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
N2 + 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
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—
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-
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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