vacuum-insulated reaction flask<>approximates<>the condition of a isolated system$$$neither matter nor heat<>can be exchanged<>a isolated system
The condition that the system is mechanically isolated is necessary in order to ensure it does not exchange energy with any external object besides the heat bath.
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?