Consider the following chemical reaction of bromothymol blue indicator. it appears yellow in undissociated form and blue in its dissociated aqueous solution. hc2h3o2(aq) mc012-1.jpg h+(aq) + c2h3o2–(aq) yellow blue what will be the color of the solution if a large amount of h2co3 is added? the solution will remain yellow. the solution will turn blue. the solution will turn pink. the solution will turn green.

Answer is: The solution will remain yellow.

Balanced chemical reaction: HC₂H₃O₂(aq) ⇄ H⁺(aq) + C₂H₃O₂⁻(aq).

Carbonic acid dissociation in water: H₂CO₃ ⇄ H⁺(aq) + HCO₃⁻(aq).

According to Le Chatelier's Principle the position of equilibrium moves to counteract the change.

The position of equilibrium will move so that the concentration of hydrogen cations (H⁺) decreases and than concetration of acid (HC₂H₃O₂) increases.

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.