Organic Chemistry Laboratory I (X36.1A) PRE-LAB QUIZ for EXPERIMENT 9
Organic Chemistry Laboratory I (X36.1A)PRE-LAB QUIZ for EXPERIMENT 9Name ___________________________1. In this experiment, you will convert sodium naproxen, the active ingredient in Aleve®, tonaproxen. Look up the structures of these compounds and write them in the spaces below tocomplete the equation for the reaction that you will perform.2+ H2SO4 –––>2sodium naproxen2. In this experiment, you will measure the melting point ofnaproxen. Look up the reported melting point of naproxenonline so you will know what melting point to expect in lab.+ Na2SO4naproxenMelting point ofnaproxen is_____________°C3. An Aleve® tablet contains 220 milligrams of sodium naproxen. Use the chemical equationabove to calculate the maximum weight of naproxen that can be obtained from 220 mg ofsodium naproxen.4. According to the textbook (page 253), the solubility of naproxen in 95% ethanol is 1 g/25 mL.Based on that solubility, how many milliliters of 95% ethanol would be needed to dissolve themaximum amount of naproxen that can be recovered from 220 mg of sodium naproxen?NOTE: 1 g/25 mL is probably room temperature solubility. Naproxen should be more soluble in hot ethanol.5. Question 5 on page 256 of the textbook asks why sulfuric acid is used in this experimentrather than acetic acid. To see why acetic acid is not used, calculate the equilibrium constant forthe reaction (shown below) of sodium naproxen with acetic acid. Acetic acid has pKa 4.75 andnaproxen has pKa 4.15.(NOTE: See pgs. 19-20 in the textbook for information on finding equilibrium constants from pKa values.)Na+C14H12O3+ CH3COOHsodium naproxenacetic acid⇌ HC14H12O3naproxen+ CH3COO– Na+sodium acetate6. In Part III of Experiment 9, the optical rotation of naproxen is measured in a polarimeter. Ifthe observed rotation ( αD ) from a solution prepared by dissolving 500 mg of naproxen in 25 mLof 95% ethanol and measured in a sample tube 15.0 cm (1.50 dm) in length is +1.98°, what is thespecific rotation, [α]D, of naproxen?NOTE: We will not do Part III of Experiment 9.