Which substance can be added to raise the pH?

Which substance can be added to raise the pH?

• A. Sodium bicarbonate
• B. Dissolved oxygen
• C. Hydrochloric acid
• D. Sodium thiosulfate

Answer: (A)

Raising pH means decreasing the hydrogen ion concentration in solution, which happens when you add a base. Sodium bicarbonate is a mild base that reacts with acids to neutralize them, forming carbonic acid that quickly becomes CO2 and water. This neutralization removes free H+ from the solution, pushing the pH higher. Dissolved oxygen doesn’t change acidity, and hydrochloric acid adds H+, lowering pH. Sodium thiosulfate is not used to raise pH in typical contexts. So, sodium bicarbonate best increases pH.

Raising pH means decreasing the hydrogen ion concentration in solution, which happens when you add a base. Sodium bicarbonate is a mild base that reacts with acids to neutralize them, forming carbonic acid that quickly becomes CO2 and water. This neutralization removes free H+ from the solution, pushing the pH higher. Dissolved oxygen doesn’t change acidity, and hydrochloric acid adds H+, lowering pH. Sodium thiosulfate is not used to raise pH in typical contexts. So, sodium bicarbonate best increases pH.