Thermodynamics Flashcards

1st law of thermodynamics the total energy of the universe is constant 2nd law of thermodynamics the total entropy of the universe is always incresing 3rd law of thermodynamics the entropy of every pure perfectly formed crystalline substance at absolute zero is zero a negative delta H is what kind of reaction? exothermic a positive delta H is what kind of reaction? endothermic definition of entropy measure of disorder 4 rules of entropy 1. gases have greater entropy than liquids 2. liquids have greater entropy than solids 3. entropy of a system increases as temp increases 4. in a chemical reaction the side with more mols has greater entropy thermochemistry the heat changes that occur during chemical reactions energy the capacity for doing work or supplying heat what is the energy stored in chemical bonds called? chemical potential energy heat energy that transfers from one object to another becuase of a temperature difference between them. calorie the quantity of heat needed to raise the temp of 1g of pure water 1 degree C kilocalorie equal to 1000 calories joule the SI unit of heat and energy named after the English physicist James Prescott Joule how many joules in 1 calorie? 4.184 Joules Heat capacity the amount of heat needed to increase the temp of an object exactly 1 degree C Specific heat capacity the amount of heat it takes to raise the temp of 1g of the substance 1 degree C calorimeter a device for measuring heat changes enthalpy the heat content of a system at constant pressure what does delta H stand for? heat of reaction or enthaply of reaction Hess's law if you add two or more thermochemical equations to get the final equation, then you can also add the heat of reaction to five the final heat reaction. standard heat of formation the change in enthaply that accompanies the formation of one mol of a compound from its elements with all substances in their standard states at 25 degrees C free energy energy that is available to do work spontaneous reactions reactions that occur naturally and that facor the formation of products at the specified conditions nonspontaneous reactions reactions that do not facor the formation of products at the specified conditions standard entropy the entropy of a substance in its stable state at 25 degrees C Gibb's free energy the maximum amount of energy that can be coupled to another provess to do useful work CaCO3(s) + 176kJ ----> CaO(s) + CO2(g) a. caculate the energy required to decompose 5.20 mol of CaCO3 b. how many kcal are required? a. 915 kJ b. 219 kcal SO3 + H2O -----> H2SO4 + 129.6 kJ how much heat in kJ and kcal is released when 583 grams of SO3 reacts with water? a. 2CO2 + 43.9 kJ ----> 2CO + O2 how many molecules of CO2 can be decomposed by the addition of 22.2 kJ of heat? 6.09x10^23 molecules 2C2H6(g) + 7O2(g) ---> 4CO2(g) + 6H2O(l) calculate delta H, delta S, and delta G a. H= -3119.6 kJ/mol b. S= -620.7 J/kmol c. G= -2934.57 kJ/mol 2NO2(g) ---> N2O4(g) calculate delta H,S and G 2Fe + 3CO2 + 26.3kJ ---> Fe2O3 + 3CO a. calculate kJ for 7.3 mols of Fe b. is this a positive or negative enthalpy change? a. 96 kJ b. positive 2Mg + O2 ----> 2MgO + 288kcal a. calculate kcal for 0.12 mols of Mg b. calculate kJ a. -17kcal b. -71kJ C2H4 + 3O2 ----> 2CO2 + 2H2O + 1.39x10^3 calculate the heat for 1.87g of C2H4 -92.7kJ I2(s) ----> I2(g) calculate delta H,S and G H=62.438 kJ/mol S=144.56 J/kmol G=19.327 kJ/mol 3CO(g) + Fe2O3(s) ----> 2Fe(s) + 3CO2(g) calculate delta H,S and G H= -24.7 kJ/mol S= 16.36 J/kmol G= -29.4 kJ/mol 2NO2(g) ---> 2NO(g) + 2H2O(g) calculate delta H,S and G H= -369.5 kJ/mol S= 319.05 J/kmol 2NO(g) + O2(g) ----> 2NO2(g) calculate delta H,S and G H= -144.1 kJ/mol S= -146.54 J/kmol 2HF(g) ---> H2(g) + F2(g) at 1030. C calculate delta H,S and G H= 542.2 kJ/mol S= -14.10 J/kmol G= 560.6 kJ/mol NaOH(s) + HCl(aq) ---> NaCl(aq) + H2O(l) at 85.0 C calculate delta H,S and G H= 100.33 kJ/mol S= 64.4 J/kmol G= -123.4 kJ/mol