# exam1 - Version 249 Exam 1 VANDEN BOUT (53585) 1 This...

This preview shows pages 1–3. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Version 249 Exam 1 VANDEN BOUT (53585) 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points For the decomposition of ammonia to nitro- gen and hydrogen, the equilibrium constant is 1 . 47 10 6 at 298 K. Calculate the temper- ature at which K = 1 . 00. For this reaction, H = 92 . 38 kJ mol 1 . 1. 193 K 2. 353 K 3. 466 K correct 4. 219 K 5. 492 K Explanation: 002 10.0 points Consider a series of chloride salts (MCl 2 ). As the charge-to-size ratio of M 2+ (decreases, increases) the hydration energy of M 2+ (de- creases, increases, does not change) in magni- tude and the crystal lattice energy of MCl 2 (decreases, increases, may increase or de- crease) in magnitude. 1. increases; does not change; may increase or decrease 2. increases; decreases; increases 3. decreases; increases; increases 4. decreases; decreases; increases 5. increases; increases; increases correct 6. increases; decreases; decreases 7. increases; increases; decreases Explanation: As charge-to-size ratio increases, hydration energy and crystal latice energy also increase. 003 10.0 points Consider the reaction 2 HgO(s) 2 Hg( ) + O 2 (g) . What is the form of the equilibrium constant K c for the reaction? 1. K c = [Hg] 2 [O 2 ] [HgO] 2 2. K c = [O 2 ] [HgO] 2 3. K c = [O 2 ] correct 4. None of the other answers is correct. 5. K c = [Hg] 2 [O 2 ] Explanation: Solids and liquids are not included in the K expression. 004 10.0 points Which of the following expressions correctly describes the relationship between [H 3 O + ] and [OH ] in any aqueous solution at 25 C? 1. [H 3 O + ][OH ] = 10 14 correct 2. [OH ] [H 3 O + ] = 10 14 3. [H 3 O + ][OH ] = 14 4. [H 3 O + ] [OH ] = 10 14 5. [H 3 O + ]- [OH ] = 14 Explanation: At 25 C, K w = [H 3 O + ][OH ] = 1 . 10 14 005 10.0 points Which of the following statements is true with respect to the autodissociation of water when sipping a glass of ice water? I. pH = pOH = 7 II. pH &lt; 7 Version 249 Exam 1 VANDEN BOUT (53585) 2 III. pH = pOH IV. pH &gt; 7 1. IV only 2. II only 3. I and III only 4. III and IV only correct Explanation: Since water autodissociates, [H + ] = [OH ]. For any given temperature, the pH of pure water is defined as neutral and pH = pOH. At 25 C neutral pH = 7. K a will be smaller than 1 10 7 at 0 C because water autodissociates less than 25 C. pH will therefore be greater than 7 at 0 C. 006 10.0 points If G rxn is positive, then the forward reaction is (spontaneous / nonspontaneous) and K is (less / greater) than one....
View Full Document

## This note was uploaded on 04/16/2008 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas at Austin.

### Page1 / 10

exam1 - Version 249 Exam 1 VANDEN BOUT (53585) 1 This...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online