Chemistry

Equilibrium

Question:

What is the effect of:
(i) addition of H2 (ii) addition of CH3OH
(iii) removal of CO (iv) removal of  CH3OH
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-52

Answer:

(i) Equilibrium will be shifted in the forward direction.
(ii) Equilibrium will be shifted in the backward direction.
(iii) Equilibrium will be shifted in the backward direction.
(iv) Equilibrium will be shifted in the forward direction.

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Equilibrium

Q 1.

How does a catalyst affect the equilibrium constant?

Q 2.

State Ostwald’s dilution law.

Q 3.

The pH of0.005 M codeine (C18H21N03) solution is 9.95. Calculate the ionization constant and  PKb.

Q 4.

Define solubility product.

Q 5.

Conjugate acid of a weak base is always stronger. What will be the decreasing order of basic strength of the following conjugate bases?
OH, RO, ch3coo , cl

Q 6.

The pH of a sample of vinegar is 3.76. Calculate the concentration of hydrogen ion in it.

Q 7.

Match the following equilibria with the corresponding condition

Column I Column II
(i) Liquid⇌Vapour (a) Saturated solution
(ii) Solid ⇌Liquid (b) Boiling point
(iii) Solid ⇌Vapour (c) Sublimation point
(iv) Solute(s) ⇌Solute (solution) (d) Melting point ‘
    (e) Unsaturated solution

Q 8.

Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure bp increasing the volume?
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-45

Q 9.

pH of a solution of a strong acid is 5.0. What will be the pH of the solution obtained after diluting the given solution a 100 times?

Q 10.

Nitric oxide reacts with bromine and gives nitrosyl bromide as per reaction given below:
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-16
When 0.087 mole of NO and 0.0437 mole of Br2 are mixed in a closed container at constant temperature, 0.0518 mole of NOBr is obtained at equilibrium. Determine the compositions of the equilibrium mixture.

Q 11.

Hydrogen gas is obtained from the natural gas by partial oxidation with steam as per following endothermic reaction:
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-50
Write the expression for Kpfor the above reaction
How will the value of Kp and composition of equilibrium mixture be affected by:
(i) increasing the pressure, (ii) increasing the temperature, (iii) using a catalyst?

Q 12.

The concentration of hydrogen ions in a sample of soft drink is 3.8 x  10-3  M. What is the pH value?

Q 13.

State the law of mass action?

Q 14.

Which of the following reactions will get affected by increase in pressure ? Also mention whether the change will cause the reaction to go to the right or left direction.
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-46

Q 15.

Define ionic equilibrium.

Q 16.

Given the equilibrium  N2O4  (g) ——->2NO2 (g)     K=0.15 atm at 298 K
(a) What is Kp using pressure in torr?
(b) What is  Kc  using units of moles per litre.

 

Q 17.

(i) Define Le Chatelier’s principle.
(ii) Following reactions occur in a Blast furnace.
Fe203(s) + 3CO(g) ———–>2Fe(s) + 3CO2(g)
use Le chatelier’s principle to predict the direction of reaction when equilibrium mixture is disturbed by
(a) adding Fe203 (b) removing CO2 .
(c) removing CO.

Q 18.

Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction:
CH4(g) + H2O(g) ——> CO(g) + 3 H2(g)
(a) Write an expression for Kpfor the above reaction.
(b) How will the values of Kp and composition of equilibrium mixture be affected by (i) increasing the pressure (ii) increasing the temperature (iii) using a catalyst?

Q 19.

The value of Kc for the reaction
2HI(g) ⇌H2(g) + I2(g) is 1 x 10-4.  At a given time, the composition of reaction mixture is [HI] = 2 x 10-5 mol, [H2] = 1 x 10-5 mol and [I2] = 1 x 10-5 mol. In which direction will the reaction proceed?

Q 20.

A sample of HI (g) is placed in a flask at a pressure of 0.2 atm. At equilibrium partial pressure of HI (g) is 0.04 atm. What is Kp for the given equilibrium?
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-19

Q 21.

BF3 does not have proton but still acts as an acid and reacts with NH3. Why is it so? What type of bond is formed between the two?

Q 22.

A reaction between ammonia and boron trifluoride is given below:
:NH3 + BF3 →H3N : BF3
Identify the acid and base in this reaction. Which theory explains it? What is the hybridization of B and N in the reactants?

Q 23.

For the following equilibrium, K =6.3 x 1014  at 1000 K.  NO(g)+O3 —–>NO2(g) + O2(g)  Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is Kc for the reverse reaction ?

Q 24.

