Answers Version A First Mid 2-1-08

Answers Version A First Mid 2-1-08 - Chemistry 1B First...

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1 Chemistry 1B First Mid-Term Exam, 2-1-08 Answer Key Version A . 1. Given the following enthalpies, what is the value of Δ H f o of C 2 H 4 ( g )? Δ H f o of CO 2 ( g ) = -393.5 kJ/mol Δ H f o of H 2 O( l ) -285.9 kJ/mol 2 C 2 H 4 ( g ) + 6 O 2 ( g ) 4 CO 2 ( g ) + 4 H 2 O ( l ) Δ H = -2822.2 kJ/mol A. -731.7 kJ/mol B. +731.7 kJ/mol C. -52.3 kJ/mol D. +52.3 kJ/mol E. -2090.5 kJ/mol 2. Both CO 2 (g) and Ne (g) are heated from 25 o C to 30 o C at constant pressure. Which of the following statements is true ? A. The amount of heat required for Ne (g) is more than it is for CO 2 (g) B. The change in internal energy for each is the same C. The change in internal energy of CO 2 (g) is more than it is for Ne (g) D. More work is done in heating CO 2 (g) than for Ne (g) E. No work is done in heating either gas 3. The value of Δ H f o of HCN (g) is 135 kJ/mol. Which of the following balanced equations represents a reaction whose enthalpy change equals 135 kJ? A. H (g) + C (g) + N (g) HCN (g) B. H (g) + C (graph) + N (g) HCN (g) C. ½ H 2 (g) + C (graph) + ½ N 2 (g) HCN (g) D. H 2 (g) + 2 C (graph) + N 2 (g) 2 HCN (g) E. None of these 4. A sample of 98.0 g of nitrous oxide gas (N 2 O) is heated from 56°C to 169°C at constant pressure of 5.00 atm. Which of the following statements about the process is true ? A. Δ H is positive B. Δ E is negative C. Work, w, is positive D. Heat, q, is negative E. No work is done in the process 5. When a liquid is vaporized at constant temperature (91°C) and pressure (1.00 atm), 39.6 kJ of heat are absorbed. Which of the following statements is true ?
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Answers Version A First Mid 2-1-08 - Chemistry 1B First...

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