Melting Point Determinations
1. Melting range of impure vanillin
2. Melting range of recrystalized vanillin
3. Melting range of 50% recrystallized vanillin + 50% phenyl carbonate
What is your question about this Lab? It appears it is asking you about your results.
1) impure anything should be depressed and/or broad compared to literature melting range
2) pure anything should be at the literature melting range
explain the effect of phenyl carbonate when it mixed with recrystallized vanillin
To determine the melting point of a substance, you will need a few key pieces of equipment: a melting point apparatus or a melting point capillary tube, a heating source (such as a Bunsen burner or a hot plate), and a thermometer. Here's how you can determine the melting points of the substances mentioned:
1. Melting range of impure vanillin:
- Prepare a small amount of the impure vanillin by crushing it into a fine powder.
- Take a clean melting point capillary tube and fill it with the powdered impure vanillin, leaving a small column of air at the top.
- Place the capillary tube with the sample into the melting point apparatus or attach it to a thermometer with a rubber band, ensuring the sample is fully immersed in the heating medium.
- Gradually heat the sample, either by increasing the temperature of the apparatus or by heating it over a flame (be careful not to heat it too quickly).
- Observe the sample continuously until you notice a change in appearance, like melting or changes in color.
- Record the temperature range over which the sample transitions from solid to liquid. This range is known as the melting range of the impure vanillin.
2. Melting range of recrystallized vanillin:
- Follow the same procedure as described for the impure vanillin, but this time, use recrystallized vanillin.
- Recrystallization involves dissolving the impure vanillin in a suitable solvent (like ethanol) and allowing it to slowly cool, resulting in the formation of purified vanillin crystals.
- Collect the purified vanillin crystals, dry them, and then fill the capillary tube with the dry crystals.
- Perform the melting point determination as explained above.
- Record the temperature range over which the recrystallized vanillin transitions from solid to liquid. This range is known as the melting range of recrystallized vanillin.
3. Melting range of 50% recrystallized vanillin + 50% phenyl carbonate:
- Mix 50% of the recrystallized vanillin crystals and 50% of phenyl carbonate by weight.
- Fill a capillary tube with the mixture, leaving some empty space at the top.
- Perform the melting point determination as described above.
- Record the temperature range over which the mixture transitions from solid to liquid. This range is known as the melting range of the 50% recrystallized vanillin + 50% phenyl carbonate mixture.
By comparing the melting ranges obtained for each sample, you can analyze the purity and identity of the substances. Pure compounds tend to have a narrow melting range, while impure or mixed substances typically have broader melting ranges.