The species  H20, HCO3, HSO4 and NH3  can act both as Bronsted acid and base. For each case, give the corresponding conjugate acid and base.

Q 25.

The ionization constant of acetic acid is 1.74 x  10-5. Calculate the degree of dissociation of acetic acid in its 0.05 M solution. Calculate the concentration of acetate ions in the solution and its pH.

Q 26.

Write conjugate add and conjugate base of H2O?

Q 27.

Define common ion effect.  

Q 28.

The value of Kc for the reaction 2A——>B + C is 2 x 10-3. At a given time, the composition of reaction mixture is [A] = [B] = [C] = 3 x 10-4 M. In which direction the reaction will proceed?

Q 29.

PCl5, PCl3 and Cl2 are at equilibrium at 500 K and having concentration 1.59M PCl5 1.59M Cl2 and 1.41M PCl5. Calculate Kc for the reaction PCl5———>PC13+ Cl2

Q 30.

At a particular temperature and atmospheric pressure, the solid and liquid phases of a pure substance can exist in equilibrium. Which of the following term defines this temperature? .
(a) Normal melting point
(b) Equilibrium temperature
(c) Boiling point
(d) Freezing point

Q 31.

The aqueous solution of sugar does not conduct electricity. However, when sodium chloride is added to water, it conducts electricity. How will you explain this statement on the basis of ionization and how is it affected by concentration of sodium chloride?

Q 32.

A sparingly soluble salt gets precipitated only when the product of concentration of its ions in the solution (Qsp) becomes greater than its solubility product. If the solubility of BaS04 in water is 8 x 10-4 mol dm-3, calculate its solubility in 0.01 mol dm-3 of H2S04.

Q 33.

A liquid is in equilibrium with its vapours in a sealed container at a fixed temperature. The volume of the container is suddenly increased, (i) What is the initial effect of the change on the vapour pressure? (ii) How do the rates of evaporation and condensation change initially? (iii) What happens when equilibrium is restored finally and what will be the final vapour pressure?

Q 34.

ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-17

Q 35.

ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-37

Q 36.

Calculate (a) ∆G and (b) the equilibrium constant for the formation of N02 from NO and 02 at 298 K
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-43

Q 37.

Write the conjugate acids for the following Bronsted bases:
NH2, NH3 and HCOO

Q 38.

The ionization constant of HF, HCOOH and HCN at 298 K are is 6.8 x 10-4 , 1.8 x 10-4 and 4.8 x 10-9  respectively, Calculate the ionization constant of the corresponding conjugate base.

Q 39.

The degree of ionization of a 0.1 M bromoacetic acid solution is 0.132. Calculate the pH of the solution and the PKa  of bromoacetic acid.

Q 40.

What is meant by reaction quotient?

Q 41.

How does common ion affect the solubility of electrolyte?

Q 42.

S032-is Bronsted base or acid and why?

Q 43.

(i) Point out the differences between ionic product and solubility product.
(ii) The solubility of AgCl in water at 298 K is 1.06 x 10-5  mole per litre. Calculate its solubility product at this temperature.

Q 44.

Q 45.

For the reaction N204(g) ⇌2N02(g), the value of K is 50 at 400 K and 1700 at 500 K. Which of the following options is correct?
(a) The reaction is endothermic.
(b) The reaction is exothermic.
(c) If NO2(g) and N204(g) are mixed 400 K at partial pressures 20 bar and 2 bar respectively, more N204(g) will be formed.
(d) The entropy of the system increases.

Q 46.

The ionization of hydrochloric acid in water is given below:
HCl(aq) + H20(l) ⇌H30 + (aq) +Cl(aq)
Label two conjugate acid-base pairs in this ionization.

Q 47.

Ionization constant of a weak base MOH, is given by the expression

ncert-exemplar-problems-class-11-chemistry-chapter-7-equilibrium-9
Values of ionization constant of some weak bases at a particular temperature are given below:

Base Dimethylamine Urea Pyridine Ammonia
  5.4 x 10-4 1.3 x 10-14 1.77 x lO-9 1.77 xlO-5

Arrange the bases in decreasing order of the extent of their ionization at equilibrium. Which of the above base is the strongest?

Q 48.

pH of 0.08 mol dm3HOC1 solution is 2.85. Calculate its ionization constant.

Q 49.

Calculate the pH of a solution formed by mixing equal volumes of two solutions A and B of a strong acid having pH = 6 and pH = 4 respectively.

Q 50.

The solubility product of Al(OH)3 is 2.7 x 10-11. Calculate its solubility in gL and also find out pH of this solution. (Atomic mass of A1 = 27 u).