperature the equilibrium mixture for the reaction    A + B                       2C
contains 2 moles A , 3 moles of B and 5 moles of C. Find the Kc for the reaction.

 For the reaction     2A                     B + C equilibrium constant Kc is 1. If we start with 6 moles of A, how many moles of B will be formed.


 20 moles of SO2 and 10 moles of O2 are taken in a 20 dm3 flask. If  at  equilibrium 5 moles of SO3 are formed. Calculate Kc.

2SO2 + O2             2SO3

 a ) When 1 mole of pure C2H5OH is mixed with 1 mole of CH3COOH at room temperature, the equilibrium mixture contains 2/3 mole of ester and water each. · What will be the Kc?
CH3COOH + C2H5OH                               CH3COOC2H5 + H2O
 b )  How many moles of ester are formed at equilibrium when 3 moles of C2H5OH are mixed with 1 mole of CH3COOH?

CH3COOH + C2H5OH                               CH3COOC2H5 + H2O

 PCl5              PCl3 + Cl2. Calculate the number of moles of Cl2 produced at equilibrium when 1 mole of PCl5 is heated at 250°C in a vessel having capacity of 10dm3. At 250°C, Kc is 0.041.

When 2.94 moles of iodine and 8.1 moles of Hydrogen were mixed and heated at 444°C and at constant volume, until the equilibrium was established. 5.64 moles of HI were formed. Calculate the value of Kc.
H2 + I2                           2HI


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