Final answer:
The final concentration of D at equilibrium cannot be calculated without additional details about the balanced chemical equation, the equilibrium constant (Keq), or the changes in concentration as the system reaches equilibrium.
Step-by-step explanation:
To determine the final concentration of D at equilibrium, we must use information about the reaction dynamics and the equilibrium constant (Keq). Since the exact reaction and compounds involved are not provided in the question, we can't calculate the concentration of D without additional data.
Generally, to calculate the equilibrium concentrations, we would use the initial concentrations of reactants and the equilibrium constant to set up an equation that reflects the stoichiometry of the reaction, often referred to as an ICE table (Initial, Change, Equilibrium). For instance, for a hypothetical reaction A + B ⇌ C + D, and knowing Keq, we can set up an equation like Keq = [C][D]/[A][B] and solve for the unknown, assuming the reaction has proceeded to equilibrium and initial concentrations or changes in concentration for some species are known.
In conclusion, without the specific balanced chemical equation and Keq value, or details on how the system changes as it approaches equilibrium, the final concentration of D cannot be accurately determined from the information provided.