CHEM121-EXAMIII-practice00

CHEM121-EXAMIII-practice00 - Name_ Chemistry 121 Exam III...

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Name_____________________________ Chemistry 121 Exam III Spring 2009 100 points 1. (18pts/6pts each) a. The value of ∆H o for the following reaction is -482 kJ. Determine the amount of heat (in kJ) exchanged with the surroundings when 14.0g of CO(g) completely reacts. 2CO(g) + O 2 (g) ----------> 2CO 2 (g) b. 65.0g of water at 69.0 o C is added to an unknown amount of water at 22.0 o C. The final temperature is 31.0 o C. How many grams of water were there initially at 22.0 o C? [Specific heat water = 4.184J/g o C]
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c. Write quantum numbers for the orbital diagram representation of the valence electrons below : (Use “P” for your electrons) [Ne] _______ _______ ______ _______ 3s 3p electrons n l m l m s 2. (8pts) Draw the Lewis Dot Structure for CH 3 OCH 3 CaCl 2
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3. (10pts) Applying Hess’s Law, calculate the value of ∆H o for the following reaction: 2N 2 (g) + 5O 2 (g) ---------> 2N 2 O 5 (g) The following thermochemical equations should be used: 2H 2 (g) + O 2 (g) ----------> 2H 2 O(l) ∆H = -571.66kJ N 2 O 5 (g) + H 2 O(l) ------> 2HNO 3 (l) ∆H = -92 kJ N 2 (g) + 3O 2 (g) + H 2 (g) -------> 2HNO 3 (l) ∆H = -348.2 kJ 4 . (12 points) Calculate the standard enthalpy of formation of solid Mg(OH) 2 , given the following data (hint: you must know the definition for an “enthalpy of formation” reaction): 2Mg(s) + O 2 (g) --------------------- 2MgO(s) ∆H = -1203.6 kJ Mg(OH) 2 (s) ----------- MgO(s) + H 2 O(l) ∆H = +37.1kJ 2H 2 (g) + O 2 (g) ----------- 2H 2 O(l) ∆H = -571.7kJ
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5. (52points/2pts each ) Multiple Choice/Short Answer
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CHEM121-EXAMIII-practice00 - Name_ Chemistry 121 Exam III...

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