Question

Assuming equal concentrations, rank these solutions highest to lowest by pH.

HF, HCl, NH3, NaOH, Sr(OH)2

Answer 1

NaOH > Sr(OH)2 > NH3 > HF > HCl

since naoh is one of the strongest base

AND HCl is more acidic in HF due to small size of F , due to which bond dissociation energy of HF is far more high than Hcl

Answer 2

Hhihest pH to Lowest pH

pH of

NaOH> Sr(OH)2 > NH3> HF> HCl

Reason:

When NaOH dissolves in water, it completely dissociates into its component ions, Na+ and OH-. The concentration of OH- makes the water basic, so it will be a strong base and have a high pH

Although Sr(OH)2 has two dissociable hydroxides, it is very slightly soluble in water, it will not put many OH- ions into the water; therefore it will be a weak base.

NH3 (Ammonia) is also a weak base; when placed in water, it forms the ammonium ion, NH4+, therefore removing acidity from the water. This reaction is weaker than ionic OH- dissociation since it's not adding new OH- ions to the water.

With increase in atomic size from F to I ,bond length of H----X bond increases and so bond dissociation energy decreases. Hence,ionisation of H---X increases,therefore acidic strength increases in the order
HF < HCl < HBr < HI