what two tests can I use to determine if a comound is an alcohol or a short or long chained carboxylic acid. I have two substances a colourless liquid and a white solid.
I would try an aqueous solution with litmus paper. Alcohols are neutral and carboxylic acids are acidic. Second test is to add NaHCO3. Carboxylic acids evolve CO2 gas.
Comparing the boiling points could also be an option.
Carboxylic acid has a larger boiling point than alcohol.
Short chained carboxylic acid tend to have a lower boiling point than long chained carboxylic acid (more number of carbons).
I am not sure if you are looking for physical or chemical tests. Also is the expected alcohol primary, secondary or tertiary?
From experience the appearance of simple carboxylic acids are glassy solids, whereas alcohols are waxy solids. The latter tend to 'set' rather than crystalise.
Solubility in an alkaline solution would also be useful. Dissolve a small amount of each in a solvent and extract with 0.1 M NaOH. Separate the phases. Add 0.1 M HCl until the aqueous phase is acid. If the aqueous phase goes cloudy, then the sample was the acid. The alcohol sample might result in a slight haze with the HCl, but the acid sample should go very cloudy.
To determine if a compound is an alcohol or a short or long-chained carboxylic acid, you can use two tests: the solubility test and the pH test.
1. Solubility Test:
- Take a small amount of the white solid and the colorless liquid separately.
- First, add a few drops of each substance into a test tube containing water.
- Shake the test tube gently and observe if the substance dissolves.
- If the substance dissolves completely, it is likely an alcohol since alcohols are generally soluble in water.
- If the substance does not dissolve or only partially dissolves, it could be a carboxylic acid since they are often insoluble or have limited solubility in water.
2. pH Test:
- Take small samples of each substance and place them separately on a pH testing strip or use a pH indicator solution.
- If the pH turns acidic (pH value less than 7), it suggests that the substance is likely a carboxylic acid. Carboxylic acids are acidic in nature.
- However, if the pH is neutral (around pH 7) or slightly basic (pH value greater than 7), then it indicates that the substance is likely an alcohol.
Please note that these tests provide initial indications and are not definitive. For a more accurate identification, further tests such as spectroscopy (e.g., infrared spectroscopy or nuclear magnetic resonance spectroscopy) may be required.