Chapter 7

An element which can exist as a positive ion in acidic solution and also as a negative ion in basic solution is said to be ...............

\(0.15\) mole of \(\mathrm{CO}\) taken in a \(2.5 \mathrm{~L}\) flask is maintained at \(750 \mathrm{~K}\) along with a catalyst so that the following reaction can take place : $$ \mathrm{CO}(\mathrm{g})+2 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{CH}_{3} \mathrm{OH}(\mathrm{g}) $$ Hydrogen is introduced until the total pressure of the system is \(8.5\) atmosphere at equilibrium and \(0.08\) mole of methanol is formed. Calculate (i) \(K_{p}\) and \(K_{c}\) and (ii) the final pressure if the same amount of \(\mathrm{CO}\) and \(\mathrm{H}_{2}\) as before are used, but with no catalyst so that the reaction does not take place.

The conjugate base of \(\mathrm{HSO}_{4}^{-}\)in aqueous solution is ___ .

The solubility product \(\left(K_{s p}\right)\) of \(\mathrm{Ca}(\mathrm{OH})_{2}\) at \(25^{\circ} \mathrm{C}\) is \(4.42 \times 10^{-5}\). A 500 \(\mathrm{mL}\). of saturated solution of \(\mathrm{Ca}(\mathrm{OH})_{2}\) is mixed with equal volume of \(0.4 \mathrm{M} \mathrm{NaOH}\). How much \(\mathrm{Ca}(\mathrm{OH})_{2}\) in milligrams is precipitated?

The initial rate of hydrolysis of methyl acetate (1M) by a weak acid \((\mathrm{H} A, 1 \mathrm{M})\) is \(1 / 100^{\text {th }}\) of that of a strong acid \((\mathrm{H} X, 1 \mathrm{M})\), at \(25^{\circ} \mathrm{C}\). The \(K_{a}\) of \(\mathrm{H} A\) is (a) \(1 \times 10^{-4}\) (b) \(1 \times 10^{-5}\) (c) \(1 \times 10^{-6}\) (d) \(1 \times 10^{-3}\)

For the reaction : \(\mathrm{CO}(\mathrm{g})+2 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{CH}_{3} \mathrm{OH}(\mathrm{g})\) hydrogen gas is introduced into a five litre flask at \(327^{\circ} \mathrm{C}\), containing \(0.2\) mole of \(\mathrm{CO}(\mathrm{g})\) and a catalyst, until the pressure is \(4.92 \mathrm{~atm}\). At this point \(0.1\) mole of \(\mathrm{CH}_{3} \mathrm{OH}(\mathrm{g})\) is formed. Calculate the equilibrium constant, \(K_{p}\) and \(K_{c}\).

Aqueous solutions of \(\mathrm{HNO}_{3}, \mathrm{KOH}, \mathrm{CH}_{3} \mathrm{COOH}\) and \(\mathrm{CH}_{3} \mathrm{COONa}\) of identical concentrations are provided. The pair(s) of solutions which form a buffer upon mixing is(are) (a) \(\mathrm{HNO}_{3}\) and \(\mathrm{CH}_{3} \mathrm{COOH}\) (b) \(\mathrm{KOH}\) and \(\mathrm{CH}_{3} \mathrm{COONa}\) (c) \(\mathrm{HNO}_{3}\) and \(\mathrm{CH}_{3} \mathrm{COONa}\) (d) \(\mathrm{CH}_{3} \mathrm{COOH}\) and \(\mathrm{CH}_{3} \mathrm{COONa}\)

Freshly precipitated aluminium and magnesium hydroxides are stirred vigorously in a buffer solution containing \(0.25\) mole/L of ammonium chloride and \(0.05\) mole/ \(\mathrm{L}\) of ammonium hydroxide. Calculate the concentration of aluminium and magnesium ions in solution: \(K_{b}\left[\mathrm{NH}_{4} \mathrm{OH}\right]=1.80 \times 10^{-5}\) \(K_{s p}\left[\mathrm{Mg}(\mathrm{OH})_{2}\right]=6 \times 10^{-10}\) \(K_{s n}\left[\mathrm{Al}(\mathrm{OH})_{3}\right]=6 \times 10^{-32}\)

A buffer solution can be prepared from a mixture of (a) sodium acetate and acetic acid in water (b) sodium acetate and hydrochloric acid in water (c) ammonia and ammonium chloride in water (d) ammonia and sodium hydroxide in water

The equilibrium constant \(K_{p}\) of the reaction: $$ 2 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{SO}_{3}(\mathrm{~g}) $$ is 900 atm. at \(800 \mathrm{~K}\). A mixture containing \(\mathrm{SO}_{3}\) and \(\mathrm{O}_{2}\) having initial partial pressure of 1 and 2 atm. respectively is heated at constant volume to equilibrate. Calculate the partial pressure of each gas at \(800 \mathrm{~K}\).

