Question: Arrange each group of compounds in order of increasing acidity.

1. phenol, ethanol, acetic acid
2. p-toluenesulfonic acid, acetic acid, chloroacetic acid
3. benzoic acid, o-nitrobenzoic acid, m-nitrobenzoic acid
4. butyric acid, $\alpha$-bromobutyric acid, $\beta$-bromobutyric acid
5. 
   

a. Phenol and acetic acid react with NaOH, whereas ethanol (alcohol) does not react with NaOH. Carboxylic acids are more acidic than alcohol and phenol because they react with weak bases like or . Thus, the order of increasing acidity is, ethanol < phenol < acetic acid.

b. The pKa values of p-toluenesulfonic acid, acetic acid, and chloroacetic acid are -7, 4.8, and 2.86. Lower the value, the higher the acidity of a compound. Thus, the order of increasing acidity is, acetic acid < chloroacetic acid < p-toluenesulfonic acid.

c. The acidity of o-nitrobenzoic acid and m-nitrobenzoic acid is higher than benzoic acid because of the presence of the electron-withdrawing group (-NO₂). Now, o-nitrobenzoic acid has higher acidity than m-nitrobenzoic acid because of intramolecular hydrogen bonding, which makes the proton removal difficult. Thus, the order of increasing acidity is, benzoic acid < m-nitrobenzoic acid < o-nitrobenzoic acid.

d. The acidity of $\alpha$-bromobutyric acid and $\beta$-bromobutyric acid is higher than butyric acid because of one electron-withdrawing group (-Br). Now,$\beta$ -bromobutyric acid has higher acidity than -bromobutyric acid because the Br group is present closer. We know that acidity increases with the close proximity of the electron-withdrawing group. Thus, the order of increasing acidity is, butyric acid < $\delta$-bromobutyric acid < $\alpha$-bromobutyric acid.

e. The acidity of the given compounds is based on the position of halogen atoms from a carboxylic acid. In a compound having an F group, the halogen is present at the same carbon to which carboxylic acid is attached. So, it stabilizes the carboxylate conjugate base and thus increases the acidity. Then, compound with the Cl group, it is present at the carboxylic acid's adjacent carbon, which has slightly lower acidity. Thus, the order of increasing acidity is,