Question

Adding bicarbonate to a solution will cause the pH to:

(a) go up
(b) go down
(c) will not affect pH
(d) reverse the polarity

Answer 1

Adding bicarbonate to a solution raises the pH level because bicarbonate is a weak base that can reduce the concentration of hydrogen ions. When mixed with an acid like vinegar, bicarbonate can create a temporary increase in pH followed by stabilization due to buffer formation.

Step-by-step explanation:

Adding bicarbonate to a solution will cause the pH to increase. This happens because bicarbonate (HCO3−) is a weak base and can accept hydrogen ions (H+), thereby reducing the concentration of hydrogen ions in the solution and raising the pH. When acids and bases are mixed, they can neutralize each other.

For example, when vinegar (acetic acid, CH3COOH) is mixed with baking soda (sodium bicarbonate, NaHCO3), a chemical reaction occurs in which carbon dioxide gas, water, and sodium acetate are formed:

CH3COOH(aq) + NaHCO3(s) → CO2(g) + H2O(l) + NaCH3COO(aq)

After mixing these substances, the pH of the solution will generally increase briefly as the bicarbonate neutralizes some of the acetic acid, and then it may stabilize due to the formation of a buffer solution with the sodium acetate that is produced.