Open systems exchange matter and energy, closed exchange only energy, isolated exchange neither.
Practise Thermodynamics & Energetics All Thermodynamics & Energetics topics
Systems are classified by what crosses their boundary. An open system exchanges both matter and energy with its surroundings, like an uncovered beaker of boiling water that loses vapor to the air. A closed system exchanges only energy, so the amount of material inside stays fixed, as in a sealed flask resting in a water bath. An isolated system exchanges neither matter nor energy, an idealization approximated by a well-insulated vacuum flask. The classification determines which conservation statements apply directly to the system and whether its composition can change during a process.
Key ideas: Ask two questions to classify a system: can matter cross the boundary, and can energy cross it? Yes to both gives open, energy only gives closed, and neither gives isolated. Living organisms are open systems, a sealed ampoule in a bath is closed, and the universe as a whole is treated as isolated. Only in an isolated system is the total energy strictly constant without any accounting of transfers.
Common mistakes and connections: Students often call a stoppered flask isolated because nothing leaves it, forgetting that heat still crosses the glass. A thermos is only approximately isolated, since it slowly loses heat. The classification connects to the second law, which is usually stated for isolated systems.
Number of quantities that can cross the boundary: an open system exchanges matter and energy, a closed one only energy, an isolated one neither. The interactive lesson shows this as a live animation or chart.
A stoppered flask sitting in a water bath is a closed system, because heat passes through its walls but no material leaves.
Open systems exchange matter and energy, closed exchange only energy, isolated exchange neither.
Open Closed Isolated Systems is a beginner topic in Thermodynamics & Energetics. It needs no earlier chemistry lessons and is a good starting point.
Study these earlier topics in Thermodynamics & Energetics first: System and Surroundings.
The next topics in Thermodynamics & Energetics are State Function and Path Function.
Yes. The interactive lesson includes a self-check question on Open Closed Isolated Systems, and the Thermodynamics & Energetics quiz draws on every topic in this area.
Open Closed Isolated Systems is topic 2 of 91 in Thermodynamics & Energetics.