How to differentiate phenol, acetic acid, aniline & nitrobenzene

In summary: Phenol, -0.89Acetic acid, 0.38Aniline, 10.0Nitrobenzene, 8.0Na2CO3, 11.0HCl, 1.0The pH of the bicarb solution will be 11.
  • #1
songoku
2,293
325

Homework Statement


The question actually contains a diagram but i don't understand how to draw it, so i'll try to describe it in words.
A solution contains phenol, acetic acid, aniline and nitrobenzene. Na2CO3 is added into the solution and two layers are formed: aqueous layer A and ethereal layer X. Then NaOH is added into ethereal layer X, two layers are formed: aqueous layer B and ethereal layer Y. At last, dilute HCl is added into ethereal layer Y and aqueous layer C and ethereal layer D is formed. The question is, identify the correct combinations of compound A, B, C and D.


Homework Equations





The Attempt at a Solution


I am really weak in organic chemistry. I tried to check the characteristics but i don't get it :cry: well, this is my guess: phenol, acetic acid and nitrobenzene is acidic while aniline is alkaline. so when Na2CO3 is added, it will react with those three and leaves aniline unreacted. then A is aniline. then i got confused :confused: i really don't have any idea. and I'm not sure whether my guess is right. help me please... thanks a lot before..:shy:
 
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  • #2
songoku said:

Homework Statement


The question actually contains a diagram but i don't understand how to draw it, so i'll try to describe it in words.
A solution contains phenol, acetic acid, aniline and nitrobenzene. Na2CO3 is added into the solution and two layers are formed: aqueous layer A and ethereal layer X. Then NaOH is added into ethereal layer X, two layers are formed: aqueous layer B and ethereal layer Y. At last, dilute HCl is added into ethereal layer Y and aqueous layer C and ethereal layer D is formed. The question is, identify the correct combinations of compound A, B, C and D.


Homework Equations





The Attempt at a Solution


I am really weak in organic chemistry. I tried to check the characteristics but i don't get it :cry: well, this is my guess: phenol, acetic acid and nitrobenzene is acidic while aniline is alkaline. so when Na2CO3 is added, it will react with those three and leaves aniline unreacted. then A is aniline. then i got confused :confused: i really don't have any idea. and I'm not sure whether my guess is right. help me please... thanks a lot before..:shy:

Need to see that diagram
 
  • #3
Start by listing your pKa's for everything and then determine the pH of bicarb solution.
 

1. How can I differentiate between phenol and acetic acid?

The simplest way to differentiate between phenol and acetic acid is by conducting a smell test. Phenol has a distinct medicinal, carbolic smell while acetic acid has a pungent, vinegar-like smell. Another way is to perform a solubility test. Phenol is soluble in water, but acetic acid is not. You can also use a pH test strip to determine the acidity of the solution. Phenol has a pH of around 5-6, while acetic acid has a pH of around 2-3.

2. How can I distinguish between aniline and nitrobenzene?

Aniline and nitrobenzene have distinct physical properties that can help differentiate them. Aniline is a clear, colorless liquid while nitrobenzene is a yellowish liquid. You can also perform a solubility test, as aniline is soluble in water, but nitrobenzene is not. You can also use a pH test strip to determine the acidity of the solution. Aniline has a pH of around 5-6, while nitrobenzene has a pH of around 3-4.

3. What chemical tests can I perform to differentiate these four compounds?

Aside from the solubility and pH tests mentioned above, you can also use a ferric chloride test to differentiate these compounds. Phenol will produce a violet color, acetic acid will produce a yellow color, aniline will produce a green color, and nitrobenzene will produce an orange color. You can also use a bromine water test, as phenol and aniline will decolorize the bromine water, while acetic acid and nitrobenzene will not.

4. Can I use spectroscopy to differentiate these compounds?

Yes, you can use spectroscopy to differentiate these compounds. Phenol will show peaks at around 3200-3500 cm-1 and 1600-1500 cm-1 in an infrared spectrum, while acetic acid will show a peak at around 1700 cm-1. Aniline will show peaks at around 3300-3200 cm-1 and 1600-1500 cm-1, and nitrobenzene will show a peak at around 1500 cm-1. In a nuclear magnetic resonance (NMR) spectrum, phenol will show a peak at around 7-8 ppm, acetic acid will show a peak at around 2 ppm, aniline will show peaks at around 7-8 ppm and 2-3 ppm, and nitrobenzene will show a peak at around 2-3 ppm.

5. What other techniques can I use to differentiate these compounds?

Aside from the chemical tests and spectroscopy mentioned above, you can also use thin-layer chromatography (TLC) to differentiate these compounds. Each compound will have a different Rf value when run on a TLC plate. You can also use gas chromatography-mass spectrometry (GC-MS) to analyze the compounds and their fragmentation patterns. Finally, you can also perform melting point and boiling point tests, as each compound will have different melting and boiling points.

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