Thus, one way to determine whether the reactants or products are favored in an equilibrium is to compare the stabilities of two negative charges on opposite sides of the equilibrium-arrows.
Whichever side has the more stable negative charge is favored because this side is lower in energy. One way to think about why this statement is true is to consider what happens once you get to the more stable negative charge. In other words: once you get there, you stay there! Namely, Orgo 1 says you can use sodium amide NaNH 2 to deprotonate terminal alkynes. I know, I know: too many words.
What you should notice is that the equilibrium favors the negative charge on the carbon instead of the nitrogen. A second way to evaluate an equilibrium is to consider that the transfer of a proton from good bronsted acids to good bronsted bases is always favorable.
Once you understand the Protocol and the great favorability of proton-transfer, determining the equilibrium position of reactions is straightforward. By Andrew S. Applying the Protocol We all know that nature hates energy—the lower the energy, the better.
We simplify and write this constant as K eq :. Keep in mind that the only species that should be included in the K eq expression are reactants and products that exist as gases or are in aqueous solution. Reactants and products in the solid and liquid phases, even if they are involved in the reaction, are not included in the K eq expression, as these species have activities of 1.
The activity for solids and liquids is 1, so they essentially have a constant concentration of 1, and thereby have no effect on the K eq expression. As such, they are omitted. Note that because it is a solid, the activity of C s is 1, and it is omitted from the final K expression.
When looking at the K eq expression, we should notice that it is essentially a ratio relating the concentrations of products to the concentrations of reactants at equilibrium. If we know the value of K eq , we can draw some conclusions about the thermodynamics of the forward and reverse reactions. These conclusions are summarized as follows:. Privacy Policy. Skip to main content.
Chemical Equilibrium. Search for:. Equilibrium Equilibrium Chemical equilibrium is the state in which the forward reaction rate and the reverse reaction rate are equal. Learning Objectives Recall the relationship between the forward and reverse reaction rates when a reaction is at equilibrium.
Key Takeaways Key Points In a chemical equilibrium, the forward and reverse reactions occur at equal rates, and the concentrations of products and reactants remain constant. A catalyst speeds up the rate of a chemical reaction, but has no effect upon the equilibrium position for that reaction. Key Terms chemical equilibrium : In a chemical reaction, the state in which both reactants and products are present at concentrations that have no further tendency to change with time.
Learning Objectives Duplicate the form of the equation for the thermodynamic equilibrium constant. The equilibrium state is independent of the direction from which it is approached. Most chemical reactions are reversible. What does this mean? It means that the products of a chemical reaction, under certain conditions, can be combined to re-form the reactants. In we learned mostly about reactions that proceed to completion. These reactions are considered irreversible because the energy that would be required to reverse the process of the forward reaction is prohibitive.
The number values for equilibrium constants are tied to the nature of reactants and products in a reaction. The number values for "K" are taken from experiments measuring equilibrium concentrations. The value of K indicates the equilibrium ratio of products to reactants. In an equilibrium mixture both reactants and products co-exist.
The term "favored" means that side of the equation has higher numbers of moles and higher concentrations than the other. What is the equilibrium concentration for NO 2 if the concentration of N 2 O 4 is 0.
Remember the equilibrium constant is just that, a constant.
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