CHEM 1061 1st Edition Lecture 13 Outline of Last Lecture I Molar Mass of a Gas II Partial Pressure of a Gas III Collecting Gases Over Water Outline of Current Lecture IV Stoichiometry with Gas Laws V Diffusion and Effusion VI Thermochemistry VII Heat and Work VIII First Law of Thermodynamics Current Lecture Stoichiometry with Gas Laws Use the gas law quanitites mol Ex 2NaN3 s 2 Na s 3N2 g V 75 0 L T 300 K P 1 atm R 0 0821 How many grams of NaN3 are needed PV nRT n PV RT 132 g Diffusion and Effusion These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Diffusion movement of gas through another gas Effusion movement of gas through a vacuum The rate of effusion inversely proportional to the square root of molar mass Compare two gases Rate A Rate B OR Square root of Molar Mass B Square root of molar mass A Real Gases Used in extreme conditions of low T and high P Deviates from Ideal Gas Las with Vander Waals Equation Correction Factors Table 5 4 Thermochemistry Thermochemistry is heat in chemical and physical change Potential energy energy due to position Kinetic energy energy due to motion system part of the universe that we re focusing on Surroundings everything else that is not in the system internal energy E Change in E E final E initial Change in E transfer of E between system and surroundings Chemical change change in E E products E reactants E final E initial change in E 0 Energy is released to surroundings from system E final E initial change in E 0 Energy is absorbed from surroundings from the system Heat and Work Heat q energy transferred as a result of difference in temperature between system and surroundings Work w energy transferred when an object is moved by a force Change in E q w Energy transferred into system Energy transferred out of system If only heat w 0 change in E q w q 0 q heat released q negative change in E is negative heat absorbed q positive change in E is positive If only work q 0 Change in E q w 0 w w work done by a system final energy is less w negative change in e is negative work done on a system final energy more w positive change in e is positive If both are present you must look at the magnitude to determine E First Law of Thermodynamics Energy conservation energy is neither created nor destroyed Change in E universe change in E system change in E surroundings 0
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