> Energy : Chemical Equilibrium Quiz
Energy : Chemical Equilibrium Quiz
Most chemical reactions don’t go to completion. Often, they reach a point of balance or stabilization. Sometimes reactions are reversible, meaning that they can occur in both the forward and backward directions. An example of a reversible reaction is the synthesis of ammonia from hydrogen and nitrogen.
Forward: N2 + 3H2 --> 2NH3
Backward: N2 + 3H2 <-- 2NH3
The equation is typically combined like so:
N2 + 3H2 <----> 2NH3
Equilibrium means that opposing processes are in balance. Reversible reactions balance each other because they take place at equal rates. This is called chemical equilibrium. Be mindful that equilibrium is a state of action; movement is constant. This leads to the law of chemical equilibrium, which states that at a given temperature, a chemical system may reach a state in which a particular ratio of reactant and product concentrations has a constant value.
General form of an equilibrium reaction:
aA + bB <----> cC + dD
“A & B” are reactants, “C & D” are products, and “a, b, c, d” are coefficients. To determine the equilibrium constant (K) from the general model:
K = [C]^c [D]^d / [A]^a [B]^b
If a K-value greater than 1 is obtained, more products than reactants at equilibrium. If a K-value less than one is obtained, there are more reactants than products at equilibrium.
Homogeneous equilibrium is when all reactants and products are in the same phase or state at equilibrium. Heterogeneous equilibrium is when reactants and products are present in more than one phase or state.
Le Chatelier’s principle was developed as a way to control equilibrium to make chemical reactions more productive. Le Chatelier’s principle states that if a stress is applied to a system (reaction), then the system shifts in that direction. A stress is any kind of change in a system at equilibrium that upsets the equilibrium. Stressors that affect chemical equilibrium: concentration, temperature and volume.
For the following quiz, review the above summary to assist you in answering the question. Select the best choice from the given answers.
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