Equilibrium: Heat energy

Extract

[...] Ammonia is formed at 2x the rate at which nitrogen is consumed. Static Equilibrium Static equilibrium does not occur in a chemical system: The reaction has stopped-no reaction is taking place. All product molecules will remain product. All unused reactant molecules will remain unreacted. Dynamic Equilibrium At some point in time, the concentrations of the reactants and products stop changing and they are in a dynamic equilibrium with each other Reactions continue to take place even if you don't see it. [...]

[...] When you have to reverse a reaction before adding them, you have to use the reciprocal of the equilibrium constant. K values are customarily written without units. Equilibrium expression involving pressure When a reaction involves gases, it is possible to express the equilibrium constant in terms of partial pressure of the gases present or in terms of molar concentration Derivation of Equilibrium Gas Laws-molar concentration of an ideal gas is directly proportional to its partial pressure, so: PiV therefore (ni/V)RT n/V is the molar concentration of the gas, represented by which is the molar concentration of the inert gas P =CRT Relationship between Kc and Kp are derived from ideal gas law Kp = Kc(RT)Δn Kp = partial pressure constant (atmospheres as units) Kc = molar concentration constant (molarities as units) R = ideal gas constant l-atm/mol-K T = absolute temperature Δn = moles of product gas moles of reactant gas + - + the difference in the sums of the coefficients for the gaseous products and reactants Put values for partial pressures into the equilibrium law and solve for then compare it to K In homogeneous reactions where the number of moles of reactants and products are equal, Kc = Kp If comparing all the systems, no value of Q equals the known Kp, then none of the systems are in equilibrium Application of equilibrium constant The value of Keq indicates extent to which reactants are converted into products in a chemical reaction If large-indicates amount of products present at equilibrium is much greater than amount of reactants A very large Keq (>1010) indicates that the reaction goes to completion Equilibrium position is far to the right Generally have a large, negative ΔE A very small Keq indicates very little product formed and virtually no visible reaction occurs Equilibrium position is far to the left If K = the equilibrium mixture contains approximately equal amounts of reactants and products Reaction Quotient Defined as the number obtained by entering all the required concentrations into the equilibrium law and calculating the result. [...]

[...] B/C come into play because nature tries to achieve minimum energy and maximum disorder NO2 { N2O4 At room temperature, it is impossible to have pure NO2 or N2O4. However, in a sealed tube (closed system), the ratio is a constant: This phenomenon is known as chemical equilibrium. Haber Process The Haber Process-synthesis of ammonia from elemental nitrogen and hydrogen (produce fertilizer, explosives) N2(g) + 3H2(g) 2NH3(g) Catalyst needed to speed up forward/reverse reactions because: N2 molecule has very strong triple bond-very unreactive. [...]

[...] This is done by decreasing the total number of gaseous molecules in the system Decreasing volume will always shift reaction in the direction that produces fewer more moles of gas-to the side where there are fewer gas molecules N2(g) + 3H2 2NH3(g) shifts to the right to decrease the total molecules of gas present When the container volume is increased, the system will shift so as to increase its volume Increasing volume shifts to the side that will lead to the production of more moles of gas-to the side where there are more gas molecules N2 + 3H2 2NH3 shifts to the left to increase the total number of molecules of gas present Change in the temperature The only experimental variable that has any effect on the value of the equilibrium constant is temperature For some reactions, the equilibrium constant increases as the temperature increases, for others it decreases Which direction it changes depends on whether the reaction is exothermic (ΔH is negative) or endothermic (ΔH is positive) Exothermic reaction gives off heat to the surroundings Reactants Products + Heat Increasing temperature favors reactants and K decreases Decreasing temperature favors products and K increases Endothermic reaction absorbs heat from the surroundings Heat + Reactants Products Increasing temperature favors products and K increases Decreasing temperature favors reactants and K decreases Addition of solvent to an equilibrium system in solution The addition of a pure solvent shifts the system in a direction that will increase the number of dissolved particles Catalysts and Equilibrium A catalyst increases the rate of a reaction by lowering its activation energy The addition of a catalyst increases the forward and reverse reactions equally A system at equilibrium-will remain at equilibrium A system not at equilibrium-addition will shorten the time needed to attain equilibrium Fireball design template Equilibrium Chemical Equilibrium Chemical equilibrium occurs (state where concentrations of all reactants and products remain constant with time): All reactions carried out in a closed vessel will reach equilibrium. [...]

[...] B/C come into play because nature tries to achieve minimum energy and maximum disorder NO2 { N2O4 At room temperature, it is impossible to have pure NO2 or N2O4. However, in a sealed tube (closed system), the ratio is a constant: This phenomenon is known as chemical equilibrium. Haber Process The Haber Process-synthesis of ammonia from elemental nitrogen and hydrogen (produce fertilizer, explosives) N2(g) + 3H2(g) 2NH3(g) Catalyst needed to speed up forward/reverse reactions because: N2 molecule has very strong triple bond-very unreactive. [...]