100ml of 1N NH4OH (Kb=5x10-5) is neutralized to equivalence point by 1...
Meq. of NH
4OH = Meq. of HCI
= Meq. of NH
4CI formed
100 x 1=1xV
= Meq. of NH
4CI
Also, V = 100 mL
Due to hydrolysis of NH
4CI;
∴ pH = 5
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100ml of 1N NH4OH (Kb=5x10-5) is neutralized to equivalence point by 1...
The given problem involves the neutralization of NH4OH (ammonium hydroxide) with HCl (hydrochloric acid). To find the pH at the equivalence point, we need to understand the reaction and the concept of equivalence point.
1. Reaction equation:
NH4OH + HCl → NH4Cl + H2O
2. Equivalence point:
The equivalence point is the point in a titration where the moles of the acid and base are equal. In this case, 100 mL of 1N NH4OH is neutralized by 1N HCl. Since both solutions have the same concentration, the moles of NH4OH and HCl will be equal at the equivalence point.
3. Calculation of moles:
Moles = concentration (N) x volume (L)
Moles of NH4OH = 1N x 0.1 L = 0.1 moles
Moles of HCl = 1N x 0.1 L = 0.1 moles
Since the moles of NH4OH and HCl are equal, they will react completely according to the balanced equation.
4. Formation of NH4Cl:
During the neutralization reaction, NH4OH reacts with HCl to form NH4Cl and water. Since NH4Cl is a salt, it will dissociate completely in water to form NH4+ and Cl- ions.
NH4Cl → NH4+ + Cl-
5. pH at equivalence point:
At the equivalence point, the solution will contain equal concentrations of NH4+ and Cl- ions. NH4+ is the conjugate acid of NH4OH, and Cl- is the conjugate base of HCl.
NH4+ is a weak acid, and Cl- is a weak base. Therefore, the solution will be slightly acidic. The pH of the solution at the equivalence point will depend on the relative strengths of the conjugate acid and base.
In this case, NH4+ is a weaker acid compared to HCl, so the solution will be more acidic. The pH will be less than 7 but not as low as 1 or 2.5.
Therefore, the correct answer is option 'D' - pH 5.