Energetics, Kinetics and Equilibrium Chemistry Flashcards
(24 cards)
What is activation energy?
the minimum amount of energy needed to start a chemical reaction
Enthalpy change of combustion
the enthalpy change which occurs when one mole of the compound is burned completely under standard conditions
Enthalpy change of neutralization
the enthalpy change which occurs when an acid and alkali react together to form a mole of water under standard conditions
Enthalpy change of formation
the enthalpy change which occurs when one mole of the compound is formed under standard conditions
Enthalpy change of reaction
the enthalpy change which occurs when equation quantities of materials react under standard conditions
Effect of increasing or decreasing temperature on equilibrium
If temperature has increased, the equilibrium will shift in the direction of the endothermic reaction, as this will absorb the added heat and counteract the temperature increase.
If temperature has decreased, the equilibrium will shift in the direction of the exothermic reaction, as this will release heat and counteract the temperature decrease.
What is bond enthalpy?
the energy required to break one mole of the bonds in a substance in the gaseous state
What is the mean bond enthalpy?
the mean value of the bond enthalpy values for the X-Y bond averaged across a wide range of compounds
What is Hess’s Law?
The total enthalpy change in a chemical reaction is independent of the route by which the chemical reaction takes place as long as the initial and final conditions are the same
What is Dynamic Equilibrium?
When both the rates of the forward and backward reactions are equal to each other and the concentrations of reactants and products remain constant
Effect of increasing or decreasing temperature on equilibrium
Increasing temperature will shift reaction to the endothermic direction. Decreasing temperature will shift equilibrium to the exothermic direction
Effect of increasing or decreasing pressure on equilibrium
Increasing pressure favors the side with fewer moles of gas so the equilibrium will shift to the side with less moles and the yield of less products will increase. Decreasing pressure favors the side with more moles so equilibrium will shift to the side of the reaction with more moles and its product yield will increase
Effect of increasing or decreasing concentration on equilibrium
Increasing concentration of a reactant or product moves the equilibrium position to the other side. Decreasing concentration of a product or reactant moves the equilibrium position to the same side
Effect of increasing temperature on collision theory of reaction
It will allow particles to collide with an energy greater than the activation energy due to them having a higher kinetic energy. The number of successful collisions increases so the rate of reaction increases
Effect of increasing pressure of gases on collision theory of reaction
Effect of increasing pressure of gases means that the same number of gas particles but in a smaller volume. So there is a high probability of particles to collide more frequently and successfully.
Effect of increasing surface area on collision theory of reaction
Effect of increasing surface area of solids means that there is a greater number of particles exposed so there are more collisions
Homogenous mixture
All components of the reaction are in the same phase
Heterogenous mixture
All the components of the reaction are not in the same phase
What is equilibrium constant?
Tells the position of equilibrium constant if the Kc is less than 1 then the position of equilibrium is towards the reactants.
If Kc is more than 1 then the position of equilibrium is the towards the products
Homogenous catalyst
Catalysts that are in the same phase or state to the species in the reaction
Heterogenous catalyst
Catalysts that are in a different phase or state to the species in the reaction.
Adsorption
A solid catalyst works by adsorbing molecules onto the active site on the surface of the catalyst. These sites increase the proximity of molecules and weaken the covalent bonds in the molecules so that reactions occur more easily and the rate is increased
What factors affect the equilibrium constant Kc?
The equilibrium constant Kc is a value that depends solely on temperature. Changes in concentration, pressure, or the addition of a catalyst will not alter the value of the equilibrium constant; they will only affect the position of the equilibrium.
What factors affect the equilibrium constant Kp
