 The force exerted per unit area  As the number and/or the speed of the collisions increases, the rate of change of the momentum of the particles must increase. Therefore, a greater force is needed.  Pressure increases with the number and rate at which molecules collide with the walls of the container (not with each other)

 Boyle’s Law  At a constant temperature, pressure is inversely proportional to the volume

 Charles’ Law  At a constant pressure, the temperature is directly proportional to the volume Molecules at a higher temperature have a higher avg. KE, which means they will collide with the walls of the container more often. In order to keep the pressure constant, the volume must increase to keep the rate of the collisions constant.

 Gay-Lussac’s Law  At a constant volume, the pressure is directly proportional to the temperature Molecules at a higher temperature have a higher avg. KE, which means they will collide with the walls of the container more often, therefore increasing the pressure.

 It’s convenient to express the amount of gas in a given volume in terms of the number of moles, n  One mole is the amount of the substance that contains as many particles as there are atoms in 12 g of carbon-12

 The number of particles in a mole is called Avogadro’s Number  N A =6.02 x particles / mole  The mass of an individual atom can be calculated:

 Equal volumes of gas at the same temperature and pressure contain the same numbers of molecules  Corollary: At standard temperature and pressure, one mole quantities of all gases contain the same number of molecules  This number is N A  Can also look at the total number of particles: N = n N A

 Collection of atoms or molecules that move randomly.  All molecules are identical and spherically shaped  Exert no long-range force on one another  Collisions between molecules are elastic, therefore molecules move at constant velocity between collisions  The molecules occupy a negligible fraction of the volume of the container  Gases at high temperatures and lower pressures behave approximately as an ideal gas

 Summarizes Boyle’s Law, Charles’ Law, and Guy-Lussac’s Law  PV = n R T  R is the Universal Gas Constant  R = 8.31 J / mole K  Since PV / T = nR (which is a constant for a gas in a closed container) we can write the following relationship:

 The temperature of a gas In Kelvin is directly proportional to average Kinetic Energy (E k ) of a molecule  E k = 3/2 k B T k B = Boltzmann’s constant 1.38 x J K -1 T = temperature (in K) Since k B is defined as R/ N A, the equation can be written as E k = 3 R T 2 N A

 Isobaric  Pressure stays constant, while the volume and temperature of a gas change

 Isochoric (Isovolumetric)  Volume stays constant, while the pressure and temperature of a gas change

 Isothermal  Temperature stays the same, while the pressure and volume of a gas changes  Because the substance isn’t changing phase and its temperature is remaining constant,  U = 0

 Adiabatic  No heat is exchanged with the surroundings (because the process happens so quickly)  Q = 0  Pressure, volume and temperature do change   U = -W

 Isochoric  Isobaric  Isothermal  Adiabatic

Whenever thermal energy is added to a gas, it transforms to internal energy and/or work Thermal energy can do work, which is the concept behind the internal combustion engine This is basically Conservation of Energy

An object or system will naturally proceed from a state of order to disorder (will break down, become unorganized). Disorder is also known as ENTROPY The entropy of the Universe increases in all natural processes

To make a system more ordered, energy or work must be inputted into the system. Increased Entropy Decreased Entropy Work done to order system

Entropy and Phases of Matter: Increasing Entropy Decreasing Entropy SolidLiquidGas Decreasing Temperature Increasing Temperature

 A perpetual motion machine would operate continuously without input of energy and without any net increase in entropy  Perpetual motion machines of the first type would violate the First Law, giving out more energy than was put into the machine  Perpetual motion machines of the second type would violate the Second Law, possibly by no exhaust  Perpetual motion machines will never be invented

 If form A can be completely converted to form B, but the reverse is never complete, A is a higher grade of energy than B  When a high-grade energy is converted to internal energy, it can never be fully recovered as high-grade energy  Degradation of energy is the conversion of high- grade energy to internal energy  In all real processes, the energy available for doing work decreases  Example- combustion of gasoline

 The entropy of the Universe always increases  The entropy of the Universe should ultimately reach a maximum  At this time, the Universe will be at a state of uniform temperature and density  This state of perfect disorder implies no energy will be available for doing work  This state is called the heat death of the Universe

It is impossible to reach the temperature of absolute zero (0 K)  Thermal energy doesn’t flow from a lower temperature to a higher temperature.  It is impossible to have a 100% efficient heat pump

 “The Law that Entropy increases,- the Second Law of Thermodynamics- holds, I think, the supreme position among the laws of Nature…. ….if your theory is found to be against the Second Law of Thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.” Arthur S. Eddington, The Nature of the Physical World (1930), p. 74.

Does the apparent order of life on Earth imply the 2 nd law is wrong or that some supernatural being is directing things? No. The second law applies to closed systems, those with no energy coming in or going out. As long as the Sun shines more energy falls on the Earth, and more work can be done by the plants to build new mass, release oxygen, grow, metabolize.

 “‘Organized’ systems are to be carefully distinguished from ‘ordered’ systems. Neither kind of system is ‘random,’ but whereas ordered systems are generated according to simple algorithms and therefore lack complexity, organized systems must be assembled element by element according to an external ‘wiring diagram’ with a high information content... Organization, then, is functional complexity and carries information. It is non-random by design or by selection, rather than by the a priori necessity of crystallographic ‘order.’”  [Jeffrey S. Wicken, The Generation of Complexity in Evolution: A Thermodynamic and Information-Theoretical Discussion, Journal of Theoretical Biology, Vol. 77 (April 1979), p. 349]

 The apparent increase in organized complexity (i.e., decrease in entropy) found in biological systems requires two additional factors besides an open system and an available energy supply. These are: 1. a “program” (information) to direct the growth in organized complexity (DNA) 2. a mechanism for storing and converting the incoming energy. (photsynthesis, metabolism)

Information indicates an intelligent source or designer