Mixed Melting Points Essay example

853 Words Sep 14th, 2011 4 Pages
Organic chemistry 201 | Mixed Melting Points | Determination of an Unknown Solid | | [Type the author name] | 9/15/2011 |

Purpose :
The main purpose of this experiment was to identify an unknown compound/substance by performing multiple experimental melting point tests. Pure and impure solids were tested to see what affect pureness/impureness had on a melting point.
The melting point of a solid can be used to determine the purity of the solid. Pure samples usually have identical or similar melting points. Given this information, the identification of an unknown solid could be determined by comparing its experimental melting point to an accepted literature value of a known substance. Pure solids always have
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To determine the identity of the unknown substance, a mixture of cinnamic acid and the unknown was made, as well as a mixture of urea and the unknown substance. The melting points of these mixtures were obtained. The resultant melting points allowed for accurate identification of the unknown substance.
Compounds and Their Melting Points Compound/Mixture | Melting Point Range (Trial 1) | Melting Point Range (Trial 2) | Unknown | 132°-134° | 132.4°-134.2° | Cinnamic Acid | 133.1°-134.4° | 133.5°-135.8° | Urea | 131.7°-135.1° | 131.4°-134.6° | Cinnamic acid: Urea mixture | 101.0°-128.2° | 98. °1-129.8° | Urea: Unknown mixture | 99.6°-106.7° | 98.1°-107.4° | Cinnamic Acid: Unknown mixture | 131.3°-133.2° | 129.8°-134.6° |
Interpretation of Results/Data:
The pure forms of the unknown, cinnamic acid, and urea were all found to have high melting points in the 130s as well as narrow melting point ranges. The mixtures of the various compounds were all noted to have lower melting points and very wide melting point ranges. This data was to be expected. It proved the theory that pure compounds have higher melting points and narrow melting point ranges, and that impure/mixed compounds have lower melting points and wider melting point ranges.
The unknown compound was either cinnamic acid or urea. To determine which compound it was, mixed melting points were used. The unknown compound was determined by finding the boiling

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