Uncovering the Mystery of Acetanilide and Caffeine Melting Point Range

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SUMMARY

The melting point range of a 25% acetanilide and 75% caffeine mixture was recorded between 198 and 240 degrees Celsius. Acetanilide has a melting point of 114.3 degrees Celsius, while caffeine melts at 238 degrees Celsius. The observed range suggests potential interactions between the two compounds, possibly due to caffeine coating acetanilide or dissolution effects. Experimental factors such as measurement consistency and cooling intervals may also contribute to the variability in melting point readings.

PREREQUISITES
  • Understanding of melting point concepts and definitions
  • Familiarity with acetanilide and caffeine chemical properties
  • Knowledge of phase diagrams in mixed systems
  • Experience in conducting and interpreting melting point experiments
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  • Research the effects of composition on melting point in binary mixtures
  • Study the principles of phase transitions in solid-liquid systems
  • Learn about the techniques for measuring melting points accurately
  • Investigate the solubility of caffeine in acetanilide and its impact on melting behavior
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Chemistry students, laboratory technicians, and researchers studying phase behavior in organic compounds will benefit from this discussion.

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I have a sample of 25 % acetanilide with 75 % caffeine.


I record a melting point range of 198 - 240 degrees celsius



acetanilide's melting point is 114.3
caffeine's melting point is 238

What would cause this huge experimental range?

My thinking is that the acetanilide is covered in caffeine, and finally melts, at a higher temperature. I am not really sure about this, please help!
 
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How do you define melting?

In mixed systems, particularly metal alloys, there is often a liquid and solid phases, and the solid and liquid phases may have different compositions.

Is the composition constant? In other words, were you measuring one mixture with that composition? How many measurements did you make? If multiple measurements, did you allow for cooling in between?

Perhaps there is a dissolution of caffeine into the acetanilide.
 

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