Asian_History

CHEM122PRACTICEPROBLEMS 1 One step in the production of sulfuric acid is 2 SO2(g) + O2(g) 2 SO3(g) a) Why is this reaction carried out using air as the source of oxygen rather than pure oxygen' b) From the following standard enthalpies of formation, predict whether this reaction is exothermic or endothermic. Show your reasoning clearly. ∆Hf0 SO2(g) = -297kJ/mol; ∆Hf0 SO3(g) = -791kJ/mol 2 Consider the reaction HCl(g) + F2(g) HF(g) + ClF(g) a) Use “periodic table reasoning” to predict whether this reaction will release heat (exothermic) or absorb heat (endothermic). Explain clearly b) Use the following “average bond energies” (in kJ/mole)to verify or disprove your prediction Cl-F 256; F-F 158; H-Cl 431; H-F 565 3. First ionization energies [M(g) M+(g) + e-(g) where M represents an atom of an element) generally increase going to the right in each row of the periodic table; e..g. in the third row Na 494kJ/mol to Cl 1255kJ/mol a) Explain this trend using “periodic table reasoning.” b) One exception to the above trend occurs in the third row where Al has a much lower ionization energy than magnesium. Suggest a reason for this. 4. The following species have the same number of electrons: Cd, In+, Sn2+. a) write a condensed electron configuration for each [Rare Gas ns#np#...] How do they differ' b) How many unpaired electrons in each' 5 Write the Lewis structures for ONF and for the BrO- ion . Explain your method 6, Draw the Lewis structure for the oxalate ion C2O42- which has a carbon-carbon bond in the center with two oxygen atoms bonded to each oxygen. Include resonance structures if any are possible. 7. Predict the shape of the thionyl chloride molecule; SOCl2. S is the central atom 8. Write the Lewis structures and predict the approximate bond angles for SbCl5 and the nitrite ion, NO2- 9.Write the Lewis structure and predict whether each of these molecules will be polar or nonpolar: CHCl3 and SF4 Explain 10.Arrange the following three ionic compounds in order of expected increase in lattice energy ( converting an ionic solid to separate gaseous ions, Sodium chloride NaCl, rubidium chloride RbCl, and magnesium chloride MgCL2 Explain 11. One way to “understand” the pattern of the Periodic Table of the Element s is to use the rules governing quantum numbers n, l, & ml “discovered” the 1920’s. a ) Which of the following subshells can exist in an atom' 1p 4d 3s 2d 5g. Explain b) Which of the following subshells can not exist' 3d 4d 3f 5f 2p. Explain. KS