Chapter 13 Chemical Equilibrium
The equilibrium constant is First, write the balanced chemical equation with an ICE table. CO(g) + 2H₂(g) ⇌ CH₃OH(g). I/mol·L⁻¹: ;. The following class reactions are examples of these types of reactions: 1. . 2SO3(g); (PSO3) 2 Kp = (PSO2) 2 (PO2) Relationship between Kp and Kc: Consider When equilibrium is established at K, the concentration of CH3OH was. Definition of equilibrium constant Kp for gas phase reactions, and how to calculate Kp from Kc.
Expression for Equilibrium Constant Consider the following equilibrium system: The mixture is heated to a certain temperature and the following reaction occurs until equilibrium is established. Calculating Equilibrium Constant for reaction: Under this condition HI decomposes to produce H2 and I2 until an equilibrium is established.FSc Chemistry Book1, CH 8, LEC 7: Relation between equilibrium constants
An analysis of the equilibrium mixture shows that 0. Calculate the equilibrium concentrations of H2, I2 and HI, and the equilibrium constant Kc for the following reaction: For example, for the following equilibrium: When equilibrium is established, the partial pressure of NO2 has decreased by 1. When the equilibrium was established, the mixture was found to contain 0.
Calculate the equilibrium constants Kc and Kp for this reaction at K? Is a reaction mixture that contains 0.
Chapter 13 Chemical Equilibrium
If not, in which direction will the net reaction occur? What will be their concentrations when equilibrium is established?
Equilibrium Exercise 3 1.
- Chapter 13 – Chemical Equilibrium
What is the equilibrium constant for the following reaction? What is the equilibrium constant for the decomposition of SO3 at K according to the following equation?
Knowing the equilibrium constant, we can predict whether or not a reaction mixture is at equilibrium, and we can predict the direction of net reaction. The value of K tells us whether a reaction favors the products or the reactants.
What does the reaction quotient tell us? Why is Equilibrium Constant Important? If the initial pressure of NO2 was 3. What is the total gas pressure at equilibrium? In which direction the equilibrium will shift in either direction depends on the reaction stoichiometry. Reactions that shift right when pressure increases and shift left when pressure decreases Consider the reaction: What is the molar concentration of N2O4 at equilibrium?
Calculate the value of Kc and Kp, respectively, at K for the reaction: Methanol or methyl alcohol is produced commercially according to the following reaction: What are the equilibrium concentrations of CO and H2? Calculate the equilibrium constants Kc and Kp, respectively, for the reaction at K? The equilibrium constant is expressed depending on how the equilibrium equation is written. For example, for the following equilibrium: For example, Eq 1: The equilibrium constant for the reaction: What is the equilibrium constant for the following decomposition of SO3 at K?
This is because the concentrations of such substances are constant, regardless of the quantity. For example, the concentration of pure water is about 56 M, regardless of its volume. Examples of equilibrium constant expressions in heterogeneous equilibria are: However, equilibrium constant does not tell us how fast equilibrium will be achieved.
Using Equilibrium Constant to Predict the Direction of Net Reaction For a reaction of known Kc value, the direction of net reaction can be predicted by calculating the reaction quotient, Qc. Reaction quotient is expressed in the same manner as Kc, except that the concentrations used are not necessarily the equilibrium concentrations.
Calculating equilibrium constant Kp using partial pressures
Calculating Equilibrium Concentrations from Initial Concentrations and Kc If the equilibrium constant Kc for a reaction and the initial concentration s of reactants are known, the concentration of each component at equilibrium can be calculated.
For example, consider the reaction: If the initial concentrations of H2 and I2 are 1. Determine whether the following mixture containing 1. If not, predict the direction of net reaction that will take place to reach equilibrium. If the initial pressure of NO2 is 0. Understanding the factors that control the equilibrium positions of a chemical reaction is very important in chemical manufacturing.
Chemists and chemical engineers in charge of production want to choose conditions that would give an optimum yield of the desired products. They would want the equilibrium to lie as far to the product side as possible.
Three important factors that influence equilibrium are: The Effect of Concentration Change Consider the reaction: Similar result is obtained if some of NH3 is removed from the mixture. By periodically adding new batches of N2 and H2 gases to the reactor and removing the product NH 3the above reaction will continuously proceed in the forward direction.
While the reverse reaction increases the number of molecules and result in an increase in the total pressure. If the reaction mixture is forced into a smaller volume, the pressure will increase. For this type of reactions, the forward reaction favors a high pressure condition. If the reaction mixture is transferred to a larger container, the total gas pressure will drop and a net reaction will proceed in the reverse direction to reach new equilibrium position.
The equilibrium will shift towards the reactants side if pressure is increased by compression of the reaction mixture.
Calculating equilibrium constant Kp using partial pressures (article) | Khan Academy
This type of reactions favor low pressure conditions. Changing the overall pressure will not affect the state of equilibrium. Any changes in pressure imposed on the system have equal effects on both sides.
Equilibrium is not influenced by a pressure change that is due to addition of gases not involved in the equilibrium system.
For example, introducing helium gas into an equilibrium mixture containing H 2, N2, and NH3, will not affect its equilibrium? The Effect of Changing Temperature on Equilibrium To realize the effect of temperature on equilibrium, we have to know whether a reaction is exothermic or endothermic.
For example, the reaction: Increasing the temperature means that heat is added to the system, and the system responses by going in the opposite direction forming the reactantswhich is the direction that absorbs heat. If the temperature is lowered heat is removeda net forward reaction will occur to produce more heat. Thus, exothermic reactions favor a low temperature condition.
The following is an endothermic reaction: This type of reactions favor a high temperature condition. Thus, endothermic reactions favor a high temperature condition, and exothermic reactions favors low temperatures. In chemical kinetics we learn that catalysts speed up reaction rates, but catalysts do not affect equilibrium.
Determine whether the following reactions favor high or low pressures? Determine whether the following reactions favors high or low temperature? The following are some of the examples. Contact Process for Sulfuric Acid The production of sulfuric acid starts with the formation of sulfur dioxide, SO2, formed: However, at low temperature the reaction is very, very slow because the reaction has a very activation energy.
The reaction is normally carried out at temperature between - oC and in the presence of catalyst.