spring midterm 2006

spring midterm 2006 - CHEM 14B Instructor: Dr. Laurence...

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1 CHEM 14B YOUR NAME ................................ Instructor: Dr. Laurence Lavelle I D # ............................... SPRING 2006 MIDTERM (Total number of pages = 9) (Total points = 120) (Total time = 110 mins) YOUR DISCUSSION SECTION ...................................... YOUR TA …………………………… Write in pen. Show all your work. Check your units and significant figures. Think Clearly. Good Luck.
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2 Do not write on this page. QUESTION SCORE 1 2 3 4 5 6 7 TOTAL
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3 Q1. Calculate the reaction enthalpy for the synthesis of hydrogen chloride gas (12pt) H 2 (g) + Cl 2 (g) HCl(g) from the following data: NH 3 (g) + HCl(g) NH 4 Cl(s) H ° = –176.0 kJ N 2 (g) + 3 H 2 (g) 2 NH 3 (g) H ° = –92.22 kJ N 2 (g) + 4 H 2 (g) + Cl 2 (g) 2 NH 4 Cl(s) H ° = –628.86 kJ Ans: Balance the reaction: H 2 (g) + Cl 2 (g) 2 HCl(g) 2pt 2 NH 4 Cl(s) 2 NH 3 (g) + 2 HCl(g) H ° = 2(176.0) kJ 2pt N 2 (g) + 4 H 2 (g) + Cl 2 (g) 2 NH 4 Cl(s) H ° = –628.86 kJ 2pt 2 NH 3 (g) N 2 (g) + 3 H 2 (g) H ° = 92.22 kJ 2pt H 2 (g) + Cl 2 (g) 2 HCl(g) H ° = -184.6 kJ 4pt -1sf -1units
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Q2. The reaction of 1.40 g of carbon monoxide (CO) with excess water (H 2 O) vapor to produce carbon dioxide (CO 2 ) and hydrogen (H 2 ) gases in a bomb calorimeter causes the temperature of the calorimeter assembly to rise from 22.113 ° C to 22.799 ° C. The calorimeter assembly is known to have a total heat capacity of 3.00 kJ . ( ° C) 1 . (20pt) (a) Write a balanced equation for the reaction. CO(g) + H 2 O(g) CO 2 (g) + H 2 (g) 1pt 1pt 1pt 1pt (b) Calculate the internal energy change, U , for the combustion of 1.00 mol CO(g). Bomb calorimeter means volume is fixed. Therefore, w = 0. 2pt U = q + w Need to find q . Use q = C T 2pt First work out how much heat was released on burning 1.40 g of carbon monoxide.
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This note was uploaded on 04/26/2008 for the course CHEM 14B taught by Professor Lavelle during the Spring '01 term at UCLA.

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spring midterm 2006 - CHEM 14B Instructor: Dr. Laurence...

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