140 likes | 422 Vues
AP Chemistry Unit 5 – States of Matter. Lesson 4 – Kinetic/Molecular Theory Book Section: 10.7. Kinetic-Molecular Theory. This is a model that aids in our understanding of what happens to gas particles as environmental conditions change. This determines what is an ideal gas .
E N D
AP ChemistryUnit 5 – States of Matter Lesson 4 – Kinetic/Molecular Theory Book Section: 10.7
Kinetic-Molecular Theory • This is a model that aids in our understanding of what happens to gas particles as environmental conditions change. • This determines what is an ideal gas.
Main Tenets of Kinetic-Molecular Theory • The combined volume of all molecules of the gas is negligible relative to the total volume in which the gas is contained. • In other words, the volume of the gas molecules themselves doesn’t matter.
Main Tenets of Kinetic-Molecular Theory • Attractive and repulsive forces between gas molecules are negligible.
Main Tenets of Kinetic-Molecular Theory • Energy can be transferred between molecules during collisions, but the average kinetic energy of the molecules does not change with time, as long as the temperature of the gas remains constant.
Main Tenets of Kinetic-Molecular Theory • The average kinetic energy of the molecules is proportional to the absolute temperature.
1994 MC #45 • A sample of an ideal gas is cooled from 50.0 ºC to 25.0 ºC in a sealed container of constant volume. Which of the following values for the gas will decrease? • The average molecular mass of the gas • The average distance between the molecules • The average speed of the molecules • I only B) II only C) III only D) I and III E) II and III
1994 MC #45 • A sample of an ideal gas is cooled from 50.0 ºC to 25.0 ºC in a sealed container of constant volume. Which of the following values for the gas will decrease? • The average molecular mass of the gas • The average distance between the molecules • The average speed of the molecules • I only B) II only C) III only – 44% correct, medium D) I and III E) II and III
1999 MC #22 • A hot air balloon, shown above, rises. Which of the following is the best explanation for this observation? • The pressure on the inside of the walls of the balloon increases with increasing temperature. • The difference in temperature between the air inside and outside the balloon produces convection currents. • The cooler air outside the balloon pushes in on the walls of the balloon. • The rate of diffusion of cooler air is less than that of warmer air. • The air density inside the balloon is less than that of the surrounding air.
1999 MC #23 • A hot air balloon, shown above, rises. Which of the following is the best explanation for this observation? • The pressure on the inside of the walls of the balloon increases with increasing temperature. • The difference in temperature between the air inside and outside the balloon produces convection currents. • The cooler air outside the balloon pushes in on the walls of the balloon. • The rate of diffusion of cooler air is less than that of warmer air. • The air density inside the balloon is less than that of the surrounding air. – 68% correct, easy
1999 MC #44 • A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature? • The volume of the gas increases. • The pressure of the gas decreases. • The average speed of the gas molecules remains the same. • The total number of gas molecules remains the same. • The average distance between the gas molecules increases.
1999 MC #44 • A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature? • The volume of the gas increases. • The pressure of the gas decreases. • The average speed of the gas molecules remains the same. – 54% correct, medium • The total number of gas molecules remains the same. • The average distance between the gas molecules increases.
Homework: 10.72, 10.74 • Next week: • Monday: Volume-Temperature Behavior of Gases Lab • Tuesday: Graham’s Law of Effusion (10.8) • Wednesday: Volume-Temperature Behavior of Gases Lab • Thursday: Van der Waals Equation (10.9) • Friday: Gas Stoichiometry (10.5) • Due Dates: • Volume-Temperature Behavior of Gases: 11/30 • States of Matter Exam: Monday, 12/6 • Molar Mass of Condensable Vapor: 12/8 • Problem Set 4: 12/10