vacuum-insulated reaction flask<>approximates<>the condition of a isolated system$$$neither matter nor heat<>can be exchanged<>a isolated system
Whenever a system can exchange either heat or matter with its environment, an entropy decrease of that system is entirely compatible with the second law.
A sealed, vacuum-insulated reaction flask approximates the condition of a isolated system, in which neither matter nor heat can be exchanged between system and surroundings.
A sealed, vacuum-insulated reaction flask approximates what condition, in which neither matter nor heat can be exchanged between system and surroundings?