Not necessarily. A system in dynamic equilibrium has achieved a state where the forward and reverse reactions occur at the same rate, and concentrations of reactants and products remain constant. However, this doesn't imply that the system is at its lowest energy state or thermodynamic equilibrium. The position of dynamic equilibrium is influenced by kinetics, i.e., the rate of reactions, and might not correspond to the most stable thermodynamic state of the system. While thermodynamic equilibrium ensures the system is at its lowest energy state, dynamic equilibrium is more about balanced rates of opposing processes.

Yes, dynamic equilibrium can be achieved in a system with only one reactant if that reactant undergoes a dissociation or dimerisation reaction. For example, consider acetic acid, which can partially dissociate into acetate ions and hydrogen ions in an aqueous solution. Initially, as the dissociation reaction proceeds, the concentration of acetic acid decreases, while the concentration of the acetate and hydrogen ions increases. Over time, these ions can recombine to form acetic acid, and an equilibrium will be established between the dissociated ions and the undissociated acid. Both the forward (dissociation) and reverse (recombination) reactions occur at the same rate at equilibrium.

Dynamic equilibrium is not a permanent state. It can be disrupted by changes in external conditions such as temperature, pressure, or concentration of reactants or products. For instance, if additional reactants are introduced into a system at equilibrium, the forward reaction rate might increase to consume the added reactants, shifting the position of equilibrium. Similarly, changes in temperature can favour either the endothermic or exothermic direction of a reversible reaction, leading to a new equilibrium position. The system will always respond to these changes to re-establish a balance, as described by Le Chatelier's principle.

Visually identifying a system in dynamic equilibrium can be challenging since there's no net observable change in the concentration of reactants and products. However, one could use indicators or tracers. For instance, a colour-changing indicator might be used in a solution, where a change in colour signifies a shift away from equilibrium. If the colour remains constant, it indicates the system is likely at equilibrium. Additionally, modern techniques like spectroscopy can be employed. In a system at dynamic equilibrium, the absorbance or emission spectrum of the reactants and products would remain constant over time, reflecting their unchanging concentrations.

In a closed system, when the reaction starts, the concentration of the reactants is at its maximum. As the forward reaction progresses, reactants are converted into products, which means their concentrations decrease. A decrease in reactant concentration results in a reduced frequency of effective collisions between reactant molecules, slowing down the forward reaction rate. Conversely, as more products are formed, the rate of the reverse reaction increases due to an increase in product concentration. Eventually, the rates of the forward and reverse reactions equalise, leading to dynamic equilibrium. The balance reached is a result of decreasing reactant concentration and increasing product concentration until they stabilise.