QUIZ 1 – 50 points
NAME:___________________________
1. (30 points) Calculate mass in gram of AlCl3 needed to equivalently react with potassium naphthalenide which prepared from 0.446 g of naphthalene and 0.137 g of potassium in 5 mL of THF. Balance two reaction equations for full credit. Compound
Molar mass (g/mol)
Density (g/mL)
THF
72.106
0.889
Naphthalene
128.174
Potassium
39.098
Aluminum chloride
133.340
(5 points) (10 points)
(5 points)
K + 0.137 g 3.50 mmol
K+C10H8•C10H8 0.446 g 3.47 mmol 3.47 mmol Limiting reagent
3 K+C10H8•3.47 mmol
+ AlCl3 Al + 3KCl 3.47/3 = 1.157 mmol
+ 3C10H8
1.157x10-3x133.340 = 0.154 g AlCl3
(10 points)
2. (5 points) State reason(s) why you have to prepare potassium naphthalenide inside the glove box. Both potassium and potassium naphthalenide are air- and moisture-sensitive. 3. (5 points) When working with a glove box, your partner opens the chamber lid from outside of the glove box. What will you do before removing your stuff from the glove box? Evacuate and back fill the chamber with N2 three times before opening the inside lid. 4. (5 points) Explain why THF is a good solvent for preparation of potassium naphthalenide. THF is an inert solvent and will not react with potassium naphthalenide. 5. (5 points) External magnetic field and electromagnetic radiation are applied to the sample when obtaining ESR spectrum. What region of electromagnetic radiation is used in ESR? Microwaves