Identification Of An Unknown Solid By Melting Point

Ð'ҐÐ'o. Summary of Results

A. Melting point of Benzoic Acid

Temperature (Ð'ÐŽÐ"†C) Observation

Unmelted White salt

First liquid appear point 122 Grainy and shiny white

Becoming all liquid 125 Clear

B. Melting point of unknown #42

1st trial

Temperature (Ð'ÐŽÐ"†C) Observation

Unmelted Shiny light yellow crystal

First liquid appear point 99 Grainy yellow

Becoming all liquid 101 Clear

2nd trial

Temperature (Ð'ÐŽÐ"†C) Observation

Unmelted Shiny light yellow crystal

First liquid appear point 95 Grainy yellow

Becoming all liquid 97 Clear

C. Melting point of mixture (Unknown + Benzil)

Temperature (Ð'ÐŽÐ"†C) Observation

Unmelted Shiny light yellow crystal

First liquid appear point 95 Grainy yellow

Becoming all liquid 97 Clear

Ð'ҐÐ'±. Discussion of results

Assessment of sample purity for a known substance. By comparing observed range for an actual sample to the known range for a pure sample, I can tell whether my actual sample is pure or contaminated (the range is depressed and broadened). So, In part A, melting point of benzoic acid was observed in range 122 to 125 Ð'ЁÐ'¬C. By comparing melting point of benzoic acid (121 Ð'ЁÐ'¬C) with result from part A, the result is little higher than the pure melting point. So I can tell it is little contaminated.

Identification of an unknown sample (compare its observed melting range with known compounds). Unknown #42 was found to have a melting range of 99 to 101 Ð'ЁÐ'¬C in 1st trial and 95 to 97 Ð'ЁÐ'¬C in 2nd trial. The only one given pure compounds with similar melting ranges was benzil (94~95 Ð'ЁÐ'¬C). The mixture of the unknown and benzil produced

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