You are given an aqueous salt solution and have determined that its pH is 5.19 at 25°C. Predict which of the following three salt solutions it is most likely to be.

solution (1): a solution of ammonium nitrate (NH4NO3)

solution (2): a solution of potassium bromate (KBrO3)

solution (3): a solution of rubidium cyanide (RbCN)

Please don't change screen names. Use any you wish but keep the same one. It makes it much easier to help you.

The pH is determined by the hydrolysis of the salt. The proper way to do this is to solve for Kb or Ka and compare but I have an easier way to do. Your prof may or may not approve but it gets the answer every time, takes less time, BUT may not be up to snuff with theory.
NH4NO3 + HOH ==> NH4OH + HNO3
KBrO3 + HOH ==> KOH + HBrO3
RbCN + HOH ==> HCN + RbOH

Now you look at the equations. I'll choose the last one.
HCN is a weak acid and RbOH is a strong base; therefore, the solution will be basic. A pH of 5.19 is acidic so this one can't be right. Now you go through the other two tghe same way. Pick the one that is acidic. Post your work/thinking if you get stuck.By the way, you may know NH4OH as NH3 + H2O.

To predict which of the three salt solutions is most likely to have a pH of 5.19, we need to consider the properties of the anions and cations present in each solution.

1. Ammonium nitrate (NH4NO3):
Ammonium ions (NH4+) can be acidic because they can donate a proton, while nitrate ions (NO3-) are neutral. The presence of NH4+ ions suggests that the solution could be acidic, lowering the pH. Therefore, solution (1) is a possible candidate for a pH of 5.19.

2. Potassium bromate (KBrO3):
Both potassium ions (K+) and bromate ions (BrO3-) do not actively participate in acid-base reactions, and they are considered neutral. Therefore, the presence of KBrO3 is less likely to influence the pH significantly. Solution (2) is less likely to have a pH of 5.19.

3. Rubidium cyanide (RbCN):
Rubidium ions (Rb+) are similar to potassium ions and do not actively participate in acid-base reactions. Cyanide ions (CN-) are basic because they can accept a proton. The presence of CN- ions suggests that the solution could be basic, increasing the pH. Therefore, solution (3) is less likely to have a pH of 5.19.

Based on this analysis, solution (1) containing ammonium nitrate (NH4NO3) is the most likely candidate to have a pH of 5.19.