Calculate the equilibrium concentrations at 25 °C for the reaction in Problem 15.84 if the initial concentrations are 3N2O44 = 0.0200 M and 3NO24 = 0.0300 M.

Verified step by step guidance

1. Identify the balanced chemical equation for the reaction. For example, if the reaction is \( N_2O_4 \rightleftharpoons 2NO_2 \), write it down.
2. Write the expression for the equilibrium constant \( K_c \) using the balanced equation. For the example reaction, \( K_c = \frac{[NO_2]^2}{[N_2O_4]} \).
3. Set up an ICE (Initial, Change, Equilibrium) table to track the concentrations of reactants and products. Use the initial concentrations given: \([N_2O_4]_0 = 0.0200\, M\) and \([NO_2]_0 = 0.0300\, M\).
4. Define the change in concentration using a variable, such as \( x \), and express the equilibrium concentrations in terms of \( x \). For example, if \( N_2O_4 \) decreases by \( x \), then \( NO_2 \) increases by \( 2x \).
5. Substitute the equilibrium concentrations into the \( K_c \) expression and solve for \( x \). Use this value to find the equilibrium concentrations of all species.

Key Concepts

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. At this state, the system is dynamic, meaning that reactions continue to occur, but there is no net change in concentration. Understanding this concept is crucial for calculating equilibrium concentrations.

Equilibrium Constant (K)

The equilibrium constant (K) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium, each raised to the power of their coefficients in the balanced equation. It provides insight into the position of equilibrium and helps predict how changes in concentration, temperature, or pressure will affect the system.

ICE Table (Initial, Change, Equilibrium)

An ICE table is a tool used to organize the initial concentrations, the changes in concentrations as the reaction proceeds, and the equilibrium concentrations of reactants and products. By setting up an ICE table, one can systematically calculate the equilibrium concentrations based on the initial conditions and the stoichiometry of the reaction.