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Chemical equilibrium and kinetics
Module: General and Organic Chemistry (AOC106DI)
26 Documents
Students shared 26 documents in this course
University: Coventry University
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Catalysis:
A catalyst is a chemical that speeds up a reaction without being consumed in the process.
The activation energy of most catalysts is reduced. With the activation energy reduced,
more collisions will have enough relative kinetic energy to cause a reaction. As a result,
more reactions will occur, and the overall reaction rate will increase. Because a catalyst
boosts both forward and reverse processes, it does not change the equilibrium constant.
Heterogeneous catalysts are catalysts that are in a different phase than the reactants or
products. The reactants and products are usually gases or liquids, while the catalysts are
usually solids. In the same phase as the reactants and products is a homogeneous catalyst.
These catalysts are frequently liquid or gaseous in nature. Homogeneous catalysts are
usually aqueous acids and bases.
Equilibrium:
Many chemical reactions are reversible, and forward and reverse reactions can happen
simultaneously. Chemical equilibrium occurs when the rate of the forward reaction is
equal to the rate of the backward reaction.
A constant K characterises the state of equilibrium:
aA + bB cC + dD ←→
where a, b, c, and d are the corresponding stoichiometric coefficients.
K = [C]c [D]d / [A]a [B]b
The reaction quotient:
For reactions that are not in equilibrium, the following equation is used:
Q stands for reaction quotient, which is used to anticipate which way a reaction would go.
Q will constantly fluctuate toward K because reactions always progress toward
equilibrium. For a reaction, Q and K can be compared to determine which direction the
reaction will go.
1. The reaction is at equilibrium if Q equals K.
2. When Q exceeds K, the ratio of products to reactants is larger than when the system is at
equilibrium. This indicates that the reverse reaction rate will be higher than the forward
rate.