Chem 103 Lab Final Exam with Complete Solutions

Chem 103 Lab Final Exam with Complete Solutions **What physical properties were used to differentiate between alkanes and alkenes?** Boiling points and density. **What color does potassium permanganate turn in Baeyer's test?** Purple. **What color does bromine appear in the bromine test?** Yellowish-orange. **Which type of hydrocarbon gives a positive result in Baeyer's and/or bromine test?** Alkenes. **What solvent was utilized for the extraction of curcumin?** Isopropyl alcohol. **What percentage of curcumin is typically found in turmeric?** Approximately 3-5%. **In laboratory applications, what role can curcumin play?** It can serve as a pH indicator. **What instruments were employed in the laboratory experiment? Briefly describe their components.** Spec 20 spectrophotometer. **What is the maximum wavelength of curcumin observed in the UV/Vis spectrum?** 425 nm. **Which chemical test was used to distinguish between aldehydes and ketones?** Tollens' test. **Which of the following will react with Tollens' reagent: ketone or aldehyde?** Aldehyde will react, but ketone will not. **What does a positive Tollens' test result look like?** Formation of a silver mirror. **In what physical state were the unknown ketones/aldehydes in the experiment?** Liquid. **What is the derivative formed from ketones/aldehydes called?** 2,4-dinitrophenylhydrazone. **Which reagent was used to synthesize the ketone/aldehyde derivative?** 2,4-dinitrophenylhydrazine. **Describe the physical state and color of the derivative formed.** Solid and yellow. **What compound was extracted from the aspirin tablet, and what solvent was used for the extraction?** Acetylsalicylic acid (aspirin); solvent used was ethanol. **What acid was employed in the hydrolysis of acetylsalicylic acid to salicylic acid?** Diluted hydrochloric acid (20%). **At what temperature was the hydrolysis reaction performed, and what byproduct was produced?** Reaction temperature: 60 degrees