Use pKa values (in water): acetic acid 4.76, phenol 10.0, ethanol 15.9, pentane-2,4-dione 9.0, propanone 19.3. For which of the following reactions is the equilibrium constant much greater than 1 (more than $1 0^{3}$ )?

A $CH X_{3} COOH + C X_{6} H X_{5} O X^{-} CH X_{3} COO X^{-} + C X_{6} H X_{5} OH$
B $C X_{2} H X_{5} OH + C X_{6} H X_{5} O X^{-} C X_{2} H X_{5} O X^{-} + C X_{6} H X_{5} OH$
C $CH X_{3} COCH X_{2} COCH X_{3} + C X_{2} H X_{5} O X^{-} CH X_{3} COCHCOCH X_{3} X^{-} + C X_{2} H X_{5} OH$
D $CH X_{3} COCH X_{3} + C X_{2} H X_{5} O X^{-} CH X_{3} COCH X_{2} X^{-} + C X_{2} H X_{5} OH$

Answer: A, C

K equals

1 0^{p K_{a} (acid on right) - p K_{a} (acid on left)}

. Option 1:

1 0^{10.0 - 4.76} = 1.7 \times 1 0^{5}

. Option 2:

1 0^{10.0 - 15.9} = 1.3 \times 1 0^{- 6}

. Option 3:

1 0^{15.9 - 9.0} = 7.9 \times 1 0^{6}

. Option 4:

1 0^{15.9 - 19.3} = 4.0 \times 1 0^{- 4}

. So options 1 and 3.