Which of the following solutions would have the highest pH?

Which of the following solutions would have the highest pH?

• A. H2SO4
• B. NH4Cl
• C. KNO3
• D. NaOH

Answer: (D)

pH tells you how acidic or basic a solution is, which depends on the balance of hydronium and hydroxide ions in water. Bases raise pH by increasing the concentration of OH− ions. A strong base like sodium hydroxide dissociates completely in water to give a large amount of OH−. That makes the solution highly basic, producing the highest pH among these options. The strong acid sulfuric acid adds lots of H+ (or H3O+), so it makes the solution acidic with a low pH. The ammonium salt NH4Cl provides NH4+, which acts as a weak acid in water and lowers pH. Potassium nitrate from a strong acid and a strong base is essentially neutral because neither ion hydrolyzes significantly, giving a pH around 7. Thus, the solution with the highest pH is the one from the strong base.

pH tells you how acidic or basic a solution is, which depends on the balance of hydronium and hydroxide ions in water. Bases raise pH by increasing the concentration of OH− ions.

A strong base like sodium hydroxide dissociates completely in water to give a large amount of OH−. That makes the solution highly basic, producing the highest pH among these options.

The strong acid sulfuric acid adds lots of H+ (or H3O+), so it makes the solution acidic with a low pH. The ammonium salt NH4Cl provides NH4+, which acts as a weak acid in water and lowers pH. Potassium nitrate from a strong acid and a strong base is essentially neutral because neither ion hydrolyzes significantly, giving a pH around 7.

Thus, the solution with the highest pH is the one from the strong base.