Practice Problems

Question: A pressure of 1 atm is the same as A. 101.3 kPa B. 760mm Hg C. 14.7 lb/in2 D. all of these Answer: D

Question: To convert a sample of air into a liquid you would probably have to A. increase temperature, increase pressure B. decrease temperature, increase pressure C. cool it to zero Kelvin D. Forget it. Can't be done. Answer: B

Question: Identfy each type of solid below based on its properties A. A soft solid that melts at 60°C and does not conduct B. Solid beeswax (a soft solid that gradually melts at about 50°C) C. A white solid that melts at 1000°C and whose melt does not conduct electricity D. A solid that conducts electricity, melts at 500°C, and forms long, slippery sheets E. A yellowish solid that melts at 700°C and conducts electricity F. A yellowish solid that melts at 700°C and does not conduct electricity Answers: A. Molecular solid B. Amorphous (no crystal shape, gradual melting) C. Network solid D. Network solid, two-dimensional bond plane E. Metallic solid F. Ionic solid

Question: Answer the following questions. A. Why is NaI(s) very soluble in water, whereas I2(s) has very low solubility? B. Why is the boiling point of CCl4 much lower than the boiling point of CBr4? (Hint: Br is a much larger atom than Cl) C. Arrange these solids in order of boiling point, lowest first: CH3OH, C2H5OH, O2, NaCl. D. Which of the following substances involve hydrogen bonding: HBr, H2O, HCl, HF, NH4, AsH4? Answers: A. NaI is an ionic solid, and strong ion-dipole interactions between the ions and water will dissolve the NaI; I2 is a non-polar molecule, so polar water will not readily dissolve it. B. CBr4 is a larger molecule (because Br is a larger atom) than CCl4, leading to stronger dispersion forces and a higher boiling point. C. O2, CH3OH, C2H5OH, NaCl (because O2 has only dispersion attractions; CH3OH is a small, hydrogen-bonded molecule; C2H5OH is a larger hydrogen-bonded molecule with lower attractive forces; and NaCl is an ionic liquid with very high ion-ion attractive forces). D. H2), HF, and NH4 involve hydrogen bonding (only hydrogens hooked to an O, N, or F create hydrogen bonding).

Question: Identify whether the following compounds are soluble. A. CuI B. Al(OH)3 C. K3PO4 D. CuS E. CH3COONa F. FeSO4 Answers: A. No B. No C. Yes D. No E. Yes F. Yes

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