chemical equillibria Flashcards
(27 cards)
What symbol is used to represent reversible reactions?
Double arrow
Indicates that reactants can form products and vice versa.
What occurs at equilibrium in a reversible reaction?
The forward and reverse reactions proceed at equal rates and the concentrations of reactants and products remain constant.
Define dynamic equilibrium.
The point when the forward and backward reactions happen at the same rate, with constant concentrations of reactants and products in a closed system.
What is a closed system?
A system in which none of the reactants or products escape from the reaction mixture.
What is an open system?
A system where matter and energy can be lost to the surroundings.
Define a homogeneous system.
A system where all the chemicals are in the same place.
What does Le Chatelier’s Principle state?
If a system at equilibrium is disturbed, the position of equilibrium will shift in the direction that counteracts the effect of the change.
What happens to equilibrium when temperature increases?
Equilibrium shifts to favor the endothermic reaction.
What happens to equilibrium when temperature decreases?
Equilibrium shifts to favor the exothermic reaction.
What is the effect of increasing the concentration of reactants on equilibrium?
Equilibrium shifts to favor the production of products, moving to the right.
What happens when the concentration of reactants decreases?
Equilibrium shifts to favor the production of reactants, moving to the left.
What is the effect of increasing pressure on equilibrium?
Equilibrium shifts to favor the side with fewer moles.
What occurs when pressure decreases in a reaction at equilibrium?
Equilibrium shifts to favor the side with more moles.
What compromise is often made in industrial reactions regarding temperature?
A temperature that is high enough for a fast rate but low enough to give a good yield of the desired product.
What is the equilibrium constant Kc?
A value that expresses the relationship between the concentration of reactants and products at equilibrium in a reversible reaction.
What does a large Kc (greater than 1) indicate?
Equilibrium lies to the right, as product concentration is greater than reactant concentration.
What does a small Kc (less than 1) indicate?
Equilibrium lies to the left, as reactant concentration is greater than product concentration.
Write the expression for Kc.
Kc = [C]^c x [D]^d / [A]^a x [B]^b
What does the ‘I’ in ICE table stand for?
Initial moles.
What does the ‘C’ in ICE table stand for?
Change in moles.
What does the ‘E’ in ICE table stand for?
Equilibrium moles.
How do you calculate equilibrium concentrations from moles?
Equilibrium moles = concentration / volume.
What happens to Kc when the temperature increases for an exothermic reaction?
Kc decreases as equilibrium shifts to the left, favoring reactants.
What happens to Kc when the temperature decreases for an exothermic reaction?
Kc increases as equilibrium shifts to the right, favoring products.
