Gas Laws Describe the Behavior of Gases PDF

Section 1.8 Gas Laws Describe the Behavior of Gases Conceptual Chemistry Fourth Edition...

Section 1.8 Gas Laws Describe the Behavior of Gases Conceptual Chemistry Fourth Edition John Suchocki © 2011 Pearson Education, Inc. Chapter 2  Physical Characteristics of Gases Physical Characteristics Typical Units Volume, V liters (L) Pressure, P atmosphere (1 atm = 1.015x105 N/m2) Temperature, T Kelvin (K) Number of atoms or mole (1 mol = 6.022x1023 molecules, n atoms or molecules)  Boyle’s Law  Pressure and volume are inversely related at constant temperature.  PV = K  As one goes up, the other goes down.  P1V1 = P2V2 Robert Boyle Chemist & Natural Philosopher Listmore, Ireland January 25, 1627 – December 30, 1690 Boyle’s Law: P1V1 = P2V2 Boyle’s Law: P1V1 = P2V2  Gas Laws Describe the Behavior of Gases Boyle’s Law: Pressure and Volume The same effect can be had by decreasing the volume. © 2011 Pearson Education, Inc. Chapter 2  Gas Laws Describe the Behavior of Gases Boyle’s Law: Pressure and Volume The same effect can be had by decreasing the volume. © 2011 Pearson Education, Inc. Chapter 2  Gas Laws Describe the Behavior of Gases Boyle’s Law: Pressure and Volume There is an indirect relationship between the pressure of a gas sample and its volume at constant temperature. Decreasing the volume results in increasing the pressure. © 2011 Pearson Education, Inc. Chapter 2  Gas Laws Describe the Behavior of Gases Charles’s Law: Volume and Temperature There is a direct relationship between the volume of a gas sample and its temperature at constant pressure. An increasing temperature results in an increasing volume. © 2011 Pearson Education, Inc. Chapter 2 Charles’ Law  Volume of a gas varies directly with the absolute temperature at constant pressure.  V = KT  V1 / T1 = V2 / T2 Jacques-Alexandre Charles Mathematician, Physicist, Inventor Beaugency, France November 12, 1746 – April 7, 1823 Charles’ Law: V1/T1 = V2/T2 Charles’ Law: V1/T1 = V2/T2  Gas Laws Describe the Behavior of Gases Charles’s Law: Volume and Temperature There is a direct relationship between the volume of a gas sample and its temperature at constant pressure. An increasing temperature results in an increasing volume. © 2011 Pearson Education, Inc. Chapter 2  Gas Laws Describe the Behavior of Gases Charles’s Law: Volume and Temperature There is a direct relationship between the volume of a gas sample and its temperature at constant pressure. An increasing temperature results in an increasing volume. © 2011 Pearson Education, Inc. Chapter 2  Gas Laws Describe the Behavior of Gases Charles’s Law: Volume and Temperature Decreasing temperature results in a decreasing volume. At what temperature would a material then have zero volume?? © 2011 Pearson Education, Inc. Chapter 2  Avogadro’s Law At constant temperature and pressure, the volume of a gas is directly related to the number of moles. V = K n V1 / n1 = V2 / n2 Amedeo Avogadro Physicist Turin, Italy August 9, 1776 – July 9, 1856 Avogadro’s Law: V1/n1=V2/n2  Gas Laws Describe the Behavior of Gases Avogadro’s Law: Volume and Number of Particles There is a direct relationship between the volume of a gas and the number of gas particles it contains at constant pressure and temperature. A greater number of particles results in a larger volume. © 2011 Pearson Education, Inc. Chapter 2  Standard Temperature and Pressure (STP)  Refers to a Temperature of 0oC , and a pressure of 1atm. Keep in mind the STP values in other units: Standard Temp = 0oC or 273 Kelvin Standard Pressure = 1atm = 760 mmHg = 760 torr = 101325 Pa  Gas Laws Describe the Behavior of Gases Ideal Gas Law A gas law that summarizes the pressure, volume, temperature, and number of particles of a gas within a single equation, often expressed as PV = nRT where P is pressure, V is volume, n is number of molecules, R is the gas constant, and T is temperature. R = 0.082057 L atm/K mol © 2011 Pearson Education, Inc. Chapter 2  Kinetic Molecular Theory 1. A gas consists of tiny particles, either atoms or molecules or both. © 2011 Pearson Education, Inc. Chapter 2  Kinetic Molecular Theory 2. Gas particles are in constant random motion, colliding among themselves and with the walls of their container. © 2011 Pearson Education, Inc. Chapter 2  Kinetic Molecular Theory 3. The impacts of gas particles on the walls of the container produce a jittery force that appears as a steady push against the inner surface. This pushing force provides the pressure of the enclosed gas. © 2011 Pearson Education, Inc. Chapter 2  Kinetic Molecular Theory 4. Deviations from gas laws arise primarily because of the interactions occurring among gas particles and because gas particles are not infinitely small. © 2011 Pearson Education, Inc. Chapter 2  Kinetic Molecular Theory 5. The average kinetic energy (energy due to motion) of the gas particles is directly proportional to the temperature of the gas. © 2011 Pearson Education, Inc. Chapter 2