The pKa of 4-nitrophenol is 7.15. Would you expect it to dissolve into a solution of sodium bicarbonate? The pKa of 2,5-dinitrophenol is 5.15. Would it be expected to dissolve in sodium bicarbonate solution? Explain your reasoning. Hint: Carbonic acid pKa is 6.4.

Explanation:

p-Nitrophenol pKa = 7.15 would be expected to dissolve in bicarbonate because it is a weaker acid than carbonic acid with Pka of 6.4

The 2,5-dinitrophenol with pka of 5.15 would not be expected to dissolve in bicarbonate because it is a stronger acid than carbonic acid with Pka of 6.4

The Lower the pKa value the stronger is the acid. Only a stronger acid than carbonic acid, will dissolve in bicarbonate.

The Lower the pKa value, the stronger is the acid.For bicarbonate to dissolve nitrophenol, then bicarbonate has to attract a proton from nitrophenol in order to for nitrophenolate which is a soluble comoound ,Since The pKa value of bicarbonate is 6.4 which is lower compare to the pKa value of nitrophenol, As a result of the lower pKa of the bicarbonate, It makes it to be a stronger acid and stronger acids cannot abstract protons from a weaker acid.

Therefore, nitrophenol with Pka of 7.15 cannot dissolve in bicarbonate solution with Pka of 6.4 but 2,5-dinitrophenol with Pka of 5.15 will dissolve

it forms an anion that has a larger radius. anions have a negative charge and are larger than the original atom.