Announcements Pre & Post-lecture Assignments (Lon- Capa) 8:00 am Tuesday & Thursday Lab write-up 1 due Friday in discussion Textbook homework Assignment 3 due Friday in discussion (pg. 16) Electronic Homework #3 due next Wednesday at 10:00 pm
Clicker #1 Will a drinking straw work on the moon? Assume that it is in a glass of water (and the water is staying in the glass). Yes, it will work the same way. Yes, but it will not work as well due to less gravity. Yes, but it will not work as well because there is no air. No, it will not work because there is less gravity. No, it will not work because there is no atmospheric pressure.
The Straw 1. Define 2. Explain (use Kinetic Molecular Theory) The system Constant variables Changing variables 2. Explain (use Kinetic Molecular Theory) 3. Draw/Diagram
Clicker #1: Write & Discuss When a balloon is placed in a vacuum chamber, what will happen to the balloon after the vacuum pump is turned on? Pop Expand Stay the same size Shrink Completely deflate Write an explanation in your notes describing why you made your choice using principles of kinetic molecular theory.
Equations and Units (Use carefully!) PV = nRT (where R = 0.08206 L·atm/mol·K, the universal gas constant)
Problem #1 A 10.0 L sample of 0.45 moles of gas is present at 780 torr. What is the temperature of the gas in degrees Celsius? Size of…? 1) 2) 3) 1 2 3
Problem #1 A 10.0 L sample of 0.45 moles of gas is present at 780 torr. What is the temperature of the gas in degrees Celsius?
Clicker #2 0°C to 40°C is double the temperature of 0°C to 20°C. Does this mean you have twice the amount of kinetic energy in your system? A) Yes. If the temperature doubles then the kinetic energy must also double. They are directly related. B) No. Temperature is related to the heat energy of the gas particles, not the kinetic energy of the gas particles. C) No. Temperature is related to the kinetic energy of the gas particles but must be in relationship to the Kelvin scale.
Problem #2 The vacuum chamber initially contains 2.0 moles of nitrogen gas at a pressure of 1.0 atm. If gas is removed until the new pressure in the container is 0.75 atm, how many moles of gas left the container?
Problem #3 Placing the hot pack into the vacuum chamber increased the temperature from 21C to 23C. If the pressure was initially 1.00 atm, what is the new pressure? (Assume the chamber remained closed and no gas was added or escaped.)
Clicker #3
Problem #4 As a result of his experiences in the vacuum chamber, the marshmallow man has increased in size and is now 120. mL, facing a reduced pressure of 0.80 atm. When the chamber is allowed to return to an external pressure of 1.0 atm, what will the final size of Mr. Mallow be?
Clicker #4 The temperature of an ideal gas in a flexible container is reduced from 50°C to 25°C. How does the initial volume of the container (V1) compare to the final volume of the container (V2)? V1 and V2 are the equal V1 is twice V2 V2 is twice V1 V1 greater than V2 but less than twice as great V2 is greater than V1 but less than twice as great