In an isolated system, what is true about changes in internal energy and mass?

In an isolated system, the total internal energy and mass remain constant due to the conservation laws applicable to such systems. The principle of conservation of energy states that energy cannot be created or destroyed; it can only change forms. Therefore, any changes that might occur in the internal energy due to work done or heat exchanged are balanced by corresponding changes within the system, leading to no net change in internal energy (ΔE = 0).

Similarly, the law of conservation of mass states that the mass of an isolated system remains constant. No mass can enter or leave the system, which means that the total mass within the system does not change over time (ΔM = 0).

Thus, both internal energy (ΔE) and mass (ΔM) in an isolated system will maintain constant values, meaning both will show no changes. This understanding is fundamental to thermodynamics and physical chemistry concepts, providing a basis for more complex behaviors in closed systems and the transition of energy and matter under different conditions.