CH-1080

Strong and weak acids

Chemistry · Secondary 4 · Hard · Strong and weak acids

The dissociation constants of two carboxylic acids are:

- Ethanoic acid, CH

_3

COOH:

K_a = 1.8 \times 10^{-5}

- Chloroethanoic acid, CH

_2

ClCOOH:

K_a = 1.4 \times 10^{-3}

Which statement explains why chloroethanoic acid is stronger?

The electronegative Cl atom withdraws electrons, stabilising the carboxylate ion and increasing $K_a$
The Cl atom donates electrons, making the carboxylate ion more negative and less stable
The Cl atom makes the molecule non-polar so it cannot dissociate
The Cl atom lowers the electronegativity of the oxygen atoms

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