This question is about two different types of organic acids: carboxylic acids and sulfonic acids.
Predict the bond angles aaa and bbb and name the molecular shapes around the central atom for:
- The carbonyl carbon in ethanoic acid, bond angle aaa.
- The sulfur atom in methanesulfonic acid, bond angle bbb.
Ethanoic acid, CH3COOH\text{CH}_3\text{COOH}CH3COOH, and methanesulfonic acid, CH3SO2OH\text{CH}_3\text{SO}_2\text{OH}CH3SO2OH, are both monobasic acids. Their pKa\text{p}K_apKa values are shown in the table below:
| Acid | Formula | pKa\text{p}K_apKa |
|---|---|---|
| Ethanoic acid | CH3COOH\text{CH}_3\text{COOH}CH3COOH | 4.76 |
| Methanesulfonic acid | CH3SO2OH\text{CH}_3\text{SO}_2\text{OH}CH3SO2OH | -1.90 |
A student claims that a 0.050 mol dm−30.050\text{ mol dm}^{-3}0.050 mol dm−3 solution of methanesulfonic acid will have a lower pH\text{pH}pH value than a 0.050 mol dm−30.050\text{ mol dm}^{-3}0.050 mol dm−3 solution of ethanoic acid.
Write an equation, showing conjugate acid–base pairs, for the equilibrium of CH3SO2OH\text{CH}_3\text{SO}_2\text{OH}CH3SO2OH with water, and explain with reasons whether the student's claim is correct. Label the conjugate acid–base pairs as A1, B1 and A2, B2.