Rank these acids according to their expected pKa values. ClCH2COOHClCH2CH2COOHCH3CH2COOHCl2C HCOOHIn order of highest pka to lowest pka

CH₃CH₂CH₂COOH > CH₃CH₂COOH > ClCH₂CH₂COOH  > ClCH₂COOH

Explanation:

Electron-withdrawing groups (EWGs) increase acidity by inductive removal of electrons from the carboxyl group.

Electron-donating groups (EDGs) decrease acidity by inductive donation of electrons to the carboxyl group.

CH₃CH₂-CH₂COOH —  EDG —                         weakest —  pKₐ = 4.82

      CH₃-CH₂COOH — reference —                                     pKₐ = 4.75

  ClCH₂-CH₂COOH — EWG on β-carbon— stronger —     pKₐ = 4.00

           ClCH₂COOH — EWG on α-carbon — strongest —  pKₐ = 2.87

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.