Assuming equal concentrations rank these solutions by pH Hig

Assuming equal concentrations, rank these solutions by pH. Highest pH Lowest pH Sr(OH)2(aq) HCN(aq) NH3(aq) KOH(aq) HCIO4(aq)

Ans. # HClO₄ is a strong acid. So, it’s solution has highest [H⁺], and in turn, lowest (most acidic) pH.

# Sr(OH)₂ is a strong base that gives 2 mol OH^- per mol base. Therefore, it’s solution has highest [OH^-] and in turn highest (most alkaline) pH.

# KOH is also a strong base that gives 1 mol OH^- per mol base. So, this solution has a pH lower than that of Sr(OH)₂.

# HCN is a weak acid with pKa of 9.21. NH3 is a weak base with pKa of 38.0.

Lower is the pKa value, stronger is the acid.

So, solution of HCN is acidic than that of NH₃.

# So, order of pH (from highest to lowest) is-

(highest pH, most alkaline) Sr(OH)₂ > KOH > NH₃ > HCN > HClO₃ (lowest pH, most acidic)