Using pK_a values: HC#CH 25, C6H5OH 10.0, CH3COOH 4.76, C2H5OH 15.9, NH3 38, H2O 15.7, H2CO3 6.4, H2 35, which of the following acid-base reactions has the largest equilibrium constant?

CH3COOH + NaHCO3 -> CH3COONa + H2CO3

JEE Advanced levelSingle correct optionDifficulty 3 of 3g2129

Using $p K_{a}$ values: $HC \equiv CH$ 25, $C X_{6} H X_{5} OH$ 10.0, $CH X_{3} COOH$ 4.76, $C X_{2} H X_{5} OH$ 15.9, $NH X_{3}$ 38, $H X_{2} O$ 15.7, $H X_{2} CO X_{3}$ 6.4, $H X_{2}$ 35, which of the following acid-base reactions has the largest equilibrium constant?

lo g K

p K_{a}

(conjugate acid of base)

-

p K_{a}

(acid): ethanol/NaH

= 35 - 15.9 = 19.1

; acetylene/

NaNH X_{2}

= 38 - 25 = 13

; phenol/NaOH

= 15.7 - 10.0 = 5.7

; acetic acid/

NaHCO X_{3}

= 6.4 - 4.76 = 1.64

. The largest is the ethanol/NaH reaction.