A student was performing a separation of a mixture of organic compounds. The final step of the process involved a filtration of
the analyte from an aqueous solution. After drying the filtered solid for a very short period time, they took the melting point of the compound. The measured melting point range of the compound was 106 – 113.8 0C, while the literature melting point of the compound was 122.3 0C. The above scenario is a very common one in organic labs. 1. Do you think their sample was pure?
2. If not, then what do you think could be the source of error.
3. How do you think this error can be minimized?
3) The solvent should be evaporated properly before washing and drying the analyte
Explanation:
During separation of organic compounds, solvents are used. These solvents are able to contaminate the analyte and lead to a large difference in melting point of solids obtained.
However, the error can be minimized by evaporating the solvent before washing, drying and melting point determination of the solid.
Dispersion forces increases with increase in relative molecular mass. The specie having the greater relative molecular mass definitely has greater dispersion forces. A rough estimation of the relative molecular masses of the species stated in the answer will reveal this fact.