Which of the following statements(s) is (are) correct? (a) The pH of \(1.0 \times 10^{-8} \mathrm{M}\) solution of \(\mathrm{HCl}\) is 8 (b) The conjugate base of \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)is \(\mathrm{HPO}_{4}^{2-}\) (c) Autoprotolysis constant of water increases with temperature (d) When a solution of a weak monoprotic acid is titrated against a strong base, at half-neutralisation pointpH \(=(1 / 2) \mathrm{p} K_{a}\).

At a certain temperature equilibrium constant \((K)\) is 16 for the reaction. $$ \begin{gathered} {[1987-5 \text { Marks }]} \\ \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{NO}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{SO}_{3}(\mathrm{~g})+\mathrm{NO}(\mathrm{g}) \end{gathered} $$ If we take one mole each of all the four gases in a one litre container, what would be the equilibrium concentrations of \(\mathrm{NO}(\mathrm{g})\) and \(\mathrm{NO}_{2}(\mathrm{~g})\) ?

The INCORRECT statement among the following, for this reaction, is (a) Decrease in the total pressure will result in formation of more moles of gaseous \(X\) (b) At the start of the reaction, dissociation of gaseous \(X_{2}\) takes place spontaneously (c) \(\beta_{\text {equilboium }}=0.7\) (d) \(K_{C}<1\)

One mole of \(\mathrm{Cl}_{2}\) and 3 moles of \(\mathrm{PCl}_{5}\) are placed in a 100 litre vessel heated to \(227^{\circ} \mathrm{C}\). The equilibrium pressure is \(2.05\) atmosphere. Assuming ideal behaviour, calculate the degree of dissociation for \(\mathrm{PCl}_{5}\) and \(K_{p}\) for the reaction: \(\mathrm{PCl}_{5}(\mathrm{~g}) \rightleftharpoons \mathrm{PCl}_{3}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g})\)

A solution contains a mixture of \(\mathrm{Ag}(0.10 \mathrm{M})\) and \(\mathrm{Hg}_{2}^{++}(0.10 \mathrm{M})\) which are to be separated by selective precipitation. Calculate the maximum concentration of iodide ion at which one of them gets precipitated almost completely. What percentage of that metal ion is precipitated? \(\left[K_{s p}: \mathrm{AgI}=8.5 \times 10^{-17} ; \mathrm{Hg}_{2} \mathrm{I}_{2}=2.5 \times 10^{-26}\right]\)

One mole of nitrogen is mixed with three moles of hydrogen in a 4 litre container. If \(0.25\) per cent of nitrogen is converted to ammonia by the following reaction $$ \mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_{3}(\mathrm{~g}) $$ calculate the equilibrium constant \(\left(K_{c}\right)\) in concentration units. What will be the value of \(K_{c}\) for the following equilibrium? $$ \frac{1}{2} \mathrm{~N}_{2}(\mathrm{~g})+\frac{3}{2} \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{NH}_{3}(\mathrm{ag}) $$

For the following Assertion and Reason, the correct option is [Main Sep. 02, \(\mathbf{2 0 2 0}\) (I)] Assertion (A) : When Cu (II) and sulphide ions are mixed, they react together extremely quickly to give a solid. Reason (R) : The equilibrium constant of \(\mathrm{Cu}^{2+}(\mathrm{aq})+\mathrm{S}^{2-}(\mathrm{aq}) \rightleftharpoons \mathrm{CuS}\) (s) is high because the solubility product is low. (a) Both \(\mathrm{S}\) and \(\mathrm{E}\) are true, and \(\mathrm{E}\) is the correct explanation of \(\mathrm{S}\). (b) Both \(\mathrm{S}\) and \(\mathrm{E}\) are true, but \(\mathrm{E}\) is not the correct explanation of \(\mathrm{S}\). (c) \(\mathrm{S}\) is true but \(\mathrm{E}\) is false. (d) \(\mathrm{S}\) is false but \(\mathrm{E}\) is true.

