Under what conditions do physical and chemical equilibria occur? When a physical change does not go to completion, a physical equilibrium is established between the forward and reverse changes. When opposing chemical changes take place at the same rate, a chemical equilibrium is reached.Click to see full answer. Considering this, why do some reactions not go to completion?Some cannot. Various factors can force a reaction not to reach equilibrium; instead, the reaction is said to go to completion. The phrase go to completion means that the forward direction—such as reaction (1) above—continues until all reactants are used up.Subsequently, question is, what is the name for a type of reaction that does not go all the way to completion but reaches an equilibrium? This equilibrium is dynamic in nature and is therefore called dynamic equilibrium. On the other hand, the chemical reaction in which the products formed do not combine to give the reactants are known as irreversible reactions. Also asked, how do you know if a reaction has gone to completion? You can tell by looking at the reaction. If it stops bubbling or steaming it is finished. It?s going to react and start bubbling. When it stops bubbling and fizzing, the reaction will be over.What happens when a reaction has reached equilibrium?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.