Chm 150 Exam 2. Chapters 7, 10, and Nomenclature

Name: ___KEY_____________________________ Section: ____________ CHM 150 Exam 2: Chapters 7, 10, and Nomenclature 1. (9 pts) Write the correct formula for the following compounds: a. ammonium fluoride __NH4F______________ b. diphosphorous pentasulfide __P2S5_______________ c. hydrochloric acid __HCl (aq)____________ d. magnesium chlorite __Mg(ClO2)____________ e. iron (III) hydroxide __Fe(OH)3____________ 2. (9 pts) Write the correct name for the following compounds: a. CoP _cobalt (III) phosphide___________ b. SO2 _sulfur dioxide_________________ c. Ag3N _silver nitride__________________ d. CaBr2 _calcium bromide______________ e. HNO3 (aq) _nitric acid____________________ 3. (4 pts) What charge will the following atoms have when they become ions? a. Ca _+2______ b. Cl __-1______ c. K __+1______ d. Ga __+3____ 4. (3 pts) Circle all of the following compounds that are covalent: Li2O N2O3 MnS IBr CaS PF5 _D_ 5. (3 pts) The measure of attraction that an atom has for the electrons in a covalent bond is called a. electron affinity b. ionization energy c. hybridization d. electronegativity e. London forces 6. (4 pts) Indicate the polarity of each covalent bond using an arrow and delta notation ( - or No arrow arrow toward F arrow toward Cl arrow toward Cl H—C N—F Cl—I P—Cl + ): _C_ 7. (3 pts) The electronegativity for H is 2.1 and for Si is 1.8. Based on these values, SiH4 would be expected to a. be ionic and contain H- ions. b. be ionic and contain H+ ions. c. have polar covalent bonds with partial negative charges on the H atoms. d. have polar covalent bonds with partial positive charges on the H atoms. page 1 of 4 Name: ___KEY_____________________________ Section: ____________ _B_ 8. (3 pts) The Lewis structure for phosphine, PH3, has a. 3 bonding pairs b. 3 bonding pairs and 1 lone pair c. 2 bonding pairs and 2 lone pairs d. 4 bonding pairs e. 4 lone pairs 9. (3 pts) Which of the molecules below would have the same Lewis Dot Structure as ClO3- ? Circle all that apply. Hint: You do not need to draw the structures to answer this question. IO3- CO32- BrO3- SO3 SO32- _A_ 10. (3 pts) Which bond should be the longest? a. N – N b. N = N c. N ≡ N d. They should all be the same length. 11. (8 points) Indicate whether each statement is true (T) or false (F). T F Carbon can have an expanded octet. T F In general, triple bonds are stronger than single bonds. T F A molecule with AB3E notation has 3 electron domains and will have trigonal planar geometry. T F Sigma bonds are only found in single bonds. T F Pi bonds are formed from unhybridized s orbitals. T F A triple bond contains 1σ bond and 2π bonds. T F Ice (solid water) is less dense than liquid water. T F Liquids with higher vapor pressures boil at higher temperatures compared with liquids with lower vapor pressures. _C_12. (3 pts) Which answer correctly states the approximate (~) values of the bond angles, a and b, in the ion illustrated below? a. b. c. d. e. a is ~90o and b is ~180o a is ~109.5o and b is ~109.5o a is ~109o and b is ~120o a is ~120o and b is ~109.5o a is ~109.5o and b is ~180o page 2 of 4 Name: ___KEY_____________________________ Section: ____________ 13. (10 pts) Please draw all possible Lewis Dot Structures for IO2- and answer the following questions: 2 lone e- pairs on I, 2 single bonds to O, full octets on each O, brackets with charge ABE notation: __AB2E2__________ Number of electron domains: __4_____ Molecular shape:__bent__________ Is the molecule polar (Circle one)? Yes What is the bond angle?__<109.5o________________ What is the hybridization of the central atom:__sp3______ How many sigma ( ) and pi ( ) bonds are there? ___2_____ ____0____ No 14. (13 pts) Please draw all possible Lewis Dot Structures for SO3 and answer the following questions: 3 resonance structures: 2 single bonds, 1 double bond, complete octets on each O ABE notation: __AB3_____________ Number of electron domains: __3_____ Molecular shape:__trigonal planar___ Is the molecule polar (Circle one)? Yes o What is the bond angle?__120 ________________ What is the hybridization of the central atom:_sp2________ How many sigma ( ) and pi ( ) bonds are there? __3_____ ____1____ No 15. (3 pts) Indicate the hybridization of a central atom with following number of electron (e-) domains: 2 e- domains: _sp____ 5 e- domains: __sp3d___ 6 e- domains: _sp3d2_ 16. (5 pts) Identify the strongest type of intermolecular force in each of the following (London, Dipole-Dipole, Hydrogen Bridging, or Ion-Ion). Use these substances to answer the next 2 questions. NaCl __ion-ion__________ NH3 CO2 CH2O __dipole-dipole___ __London Forces_____ __hydrogen bridging_____ C2H6 __London Forces____ 17. (2 pts) Which of the substances (from the question above) should have the highest boiling point? _NaCl__ 18. (2 pts) Which of the substances (from the same list) should have the highest vapor pressure? __CO2_____ 19. (1 pt) Knowing that bromine is a liquid, chlorine is a gas, and iodine is a solid at room temperature (25°C) and normal atmospheric pressure (1atm), predict what state of matter Astatine (At) should be under those same conditions. Astatine will be a solid. It is larger than I2 and will have stronger forces, therefore if I2 is a solid, At will be as well. page 3 of 4 Name: ___KEY_____________________________ Section: ____________ _A_ 20. (3 pts) The vapor pressure of a liquid increases with an increase in temperature. Which of the following statements best explains this increase? a. The average kinetic energy of molecules is greater, thus more molecules can enter the gaseous state. b. The number of gaseous molecules above the liquid remains constant, but these molecules have greater average kinetic energy. c. The faster-moving molecules in the liquid exert a greater pressure. d. All the molecules have greater kinetic energies. e. The intermolecular forces between the molecules decrease at higher temperatures. _C_ 21. (3 pts) The measure of a liquid’s resistance to flow is a. London forces b. c. d. e. Dipole-Dipole forces viscosity vapor pressure surface tension _B_ 22. (3 pts) When a gas becomes a solid, the phase change is called ________. a. sublimation b. deposition c. vaporization d. freezing e. melting Extra Credit: (5 pts) Draw a phase diagram that meets the following criteria: normal melting point is 10oC, normal boiling point is 50oC, triple point is at 0.5 atm of pressure and 5oC, and the solid phase is more dense than the liquid phase. Label the phases and axes. Indicate approximate pressure (in atm) and temperature (in o C) values on the axes. Will be drawn in class when you get the exams back. It’s too hard to describe or try to draw on a computer!!!! page 4 of 4