Chemistry

Equilibrium

Question:

At 1127 K and 1 atmosphere pressure, a gaseous mixture of CO and C02 in equilibrium with solid carbon has 90.55% CO by mass.
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-41
Calculate Kc for the reaction at the above temperature.

Answer:

ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-42

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Equilibrium

Q 1.

How does a catalyst affect the equilibrium constant?

Q 2.

State Ostwald’s dilution law.

Q 3.

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 4.

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

Q 5.

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

Q 6.

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 7.

Which of the following are Lewis Acids?
H2O,BF3, H+ and NH4+,

Q 8.

What is meant by ionic product of water (kw)?

Q 9.

Write conjugate add and conjugate base of H2O?

Q 10.

S032-is Bronsted base or acid and why?

Q 11.

Explain why pure liquids and solids can be ignored while writing the value of equilibrium constants.

Q 12.

What is meant by equilibrium ?

Q 13.

What is the equilibrium concentration of each of the substances in the equilibrium when the initial concentration of ICl was 0.78 M?
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-27

Q 14.

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 15.

What is meant by conjugate acid-base pair? Find the conjugate acid/base for the following species:  HNO2, CH, HClO4 , OH, CO32-, S2-

Q 16.

The ionization constant of phenol is 1.0 x 10-10. What is the concentration of phenolate ion in 0.05 M solution of phenol? What will be its degree of ionization if the solution is also 0.01 M in sodium phenolate?

Q 17.

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 18.

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 19.

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 20.

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

Q 21.

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 22.

Define ionic equilibrium.

Q 23.

Give two characteristics of a buffer solution.

Q 24.

Write the equilibrium constant (Kc) expression for the following reactions.
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-5

Q 25.

Q 26.

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

Q 27.

One of the reactions that takes place in producing steel from iron ore is the reduction of iron
(II) oxide by carbon monoxide to give iron metal and C02
FeO(s) + CO(g) ———>Fe(s) + C02(g) ; Kp = 0.265 atm at 1050 K
What are the equilibrium partial pressures of CO and C02  at 1050 K if the initial pressures are:  PCO = 1.4 atm and PCO2 = 0.80 atm?

Q 28.

Bromine monochloride (BrCl  ) decomposes into bromine and chlorine and reaches the equilibrium:
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-39
The value of Kc is 32 at 500 K. If initially pure BrCl   is present at a concentration of 3.3 x10-3mol L-1what is its molar concentration in the mixture at equilibrium?

Q 29.

Define solubility product.

Q 30.

What is basic buffer?

Q 31.

In the reaction A + B———> C + D, what will happen to the equilibrium if concentration of A is increased?
(b) The equilibrium constant for a reaction is 2 x 10-23    at 25 °C and 2 x 10-2 at 50 °C. Is the reaction endothermic or exothermic?
(c) Mention at least three ways by which the concentration of S03 can be increased in the following reaction in a state of equilibrium.

Q 32.

The ionization constant of an acid, Ka is the measure of strength of an acid. The Ka values of acetic acid, hypochlorous acid and formic acid are 1.74 x 10-5, 3.0 x 10-8 and 1.8 x 10-4 Which of the following orders of pH of 0.1 mol dm-3 solutions of these acids is correct?
(a) acetic acid > hypochlorous acid > formic acid
(b) hypochlorous acid > acetic acid > formic acid
(c) formic acid > hypochlorous acid > acetic acid
(d) formic acid > acetic acid > hypochlorous acid

Q 33.

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 34.

For the reaction: N2(g) + 3H2(g) ⇌2NH3(g) equilibrium constant,

ncert-exemplar-problems-class-11-chemistry-chapter-7-equilibrium-18
Some reactions are written below in Column I and their equilibrium constants in terms of Kc are written in Column II. Match the following reactions with the corresponding equilibrium constant.

ncert-exemplar-problems-class-11-chemistry-chapter-7-equilibrium-19

Q 35.

At 473 K, the equilibrium constant Kc for the decomposition of phosphorus pentachloride (PCl5) is 8.3 x 10-3 . if decomposition proceeds as:
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-53
(a) Write an expression for Kc for the reaction
(b) What is the value of Kc for the reverse reaction at the same temperature.
(c) What would be the effect on Kc if
(i) More of PCl5is added (ii) Temperature is increased.

Q 36.

ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-61

Q 37.

Classify the following species into Lewis acids and Lewis bases and show how these can act as Lewis acid/Lewis base?
(a) OHions (b) F(c) H+ (d) BCl3

Q 38.

Define common ion effect.  

Q 39.

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 40.

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 41.

It has been found that the pH of a 0.01 M solution of an organic acid is 4.15. Calculate the concentration of the anion, the ionization constant of the acid and its  PKa.

Q 42.

State the law of mass action?

Q 43.

The values of Ksp of two sparingly soluble salts  Ni(OH)2  and AgCN are 2.0 x 10-15    and 6 x 10-17    respectively. Which salt is more soluble? Explain.

Q 44.

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 45.

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 46.

Write the expression for the equilibrium constant for each of the following reactions
ncert-solutions-for-class-11-chemistry-chapter-7-equilibrium-6

Q 47.

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 48.

What will be the conjugate bases for the Bronsted acids?HF, H2S04 and H2C03?

Q 49.

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 50.

How does common ion affect the solubility of electrolyte?