Equilibrium

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: At a given time the reaction quotient Q for the reaction will be given by the expression:

Q= $\frac{\left[\mathbf{H}2\right]\left[\mathbf{I}2\right]}{\left[\mathbf{H}\mathbf{I}\right]\mathrm{}}$  = $\frac{[1*10??*1*10??]}{{\left(2*\mathrm{}10^{-5}\right)}^2}$  = $\frac{1}{2}\mathrm{}$ = 0.25

 = 2.5*10⁻¹

As the value of the reaction quotient is greater than the value of K_c i.e. 1*10⁻⁴ the reaction will proceed in the reverse direction.

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: Correct order of pH is -

NH₄Cl  C₆H₅COONH₄  KNO₃  CH₃COONa

Salts of strong acid and strong base do not hydrolyse and form neutral solution thus, pH will be nearly 7 of KNO₃?  

In sodium acetate, acetic acid remains unionised this results in increase in OH- concentration and pH will be more than 7. 

NH₄Cl formed from weak base,  NH₄OH and strong acid,  HCl, in water dissociates completely, aq. ammonium ions undergo hydrolysis with water to form NH₄OHand H₊ ions resulting in less pH value.

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Ans: Conjugate acid of a weak base is always stronger and conjugate base of weak acid is always strong.

The weak acids are:

⇒H₂O, ROH, CH₃COOH, HCl

⇒HCl > CH₃COOH > ROH > H₂O

⇒ Conjugate base order ⇒ OH⁻>RO⁻>CH₃COO⁻>Cl⁻

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: Higher the value of Kb stronger will be the base. 

K_b-  5.4 * 10^-4 >1.77 * 10^-5 > 1.77 * 10^-9> 1.3 * 10^-14

Decreasing order of basic strength. 

Dimethylamine > Ammonia > Pyridine > Urea

Hence among the given bases, the strongest base is Dimethylamine. 

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Ans: BF₃ does not have a proton but still it acts as a Lewis acid as it is an electron pair acceptor and reacts with NH₃by accepting its lone pair of electrons. The reaction can be represented by Coordinate bond is formed between BF₃ and NH₃. It can be represented as-

  [ BF₃ ← :NH₃]

Nitrogen acts as lone pair donator in this combination

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Ans: Conductance of a solution depends upon the number of ions present in the solution since sodium chloride is an ionic compound when mixed in water it ionizes completely forming an aqueous electrolytic solution. Hence, the solution conducts electricity while sugar being a non-electrolyte does not ionize in water and when concentration of NaCl is increased, more Na⁺ and Cl^-  ions will be produced. Hence, conductance increases.

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Ans: Conjugate acid and conjugate base can be shown as-

HCl(aq) + H₂O (l) ? H₃O⁺(aq) + Cl^-(aq) 

 acid        base        conjugate    conjugate

                             acid          base

This is a Long Answer Type Questions as classified in NCERT Exemplar

Ans: The equation can be written as-

A^p+_x  +  B^q- _y ? xA^p+ (aq) +  yB^q-

S moles of A and B dissolves to give x S moles of A^p+ and y S moles of Bq-.

K_sp = [A^p+]^x  [B^q-]^y = [x5]^x [y5]^y

= x^x y ^y 5 ^x+y

This is a Long Answer Type Questions as classified in NCERT Exemplar

Ans: According to Le Chatelier's principle, when we raise the temperature, it shifts the equilibrium to left and decreases the equilibrium concentration of ammonia since it is an exothermic reaction. In other words, low temperature and high pressure is favourable for high yield of ammonia. There will be no change in equilibria on addition of argon (Ar).