To rank the solutions in order of increasing pH, we need to consider the nature of the ions and compounds present in each solution and how they affect the pH. The pH of a solution is determined by the concentration of hydrogen ions (H⁺). Here's the ranking in increasing pH:
NH₃ (Ammonia Solution):
NH₃ is a weak base.
It accepts a proton (H⁺) from water to form NH₄⁺ and OH⁻ ions.
Higher OH⁻ concentration leads to a higher pH.
So, NH₃ will have the highest pH among these solutions.
NH₄Br (Ammonium Bromide Solution):
NH₄Br is the salt of NH₄⁺ and Br⁻ ions.
NH₄⁺ can act as a weak acid by donating an H⁺ ion.
However, it's less acidic than HBr.
NH₄Br will have a slightly higher pH than HBr but lower than NH₃.
HBr (Hydrobromic Acid Solution):
HBr is a strong acid that dissociates completely in water, producing a high concentration of H⁺ ions.
It has a very low pH, making it the most acidic solution among these.
KBr (Potassium Bromide Solution):
KBr is the salt of K⁺ and Br⁻ ions.
Neither K⁺ nor Br⁻ ions significantly affect the pH.
It will have a neutral pH (around 7) because it doesn't contribute to the concentration of H⁺ or OH⁻ ions.
So, the ranking of the solutions in increasing pH is as follows:
HBr (lowest pH, most acidic)
NH₄Br
KBr (neutral pH)
NH₃ (highest pH, most basic)