The melting point of pure benzoic acid and pure naphthol are 122.5 *C and 123 *C respectively. You are given a pure sample that is known to be either pure benzoic acid or 2- naphthol. Describe a procedure you will use to determine the identity of the sample.

If you react the unknown sample with a weak aqueous solution of sodium bicarbonate, you will get one of two reactions:

a) formation of sodium benzoate if the sample had been benzoic acid
b) formation of an ether, if the sample had been 2-naphthol (likely in a separate layer on top).
Then, then a simple contuctivity test (ohmmeter) will either confirm ions (sodium benzoate solution), or not (ether from naphthol reaction).

Bob pursley, that seems like too much work.

FT-IR: Look for a peak at 1700, which would distinguish it from naphthol if it is Benzoic acid. Naphthol does not have a carbonyl group.

UV-VIS: Take the absorbance of the compound. If 2-naphthol, you should see a red shift in absorbance, somewhere around 250 or 260nm. Benzoic acid absorbs light at around 230 to 240nm.

UV-VIS: Take the absorbance of the compound. If 2-naphthol, you should see a red shift in absorbance, somewhere around 250 or 260nm. Benzoic acid absorbs light at around 230 to 240nm. 230nms to 240nm is on the high end.

I apologize. 2-naphthol should see a greater shift close to about 270 to 300 nm.

To determine the identity of the given sample, which can be either pure benzoic acid or 2-naphthol, you can rely on a technique called melting point determination. The procedure involves comparing the melting point of the unknown sample to the known melting points of pure benzoic acid and pure naphthol.

Here is a step-by-step procedure to determine the identity of the sample:

1. Prepare a melting point apparatus: Set up a melting point apparatus, which typically consists of a heating block, a temperature controller, and a magnifying lens to observe the sample during melting.

2. Obtain a known sample of pure benzoic acid and pure naphthol: To compare the melting points accurately, have samples of known pure benzoic acid and pure naphthol ready. These samples should have recorded melting points of 122.5 *C and 123 *C, respectively.

3. Grind the unknown sample and pure standards: Using a mortar and pestle, grind a small amount of the unknown sample and the pure benzoic acid and naphthol separately. Ensure that all samples are adequately pulverized into fine powder.

4. Take a small portion of the unknown sample: With a micro spatula or a weighing paper, measure a tiny amount of the unknown sample. It is crucial to use the same mass for all tests to ensure consistency.

5. Fill the melting point capillary tube: A thin glass capillary tube is used to hold the sample during melting. Fill the capillary tube with the unknown sample by gently tapping it onto a small pile of the sample powder.

6. Repeat step 5 with pure benzoic acid and pure naphthol: Fill two separate capillary tubes using pure benzoic acid and pure naphthol using the same method as described in step 5.

7. Insert the capillary tubes into the melting point apparatus: Carefully place each capillary tube, one by one, into separate holes in the heating block of the melting point apparatus. Ensure that the tubes are inserted at the same depth and secured in place.

8. Slowly raise the temperature: Gradually increase the temperature of the heating block, monitoring the samples through the magnifying lens. Observe any changes that occur as the temperature rises.

9. Record the melting points: Note the temperature at which each of the samples starts to melt (first sign of liquid) and fully melts (completely liquefied). These temperature ranges are the melting points.

10. Compare the melting points: Compare the melting points of the unknown sample with the known melting points of pure benzoic acid and pure naphthol. If the melting point of the unknown sample matches closely with either of the known melting points, you can identify the unknown sample accordingly.

By comparing the melting points, you can confidently determine whether the given sample is pure benzoic acid or 2-naphthol.