Question

Which of the following acids has the smallest dissociation constant?

• A. $CH _{3} CHFCOOH$
• B. $FCH_{2}CH_{2}COOH$
• C. $BrCH_{2}CH_{2}COOH$
• D. $CH_{3}CHBrCOOH$

Answer 1

Answer: (C)

$BrCH_{2}CH_{2}COOH$

Answer 2

Group or atom attached with $- COOH$ group shows negative inductive effect, makes the acid stronger or acid has the larger dissociation constant. -Br shows poor negative inductive effect and also far away from $- COOH$, which makes $Br CH _{2} CH _{2} COOH$ weakest acid and hence, it has smallest dissociation constant.