exam_3_key - Fall 2010 MONTGOMERY COLLEGE Business Science...

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Unformatted text preview: Fall, 2010 MONTGOMERY COLLEGE Business, Science, Mathematics and Technology Division Germantown Campus Chem 101 Name: (451 Exam #3 0439. 6% Melvin? Multiple Choice _-’In the blank, write the letter of the best answer. (3% ea.) 4L1. It'55.9g. ethanol (sp.ht. 2.438 JIg°C) are heated from -11°C to 58°C, q is: a. -(2.438) (55.9) (69) c. (2.438) (55.9) (47) b. (2.433) (55.9) (47) d. (2.433) (55.9) (69) AH for the process (10%) —> CCLKI) is: positive and the process is endothermic negative and the process is endothermic positive and the process is exothermic negative and the process is exothermic more than one of the above are correct 993-9375” When glycerine and potassium permanganate are combined, the mixture ignites. Therefore: q and AH are both negative q is negative and AH is positive q and AH are both positive AH is negative and q is positive none of the above $3?“ng Which of the following statements is true? H reactants > H products for an endothermic reaction qustem is negative if the surroundings transfer heat to the system if a chemical reaction system absorbs heat, the temperature increases q is positive for an exothermic process none of the above is true 99.0.95?» vaolurne is kept'constant, heat of reaction is equal to: a. qp 6. AH e. -PAV b. AE d. AT IfAH = -142 kit for X + 2Y2 —) 322, then What is AH for 922 —~> 3X + 6Y2? a. — 426 id (1. + 47.3 k] b. - 284 k] e. none of these 0. + 284 k3 For the reaction below, standard enthalpies of formation are given below the formula for each sub stance. 5 A —> 4 B + C +781 -96 - 113,7 For this reaction, AH will equal a. (~96 - 113.7) — (78.1) b. [4(-96) + (-113.7)] - [5(78.1)] c. [S(78.1)] +[4(-96) + (-113.7)] d. [5(78.1)]_—[4(-96) + (-113.7)] Which quantum number specifies the orientation of an orbital? mt ms flandrns a. n c. b. E d. Which quantum number(s) can never equal zero? a. 11 only c. b.. n and f d. n and mS Which set of quantum numbers is allowed? a. n=3,€=0, m,=1, m5=+1/2 n=3, EEO, m£=0, ms=-1/2 b. c. n=1,£=1, mt=1, m5=0 d. n=2,£=1, mt=+2,ms=+‘/2 The electron configuration 15255221363 sz3p64s23 d1°4p6 fits all of the following except: a. Br' 0. Rb‘ b. Kr d. Sr+2 An element with exactly 19 electrons in the p subshells is a. 19K 0. .1st lo. 49111 Which of the following types of electromagnetic radiation has the highest frequency? a. radar c. microwave b. radio d. visible What is the maximum number of electrons that can be in the fifth shell of an atom? a. 5 b. 100 - c. 25 Ifan atom contains 20 electrons in its outer shell, how many subshells in that d. none of the above d. 50 e. none of these outer shell are filled to maximum capacity? a. 1 b. 3 c. 4 d. 8 2 The electron configuration for ngu+1 is a. [Ar14s‘3d1 d. [Ar]4sl3d9 b. [Ar]4sz3d9 e. none of these c. [Ar]3dm 0g 17 The atom with a negative formal charge in the SCN' ion is 2C: 1: N: _ a. S c. N b. C (1. they all have a negative EC. C 18 The number of dots in the Lewis structure for the CzHaOz- ion is a, 8 c. 24 ' b. 32 d. 57 OK 19 Which of the following Lewis dot structures is correct? Elma. a_ H Q '. .' ' . . ' ."zéizii: '§:Ef::: . b. I o n n a u d. o I S g 5 20. Given the following electronegativities, which of the single covalent bonds below is the most polar? Element: 0 B S H Electronegativity: 3.5 2.0 2.5 2.1 a. S-0 (1. B—S b. H-B e. H—S c. H—O 4 (6 %) 21. What mass, in grams, of silver (sp. ht. 0.235 J/g°C) at 223°C must be added to an 8 oz. (240 g) cup of coffee (assume a sp. ht. OH. 184 J/g°C) at 945°C to give a final “drinkable” temperature for the coffee of 880°C? Assume that the coffee is in an insulated container, and show a_ll calculations. 1 '— fi'ubo with) (e. zesféflgmgoc) ; — (2% 8304. ISM—33%) (We) (99.3%. “(9.8% IS‘HJMAS: @327 AM 2 2 . a (7%) 22. Write the complete electron configuration for indium (atomic number 49). (3%) Then use your electron configuration to answer the questions below. (1% each) [allelQPg'bj a? fiazadbqpbs 13 LlcilmS‘P' 51,. 3 How many shells in an atom of In are filled? b. it) How many subshelis in an atom of In contain their maximum number of electrons? c C: How many electrons in an atom of In are in p subshells and have n=3? cl. 1 | How many subshells in an atom of In contain electrons? (1% each) 23. Without writing any electron configurations give the symbol of the element which best fits each of the following descriptions. Rik fourth shell contains equal numbers of p and d electrons 0A. contains only 26 electrons in d subshells . I fifth period element containing only one d electron Cam 5f subshell is exactly half fiill '5.va last electron in configuration fills the third shell Tc. (who the +1 ion has 5 electrons in the 4d subshell g. [3 D noble gas with electrons in an f subshell was» .o-n .ch (2% each) 24. Write the symbol of the best answer in the blank. a. 5 Has highest electron affinity (magnitude ; Sn, Si, or S? b. Sr“ Has smallest atomic radius; 34Se' , 3:er+ , or 3381‘? c. .GoJO Has largest magnitude of lattice energy; Ga203, GaN, or A1203? d. “a Has the lowest electronegativity; Mg, N, or Br? (3% each) 25. For each of the following, a) determine the total number of valence electrons and b) draw the Lewis dot structure. the azide ion, NE) 102G) ‘1) 5(5)“: lbwe— a) [LC1)\+hz(b)-l ‘e \ngfla/me' b) _ u i. .. + u u :O—I=O.’ (:NZNZM: [ N (6%) 26. Consider the NCO' ion, which has 16 valence electrons. Assuming the presence of two double bonds between the central atom and the terminal atoms, use the concept of formal charge to determine which element is the central atom in the ion. In other words, calculate formal charges for all atoms considering all possibilities as the central atom, and see which is favored on the basis of formal charge. Show all your work, and give a. brief explanation for your choice. ) e" S q (a Li g b g b L‘ fiwfiefie' (0 tr (a J: i E f; j E’. FL. ——\_ o o —2, +) o “I +2 ~7, ...
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exam_3_key - Fall 2010 MONTGOMERY COLLEGE Business Science...

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