Chem 111 Summer 2013 Key III Whelan

Transcription

1 Chem 111 Summer 2013 Key III Whelan Questin 1 6 Pints Classify each f the fllwing mlecules as plar r nnplar? a) NO + : c) CH 2 Cl 2 : b) XeF 4 : Questin 2 The hypthetical mlecule PY 3 Z 2 has the general classificatin AX 5 E 0 and is fund t be nn plar. Based n this infrmatin what can yu infer as t the relative size f Y when cmpared t Z? Questin 3 In ur discussin n the cnsequences f mlecular plarity. The depictin n the left was used t discuss: Detergents Water disslving KMnO 4 Fabric sfteners Chelating therapy Questin 4 4 Pints The hybridizatin used t describe the bnding abut the central atm in NOBr is, which makes the apprximate bnd angles in this mlecule degrees. Questin 5 6 Pints Depicted belw is the sigma bnds HCCH. a) The sigma bnd frmed between C1 and C2 is best described as being between the verlap f tw hybrid rbitals. b) The sigma bnds frmed between the hydrgen and carbn is best described as being the verlap f an hybrid rbital n each carbn with the rbital n the hydrgen atms. c) If the pi bnds were t be depicted ne wuld see pi bnd(s). Questin 6 The bnding in a mlecule is best described using sp3d hybridizatin. The electrn pair gemetry f this mlecule is:

2 Questin 7 Questin 8 Classify each f the cmpunds as sluble (s) r nt sluble (ns): Zinc sulfate: Calcium carbnate: Silver(I) acetate: Write a balanced chemical equatin fr the reactin that ccurs when aqueus slutins f silver(i) nitrate and nickel(ii) chlride are cmbined: = Questin 9 Write the net inic equatin fr the reactin that takes place when aqueus slutins f ammnium sulfide and chrmium(iii) chlride are mixed. = Questin 10 Write a net inic equatin fr the reactin that ccurs when aqueus slutins f sdium hydrxide and perchlric acid are cmbined. = Questin 11 Write a net inic equatin fr the reactin that ccurs when a hydrchlric acid (aq) and chrmium(ii) sulfide (s) are cmbined. = Questin 12 8 Pints A chunk f silver weighing 19.7 grams and riginally at C is drpped int an insulated cup cntaining 76.6 grams f water at C. Assuming that all f the heat is transferred t the water, calculate the final temperature f the water. Heat Capacity : H 2 O = J/g C Ag = J/g C Fr full credit yu must shw wrk. C

3 Questin 13 4 Pints The reactin f irn(iii) xide(s) with hydrgen(g) t frm irn(s) and water(g) prceeds as fllws: Fe 2 O 3 (s) + 3H 2 (g) = 2Fe(s) + 3H 2 O(g) When 56.5 grams f Fe 2 O 3 (s) react with sufficient H 2 (g), 35.0 kj f energy are absrbed. What is the value f H fr the reactin per mle f Fe 2 O 3? Fr full credit yu must shw wrk. kj Questin 14 8 Pints When 0.32g f hydrazine (N 2 H 4 ) is burned in a bmb calrimeter cntaining 600g f water the temperature f the water increases by 1.8 C. Calculate the heat f cmbustin f hydrazine in J.ml -1 Heat Capacities: H 2 O = J/g C Calrimeter = 420 J/ C Fr full credit yu must shw wrk. J/ml

4 Questin 15 4 Pints Given the standard enthalpy changes fr the fllwing tw reactins: (1) 2 C(s) + 2 H 2 (g) = C 2 H 4 (g)... ΔH = 52.3 kj (2) 2 C(s) + 3 H 2 (g) = C 2 H 6 (g)...δh = kj what is the standard enthalpy change fr the reactin: (3) C 2 H 4 (g) + H 2 (g) = C 2 H 6 (g)...δh =? Fr full credit yu must shw wrk. kj Questin 16 4 Pints Using standard heats f frmatin given belw, calculate the standard enthalpy change fr the fllwing reactin. 2NO(g) + 2H 2 (g) = N 2 (g) + 2H 2 O(l) H f: NO(g) = 90.3 kj.ml -1 H 2 O(l) = kj.ml -1 kj Questin 17 4 Pints A ml sample f O 2 gas is cnfined in a 21.0 liter cntainer at 16.2 C. If the temperature f the gas sample is decreased t C, hlding the vlume cnstant, the pressure will decrease because: Chse all that apply With higher average speeds, the mlecules hit the walls f the cntainer mre ften. At lwer temperatures mlecules have lwer average speeds. As the average speed increases, the number f mlecule-wall cllisins decreases. With lwer average speeds, n average the mlecules hit the walls f the cntainer with less frce.

5 Questin 18 5 Pints Yu need t make an aqueus slutin f 0.142M calcium nitrate fr an experiment in lab, using a 250mL vlumetric flask. Hw much slid calcium nitrate shuld yu add? Fr full credit yu must shw wrk. g Questin 19 5 Pints Fr the fllwing reactin, mles f carbn disulfide are mixed with mles f chlrine gas. carbn disulfide (s) + chlrine (g) = carbn tetrachlride (l) + sulfur dichlride (s) What is the maximum amunt f carbn tetrachlride that can be prduced? Fr full credit yu must shw wrk and give balanced chemical equatin(s). ml

6 Questin 20 8 Pints Fr the fllwing reactin, 3.86 grams f xygen gas are mixed with excess nitrgen gas. The reactin yields 5.81 grams f nitrgen mnxide. nitrgen (g) + xygen (g) = nitrgen mnxide (g) What is the percent yield fr this reactin? Fr full credit yu must shw wrk and give balanced chemical equatin(s). Questin Pints 47.2mL f 0.113M hydrbrmic acid is added t 21.4mL f calcium hydrxide, and the resulting slutin is fund t be acidic. 29.8mL f M sdium hydrxide is required t reach neutrality. What is the mlarity f the riginal calcium hydrxide slutin? Fr full credit yu must shw wrk and give balanced chemical equatin(s). % M

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