Arrange the following oxides in the decreasing order of Bronsted basicity: \(\mathrm{BaO}, \mathrm{SO}_{3}, \mathrm{CO}_{2}, \mathrm{Cl}_{2} \mathrm{O}_{7}, \mathrm{~B}_{2} \mathrm{O}_{3}\)

. \(500 \mathrm{~mL}\) of \(0.2 \mathrm{M}\) aqueous solution of acetic acid is mixed with 500 \(\mathrm{mL}\) of \(0.2 \mathrm{M} \mathrm{HCl}\) at \(25^{\circ} \mathrm{C} .\) (i) Calculate the degree of dissociation of acetic acid in the resulting solution and \(\mathrm{pH}\) of the solution. (ii) If \(6 \mathrm{~g}\) of \(\mathrm{NaOH}\) is added to the above solution, determine the final \(\mathrm{pH}\). [Assume there is no change in volume on mixing; \(K_{a}\) of acetic acid is \(\left.1.75 \times 10^{-5} \mathrm{~mol} \mathrm{~L}^{-1}\right]\).

A \(40.0 \mathrm{~mL}\) solution of weak base, \(\mathrm{BOH}\) is titrated with \(0.1 \mathrm{~N} \mathrm{HCl}\) solution. The \(\mathrm{pH}\) of the solution is found to be \(10.04\) and \(9.14\) after adding \(5.0 \mathrm{~mL}\) and \(20.0 \mathrm{~mL}\) of the acid respectively. Find out the dissociation constant of the base.

What is the \(\mathrm{pH}\) of \(1.0 \mathrm{M}\) solution of acetic acid? To what volume must one liter of this solution be diluted so that the \(\mathrm{pH}\) of the resulting solution will be twice the original value? Given : \(K_{a}=1.8 \times 10^{-5}\).

What is the \(\mathrm{pH}\) of the solution when \(0.20\) mole of hydrochloric acid is added to one litre of a solution containing. (i) \(1 \mathrm{M}\) each of acetic acid and acetate ion? (ii) \(0.1 \mathrm{M}\) each of acetic acid and acetate ion? Assume the total volume is one litre. \(K_{a}\) for acetic acid \(=1.8 \times 10^{-5}\)

increasing acid strength : \(\mathrm{HClO}_{3}, \mathrm{HClO}_{4}, \mathrm{HClO}_{2}, \mathrm{HClO}\)

increasing bond length : \(\mathrm{F}_{2}, \mathrm{~N}_{2}, \mathrm{Cl}_{2}, \mathrm{O}_{2}\)

The dissociation constant of a weak acid \(\mathrm{H} A\) is \(4.9 \times 10^{8}\). After making the necessary approximations, calculate (i) percentage ionization, (ii) \(\mathrm{pH}\) and (iii) \(\mathrm{OH}^{-}\)concentration in a decimolar solution of the acid. Water has a pH of 7 .

Twenty \(\mathrm{mL}\) of \(0.2 \mathrm{M}\) sodium hydroxide is added to \(50 \mathrm{~mL}\) of \(0.2 \mathrm{M}\) acetic acid to give \(70 \mathrm{~mL}\) of the solution. What is the \(\mathrm{pH}\) of this solution? Calculate the additional volume of \(0.2 \mathrm{M} \mathrm{NaOH}\) required to make the \(\mathrm{pH}\) of the solution 4.74. The ionization constant of acetic acid is \(1.8 \times 10^{-5}\).

A solution contains \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) and \(\mathrm{NaHCO}_{3} .10 \mathrm{~mL}\) of solution requires \(2.5 \mathrm{~mL}\) of \(0.1 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}\) for neutralisation using phenolphthalein as an indicator. Methyl orange is then added when a further \(2.5 \mathrm{~mL}\) of \(0.2 \mathrm{M}\) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) was required. Calculate the amount of \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) and \(\mathrm{NaHCO}_{3}\) in one litre of the solution