Post-lab A

Emily Ebel Tues. 8 AM Experiment A TA: Emma Downs Post-lab Questions 1. Unknown A melting range: 79.9-81.5° C 2. Unknown + …

Observed Melting Point Range (° C) 59.4-69.8 49.8-63.7 80.5-82.2

Naphthalene Phenylacetic acid Vanillin

3. Unknown A is vanillin. The melting point of vanillin is 81-83° C, according to Sigma Aldrich. When the unknown was mixed with vanillin, the melting point remained in vanillin’s literature melting range. If the unknown was another compound, the observed melting point range of the mixture would have been lower and broader, as it was in the mixtures of naphthalene and phenylacetic acid with the unknown. (The identity of the unknown was originally narrowed down to naphthalene, phenylacetic acid, and vanillin based on its melting point range when heated alone; all of these compounds have a melting point of approximately 80° C.) 4. Vanillin Structure

Melting Point

Molecular Formula

Molecular Weight

Price (Aldrich)

81-83° C

C8H8O3

152.15

100 g, ≥97%: $107

(Source: sigmaaldrich.com) 5. NFPA Rating Fire: 0 Reactivity Hazard: 0 Health Hazard: 0

Acute Toxicity: LD50 was 1,580 mg/kg for a rat, administered orally. Caused coma.