Equilibrium quiz

At equilibrium, the rate of the forward reaction is:

For the reaction H2 + I2 <-> 2HI, the relation between Kp and Kc is:

The pH of a 0.0001 M HCl solution is:

Which of these is a Lewis acid?

The ionic product of water at 298 K is:

Adding a catalyst to a system at equilibrium:

For an exothermic reaction, raising the temperature:

The conjugate acid of NH3 is:

Which salt gives a basic solution on hydrolysis?

If Q < K, the reaction will proceed:

Why is chemical equilibrium called dynamic? (2 marks)

What is a heterogeneous equilibrium? Give an example. (2 marks)

What is the effect of increasing pressure on 2SO2 + O2 <-> 2SO3? (2 marks)

What does the magnitude of K tell us about a reaction? (2 marks)

Distinguish between strong and weak electrolytes. (2 marks)

What is the relation between Ka and Kb for a conjugate acid-base pair? (2 marks)

Why is the pH of pure water 7 at 298 K? (2 marks)

What is the common ion effect? (2 marks)

Define solubility product. (2 marks)

Why is an aqueous solution of NH4Cl acidic? (2 marks)

Calculate the pH of a solution with [H+] = 2.0 x 10^-4 M (log 2 = 0.30). (3 marks)

The Ka of formic acid is 1.8 x 10^-4. Calculate the Kb of its conjugate base at 298 K. (3 marks)

For CaCO3(s) <-> CaO(s) + CO2(g), Kp = 2.0 x 10^-2 bar at a certain temperature. Calculate the pressure of CO2 at equilibrium. (3 marks)

Calculate the hydroxide ion concentration in a solution of pH 9. (3 marks)

The Ksp of BaSO4 is 1.1 x 10^-10. Calculate its molar solubility. (3 marks)

Read the passage and answer the questions. Ammonia is manufactured by the Haber process: N2(g) + 3H2(g) <-> 2NH3(g), delta H = -92.4 kJ/mol. The process is carried out at about 500 degrees C and 200 atm pressure using an iron catalyst. The ammonia formed is removed continuously. (i) Why is high pressure used? (ii) Why is a moderate temperature used instead of a low one? (iii) Why is ammonia removed continuously? (5 marks)

Read the passage and answer the questions. The pH of blood is maintained at about 7.4 by buffer systems such as carbonic acid and bicarbonate ions. A change of even 0.5 units can be fatal. Similarly, many reactions in industry need a constant pH. (i) What is a buffer? (ii) How does blood resist the addition of acid? (iii) Calculate [H+] in blood at pH 7.4 (antilog of -7.4 = 3.98 x 10^-8). (5 marks)

Read the passage and answer the questions. A student placed water in a closed vessel at room temperature. Initially, the water level fell, but after some time it became constant. The pressure in the vessel also became constant. (i) Why did the level become constant? (ii) What is the constant pressure called? (iii) Is this a physical or chemical equilibrium? (5 marks)

Read the passage and answer the questions. According to the Bronsted-Lowry theory, an acid is a proton donor and a base is a proton acceptor. When HCl dissolves in water, it donates a proton to water to form H3O+ and Cl-. In NH3 + H2O <-> NH4+ + OH-, water acts as an acid. (i) Identify the conjugate pairs in the second reaction. (ii) Why is water called amphoteric? (iii) Why is Cl- a very weak base? (5 marks)

Read the passage and answer the questions. Silver chloride is a sparingly soluble salt. In a saturated solution, AgCl(s) <-> Ag+(aq) + Cl-(aq) and Ksp = [Ag+][Cl-]. When common salt is added to this solution, a white precipitate appears. (i) Write the expression for Ksp. (ii) Why does a precipitate form when NaCl is added? (iii) State the condition for precipitation in terms of the ionic product. (5 marks)

Explain equilibrium in physical processes with examples. State the general characteristics of equilibria. (6 marks)

State the law of chemical equilibrium. Derive the relation between Kp and Kc. Explain homogeneous and heterogeneous equilibria with examples. (6 marks)

State Le Chatelier's principle. Explain the effect of concentration, pressure, temperature, catalyst and inert gas on equilibrium with examples. (6 marks)

Explain the Arrhenius, Bronsted-Lowry and Lewis concepts of acids and bases. Define pH and explain the ionisation of weak acids and bases. (6 marks)

Explain the common ion effect, hydrolysis of salts, buffer solutions and solubility product with examples and calculations. (6 marks)