Chemistry help please fast?

Question

A carboxylic acid is in a organic acid based on the carboxylate function group,-COOH-. The pKa of acetic acid CH3COOH, is 4.74. The pKa of chloroacetic acid, CH2ClCOOH, is 2.86. The pKa Of try chloro acidic acid, CCL3COOH, is 0.66. Acetic acid diluted in water is known as vinegar, which is safe for mini food, cleaning, and alternative health applications. The other two acids are quite hazardous to help in addition to being stronger acid’s, and the reactivity make some useful as reagents in organic synthesis. Consider what trend exists in the PKA values for these three carboxylic acid based on the molecular formulas, then complete the following statements regarding the trend that relates to this phenomenon.

Consider what trend exists in the PKA values for these three carboxylic acid’s based on the molecular formulas, then complete the following statements regarding the trend that relates to this phenomenon.

The PK values of carboxyl assets 10 to decrease as the… ??Increases.

i don’t know what increases

Answer 1

Hi Kira!

The acidity of an aqueous compound is determined by its pKa. In general the lower the pKa the greater the acidity.

The problem presents you with 3 acids: acetic acid (CH₃COOH), chloroacetic acid (CH₂ClCOOH) and trichloroacetic acid (CCl₃COOH). Notice that the 2 latter acids are simply derivatives of acetic acid, each having an additional chlorine. You should also notice the trend of decreasing pKa (increasing acidity) as you add more chlorines. Remember the definition of Bronsted acid: a proton donor. When deprotonated, the conjugate base of a strong acid will be better stabilized by nearby electronegative atoms (such as chlorine) which pull electron density towards themselves. This a phenomenon known as the inductive effect. In general, if you have the same functional group throughout, as seen here (i.e. all forms of acetic acid), then the more electronegative atoms you add the stronger the acid will be since the conjugate base gains even more stability.

I hope this made sense. Best of luck!