exam 3 - Version 167 – Exam 3 – mccord – (50970) 1...

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 167 – Exam 3 – mccord – (50970) 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. McCord CH301 This exam is only for Dr. McCord’s CH301 classes. 001 10.0 points In which of these compounds would you find ONLY dispersion forces existing between the molecules? I. HBr; II. CH 2 Cl 2 ; III. CCl 4 ; IV. CO 2 . 1. IV only 2. III only 3. I and IV only 4. III and IV only correct 5. II only 6. I and III only 7. I and II only 8. I only 9. II and IV only 10. II and III only Explanation: A nonpolar covalent molecule would have only dispersion forces with another nonpolar covalent molecule. 002 10.0 points Sulfur dioxide reacts with oxygen gas to pro- duce sulfur trioxide. What volume of oxygen gas will react with 15.0 L of sulfur dioxide if both gases are at 101.3 kPa and 125 ◦ C? 1. 30.0 L 2. 3.75 L 3. 5.00 L 4. 15.0 L 5. 7.50 L correct Explanation: The balanced equation is 2 SO 2 + O 2 → 2 SO 3 003 10.0 points Which of the following can form intermolecu- lar hydrogen bonds? 1. H 2 CO 2. PH 3 3. CH 3 COCH 3 4. (CH 3 ) 2 NH correct Explanation: Only molecules with H attached to the electronegative atoms N, O, and F can hy- drogen bond. Of the molecules given only (CH 3 ) 2 NH 2 has the H directly bonded to N, so it can undergo hydrogen bonding. 004 10.0 points As we increase the temperature of a liquid, its properties change. Which of the following would NOT be an expected change in the properties of a typical liquid as we increase its temperature? 1. increase in vapor pressure 2. increase in surface tension correct 3. decrease in viscosity 4. decrease in density Version 167 – Exam 3 – mccord – (50970) 2 5. increase in tendency to evaporate Explanation: As temperature increases, molecules have more energy to overcome intermolecular forces/bonds. Therefore viscosity, surface tension and density will decrease and vapor pressure and rate of evaporation will increase. 005 10.0 points What is the root mean square speed of carbon dioxide molecules at 98 ◦ C? 1. 45.6 m · s − 1 2. 153 m · s − 1 3. 459 m · s − 1 correct 4. 574 m · s − 1 5. 236 m · s − 1 Explanation: T = 98 ◦ C + 273 . 15 = 371 . 15 K MW = 44 . 0095 g / mol = 0 . 0440095 kg / mol R = 8 . 314 N K · mol The root mean square speed is v = radicalbigg 3 R T MW = radicalBigg 3 ( 8 . 314 N K · mol ) (371 . 15 K) . 0440095 kg / mol = 458 . 635 m / s . 006 10.0 points A 750.0 mL metal bulb is filled with 0.421 g of CH 4 and an unknown mass of NH 3 . If the total pressure in the bulb is 3.77 atm at 315 ◦ C, then how much NH 3 is also in the bulb? 1. 0.00713 grams 2. 0.549 grams correct 3. 0.996 grams 4. 1.17 grams 5. 0.0323 grams 6. 2.39 grams 7. 14.5 grams Explanation: n CH 4 = (0 . 421 g) · mol 16 g = 0 . 0263 mol V = 750 mL = 0 . 75 L T = 315 ◦ C + 273 = 588 K Applying the ideal gas law equation, P V = n RT n tot = P V RT = (3 . 77 atm) (0 . 75 L) (0 . 08206 L ·...
View Full Document

This note was uploaded on 11/18/2010 for the course CHEM 301 taught by Professor Wandelt during the Fall '08 term at University of Texas at Austin.

Page1 / 9

exam 3 - Version 167 – Exam 3 – mccord – (50970) 1...

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