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Chemistry Test 179
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Chemistry Test 179
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  • Question 1/10
    4 / -1

    Consider the following reaction:

    N2O4(g) ⇋ 2NO2(g); ΔH0 = +58 kJ

    For each of the following cases (a, b), the direction in which the equilibrium shifts is:

    (a) Temperature is decreased.

    (b) Pressure is increased by adding N2 at constant T.

    Solutions

    (a) temp↓ ⇒ Backward shift as it is an endothermic reaction

    (b) As 'N2' will not react with both N2O4 and NO2, there will be no change in equilibria.

     

  • Question 2/10
    4 / -1

    For the reaction

    Fe2N(s) + 3/2 H2(g) ⇋ 2Fe(s) + NH3(g),

    Solutions

    Kp = K(RT)Δng as Δng = 1 – 3/2 = –1/2

    Kp = K(RT)–1/2

    Kc = K(RT)1/2

     

  • Question 3/10
    4 / -1

    Solutions

     

  • Question 4/10
    4 / -1

    The first and second dissociation constants of an acid H2A are 1.0 × 10-5 and 5.0 × 10-10 respectively.

    The overall dissociation constant of the acid will be:

    Solutions

     

  • Question 5/10
    4 / -1

    What volume of 0.2 M NH4Cl solution should be added to 100 ml of 0.1 M NH4OH solution to produce a buffer solution of pH = 8.7 ?

    Given : pKb of NH4OH = 4.7 ; log 2 = 0.3

    Solutions

     

  • Question 6/10
    4 / -1

    How many gm of solid NaOH must be added to 100 ml of a buffer solution which is 0.1 M each w.r.t. Acid HA and salt Na+ A- to make the pH of solution 5.5. Given pKa(HA) = 5 (Use antilog (0.5)= 3.16)

    Solutions

     

  • Question 7/10
    4 / -1

    100 mL of 0.1 M HCl is taken in a beaker and to it 100 mL of 0.1 M NaOH is added in steps of 2 mL and the pH is continuously measured.

    Which of the following graphs correctly depicts the change in pH?

    Solutions

    For titration between HCl and NaOH, pH at equivalence point is found to be 7 and the graph should depict a sharp increase in the pH value at the equivalence point.

    Hence, option (1) is correct.

     

  • Question 8/10
    4 / -1

    How many litres of water must be added to 1 litre of an aqueous solution of HCl with pH = 1 to create an aqueous solution with pH = 2?

    Solutions

    Initial pH = 1, i.e. [H+] = 0.1 mole/litre

    New pH = 2, i.e. [H+] = 0.01 mole/litre

    In case of dilution: M1V1 = M2V2

    0.1 × 1 = 0.01 × V2

    V2 = 10 litres

    Volume of water added = 9 litres

     

  • Question 9/10
    4 / -1

    Which one of the following solutions has the maximum pH value?

    Solutions

    Sodium acetate solution (0.2 M NaC2H3Osolution) will be alkaline and thus, will have the maximum pH value.

     

  • Question 10/10
    4 / -1

    The pH of 0.1 M NH4OH (Kb = 1.8 × 10–5 M) at 25°C is

    Solutions

     

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