Final answer:
Catalysts and enzymes are substances that speed up chemical reactions without being permanently altered. Atoms are rearranged, but not created or destroyed, preserving mass. Reversible reactions at equilibrium also don't lead to permanent alterations in amounts of reactants or products.
Step-by-step explanation:
Catalysts are not permanently altered during the course of a reaction. In chemical reactions, catalysts, including enzymes, are substances that increase the rate of the reaction without being consumed or permanently altered themselves. They work by lowering the activation energy required for the reaction to proceed, allowing it to occur more quickly or at a lower temperature.
According to the conservation of matter, atoms are neither created nor destroyed in a chemical reaction, but are rearranged to form new substances. This explains why the mass of the reactants is equal to the mass of the products in a balanced chemical equation. Reactions can often be reversible, and when they reach equilibrium, they remain balanced with no net change in the amounts of reactants or products as long as external conditions do not change.
It is also noteworthy that in a chemical equation, spectator ions may appear in the equation but are not a direct part of the reaction process and are not altered, so they are not included in the net ionic equation. These ions are present in the solution but they do not experience any net chemical change.