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Unformatted text preview: MONTGOMERY COLLEGE Business, Science, Mathematics and Technology Division Germantown Campus Fall, 2010 Chem 101 Name: Exam #3 Multiple Choice — In the blank, write the letter of the best answer. (3% ea.) 1. IfSS.9g. ethanol (sp.ht. 2.438 JIg°C) are heated from -11°C to 58°C, q is: a. -(2.43 8) (55.9) (69) c. (2.438) (55.9) (47) b. —(2-438) (55.9) (47) d. (2.438) (55.9) (69) 2. AH for the process CCLKg) —> C0140) 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 $139.0??? 3. 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 sup-99‘s 4. Which of the following statements is true? a. H mmms > H [Wands for an endothermic reaction b. qsystem is negative if the surroundings transfer heat to the system c. if a chemical reaction system absorbs heat, the temperature increases d. q is positive for an exothermic process e. none of the above is true __ 5. If volume is kept constant, heat of reaction is equal to: a. qP c. AH e. -PAV b- AE d. AT ______ 6. IfAH = -142 H for X + 2Y2 —> 2’ind then what is AH for 922 —> 3X + 6Y2? a. -426 k] d. . + 47.3 k] b. - 284 k] e. none of these 0. + 284 kJ 10. ll. 12. l3. 14. 15. For the reaction below, standard enthalpies of formation are given below the formula for each substance. 5 A -~> 4B + C +78.1 -96 - 113.7 For this reaction, AH will equal a. (-96-113.7)«-(78.1) b. [4(-96) + (-113.7)] - [5(78.1)] c. [5(78.1)] +[4(—96) + (-113.7)] d. [5(78.1)]—[4(—96) + (-113.7)] Which quantum number specifies the orientation of an orbital? a. n c. m, b. E (1. 1118 Which quantum number(s) can never equal zero? a. 11 only c. E and ms b. n and E d, n and InS Which set of quantum numbers is allowed? a. n=3,€=0, m£=1, ms=+1/2 b. n=3,€=0, mt=0, ms=-‘/2 c. n=l,€=1, mt=1, ms=0 d. n=2,£=1,mt=+2,m5=+1/2 The electron configuration 1322522p63 523p64sz3 d104p6 fits all of the following except: a. Br' c. Rb" b. Kr d. Sr+2 An element with exactly 19 electrons in the p subshells is a. 19K C. 35Kl' b. 49111 d. none of the above 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 d. 50 b. 100 e. none of these c. 25 Ifan atom contains 20 electrons in its outer shell, how many subshells in that outer shell are filled to maximum capacity? a. 1 c. 4 b. 3 d. 8 2 16. 17. 18. 19. 20. The electron configuration for 29Cu+1 is a. [Ar]4s13d1 d. [Ar]4sl3d9 b. [Ar]4523 d9 e. none of these 0. [Ar]3d“’ The atom with a negative formal charge in the SCN' ion is : C: :: N: _ a. S c. N b. C d. they all have a negative FC. The number of dots in the Lewis structure for the CgHgOg' ion is a. 8 c. 24 b. 32 d. 57 Which of the following Lewis dot structures is correct? H:i\i:H 312.631. a. H c‘ l.o'. an. :6:él:b°: :§:E::: : 13- II on on d. II S 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 21 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/gOC) at 223°C must be added to an 8 oz. ’ (240 g) cup of cofiee (assume a sp. ht. of4. 184 J/g°C) at 945°C to give a final “drinkable” temperature for the coffee of 830°C? Assume that the coffee is in an insulated container, and show a_ll calculations. (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) a. How many shells in an atom of In are filled? b How many subshells in an atom of In contain their maximum numb er of electrons? c How many electrons in an atom of In are in p subshells and have n=3? (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. fourth shell contains equal numbers of p and d electrons contains only 26 electrons in d subshells fifth period element containing only one d electron 5f subshell is exactly half full last electron in configuration fills the third shell the +1 ion has 5 electrons in the 4d subshell noble gas with electrons in an f subshell HHH memo-pow (2% each) 24. Write the symbol of the best answer in the blank. a. Has highest electron affinity (magnitude); Sn, Si, or S? b. Has smallest atomic radius; 34Se'2, 338W, or 3381‘? c. Has largest magnitude of lattice energy; Ga203, GaN, or A1203? d. 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) (6%) 26. draw the Lewis dot structure. the azide ion, Ng‘ 102+ 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. ...
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This note was uploaded on 11/08/2011 for the course CH 101 taught by Professor Susanbontems during the Fall '11 term at Montgomery College.

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exam_3_blank - MONTGOMERY COLLEGE Business, Science,...

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