exam1dvb - Version 387 – Exam 1 – VANDEN BOUT –(53585...

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

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Version 387 – 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 The pH of a solution of hydrochloric acid is 2.80. What is the molarity of the acid? 1. 4 . 2 × 10 − 3 M 2. 4 . 2 × 10 − 2 M 3. 6 . 3 × 10 − 2 M 4. 1 . 6 × 10 − 3 M correct 5. 6 . 3 × 10 − 3 M Explanation: pH = 2.80 [H + ] = 10 − pH = 10 − 2 . 80 = 1 . 6 × 10 − 3 M Since HCl is a strong acid, it is completely dissociated, so its concentration here is also 1.6 × 10 − 3 M. 002 10.0 points What is the H + ion concentration in a 0.50 mol/L solution of a weak base that has an ionization constant ( K b ) of 2.0 × 10 − 8 ? 1. 8 . × 10 − 16 mol/L 2. 1 . × 10 − 8 mol/L 3. 2 . × 10 − 10 mol/L 4. 1 . × 10 − 4 mol/L 5. 1 . × 10 − 10 mol/L correct Explanation: 003 10.0 points A typical fresh egg white will have a pH of 7.80. This corresponds to 1. [H 3 O + ] of 3 . × 10 − 8 M; [OH − ] of 3 . 3 × 10 − 7 M . 2. [H 3 O + ] of 7 . × 10 − 8 M; [OH − ] of 1 . 4 × 10 − 7 M . 3. [H 3 O + ] of 8 . × 10 − 7 M; [OH − ] of 1 . 3 × 10 − 8 M . 4. [H 3 O + ] of 8 . 5 × 10 − 7 M; [OH − ] of 5 . 5 × 10 − 7 M . 5. [H 3 O + ] of 1 . 6 × 10 − 8 M; [OH − ] of 6 . 3 × 10 − 7 M correct . Explanation: 004 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; decreases; decreases 2. increases; increases; decreases 3. increases; increases; increases correct 4. decreases; decreases; increases 5. increases; decreases; increases 6. increases; does not change; may increase or decrease 7. decreases; increases; increases Explanation: As charge-to-size ratio increases, hydration energy and crystal latice energy also increase. 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 < 7 III. pH = pOH Version 387 – Exam 1 – VANDEN BOUT – (53585) 2 IV. pH > 7 1. I and III only 2. III and IV only correct 3. II only 4. IV only 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....
View Full Document

This note was uploaded on 04/12/2008 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas.

Page1 / 10

exam1dvb - Version 387 – Exam 1 – VANDEN BOUT –(53585...

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

View Full Document Right Arrow Icon
Ask a homework question - tutors are online