Mention at least two simple chemical tests by which you can distinguish between benzaldehyde and benzoic acid.

Verified step by step guidance

1. Identify the functional groups present in benzaldehyde and benzoic acid. Benzaldehyde contains an aldehyde group (-CHO), while benzoic acid contains a carboxylic acid group (-COOH).
2. Consider the Tollens' test, which is used to detect aldehydes. Benzaldehyde, being an aldehyde, will react with Tollens' reagent to form a silver mirror on the test tube, while benzoic acid will not react.
3. Consider the sodium bicarbonate test, which is used to detect carboxylic acids. Benzoic acid will react with sodium bicarbonate (NaHCO₃) to produce carbon dioxide gas (bubbling), while benzaldehyde will not react.
4. Review the results of the Tollens' test and sodium bicarbonate test to distinguish between benzaldehyde and benzoic acid based on their reactivity.
5. Summarize the findings: Benzaldehyde will give a positive Tollens' test (silver mirror) and a negative sodium bicarbonate test (no bubbling), whereas benzoic acid will give a negative Tollens' test (no silver mirror) and a positive sodium bicarbonate test (bubbling).

Key Concepts

Functional Groups

Benzaldehyde and benzoic acid are both aromatic compounds but differ in their functional groups. Benzaldehyde contains an aldehyde group (-CHO), while benzoic acid has a carboxylic acid group (-COOH). Understanding these functional groups is essential for distinguishing between the two compounds, as they dictate the chemical reactivity and properties of the molecules.

Chemical Tests

Chemical tests are specific reactions used to identify the presence of certain functional groups in organic compounds. For instance, the Tollens' test can be used to detect aldehydes like benzaldehyde, which will reduce silver ions to metallic silver, while benzoic acid does not react. Conversely, benzoic acid can be tested with sodium bicarbonate, which will produce carbon dioxide gas due to the acid's reactivity, whereas benzaldehyde will not.

Solubility Differences

The solubility of benzaldehyde and benzoic acid in water is another distinguishing factor. Benzoic acid is more soluble in water due to its ability to form hydrogen bonds through its carboxylic acid group, while benzaldehyde is less soluble. This difference can be exploited in separation techniques or tests to differentiate between the two compounds based on their solubility characteristics.