in which of the following pairs of solutions ,where thre is no effect on the PH after dilution?
a)0.1M NH3 & 0.1M (NH4)taken twise SO4
C)0.1M HCL & 0.01M KOH
B)O.1MNaH2p04 & 0.1M Na2HPO4
D)0.1M KCL AND 0.1M HCL
Buffer solutions keep the pH on dilution; non-buffered solutions do not. Do you know how to spot a buffered solutiion? A buffer is made of either
a. a weak acid and its salt.
b. a weak base and its salt.
To determine which pair of solutions will not have an effect on the pH after dilution, we need to consider the nature of the substances in each pair.
A) 0.1M NH3 & 0.1M (NH4)2SO4
- NH3 is a weak base, while (NH4)2SO4 is a salt of a weak acid and its conjugate base. When NH4)2SO4 dissociates in water, it forms NH4+ and SO4- ions. The NH4+ ions can react with water to form NH3 and H3O+ ions, and this will affect the pH. Therefore, dilution of this pair will have an effect on the pH.
B) 0.1M HCl & 0.01M KOH
- HCl is a strong acid, and KOH is a strong base. When dissolved in water, they dissociate into H+ and Cl- ions, and KOH dissociates into K+ and OH- ions. The presence of strong acid and base ions will affect the pH, so dilution of this pair will have an effect on the pH.
C) 0.1M NaH2PO4 & 0.1M Na2HPO4
- NaH2PO4 is a weak acid, and Na2HPO4 is a salt of a weak acid and its conjugate base. When dissolved in water, NaH2PO4 partially dissociates into H+ and HPO4- ions, and Na2HPO4 dissociates into Na+ and HPO4- ions. The HPO4- ions can act as a weak base, partially reacting with water to form OH- ions. This will affect the pH, so dilution of this pair will have an effect on the pH.
D) 0.1M KCl & 0.1M HCl
- KCl is a salt formed from the strong acid HCl and the strong base KOH. When dissociated in water, it forms K+ and Cl- ions. Since both HCl and KCl are strong electrolytes, they will not react with water to affect the pH. Therefore, dilution of this pair will not have an effect on the pH.
So, the correct answer is option D) 0.1M KCl and 0.1M HCl.