Question

On a Fisher-John Melting Point Apparatus, how should the sample be prepared?

a) In a powdered form
b) As a thin film
c) As a large crystal
d) In solution form

Answer 1

Samples for a Fisher-John Melting Point Apparatus must be prepared in powdered form for accurate melting point measurement.

Step-by-step explanation:

When preparing a sample on a Fisher-John Melting Point Apparatus, the sample should be in powdered form. This allows for a more uniform heating and a clearer determination of the melting point. Large crystals or samples in solution form do not heat evenly, which can cause inaccuracies in the measurement. Similarly, thin films are not suitable for this instrument.

To ensure the accuracy of a melting point determination, it is essential that the sample is dry and finely ground into a powder before it is loaded into the thin melting-point capillary tube. Only a small amount of the substance, usually a couple of milligrams, is needed for the test. Once the sample is loaded properly, you then proceed to use the Fisher-John Melting Point Apparatus according to its operating instructions to accurately determine the melting point of the sample.