Equilibrium
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A buffer solution is prepared in which the concentration of NH3 is 0.30 M and the concentration of NH4 is 0.20 M. If the equilibrium constant, Kb for NH3 equals 1.8 x 10-5, what is the pH of this solution?
log ( 2.7 = 0.43)
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9.43
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11.72
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8.73
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9.08
A.
9.43
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A Weak acid, HA has a Ka of 1.00 x 10-5. If 0.100 mole of this percentage of acid dissociated at equilibrium is closest to:
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99.0%
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1.00%
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99.9 %
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0.100%
B.
1.00%
An aqueous solution of which of the following compounds is the best conductor of electric current?
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Acetic acid C2H4O2
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Hydrochloric acid, HCl
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Ammonia, NH3
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Fructose, C6H12O6
B.
Hydrochloric acid, HCl
HCl is strong acid and dissociates completely. Hence, it conducts electricity best in its aqueous solution.
Base strength of 
is in the order of
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(2) > (1) > (3)
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(3) > (2) > (1)
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(1) > (3)> (2)
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(1) > (2) > (3)
D.
(1) > (2) > (3)
Stronger the acid, weaker is its conjugate base.
The strength of their conjugate acids are in the order: 
Therefore, the correct order of strength of their conjugate base is: 
Buffer solutions have constant acidity and alkalinity because
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these give unionised acid or base on reaction with added acid or alkali
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acids and alkalies in these solutions are shielded from attack by other ions.
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they have a large excess of H+ or OH- ions
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they have fixed value of pH
A.
these give unionised acid or base on reaction with added acid or alkali
If a small amount of an acid or alkali is added to a buffer solution, it converts them into unionised acid or base. Thus, remains unaffected or in other words its acidity/alkalinity remains constant. e.g.,
H3O+ + A- ⇌ H2O +HA
-OH +HA → H2O +A-
If acid is added, it reacts with A- to form undissociated HA. Similarly, if base/alkali is added, O H- combines with HA to give H2O and A- and thus, maintains the acidity/alkalinity of buffer solution.
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Mock Test Series
Mock Test Series