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GCSE Chemistry · key term
A system from which matter, including a gas, can enter or leave during a reaction.
Used by AQA, Edexcel and OCR
Specification 4.3.1.3 · Paper 1
Revise: Mass Changes in Gas ReactionsNevertheless, a balance may show a change during a reaction in a non-enclosed system, such as an open crucible. This does not mean that conservation of mass has failed. The balance measures only the container and the substances currently on it.
Specification 1.47 · Paper 1, Paper 2
A system that can exchange matter, such as a gas, with its surroundings.
Revise: Law of Conservation of MassA non-enclosed system, such as an open flask, can exchange matter with its surroundings. The law of conservation of mass still applies, but the balance may not be measuring every reactant and product.
Specification C3.1j · Paper 1 (Foundation), Paper 3 (Higher)
A reaction system that can exchange substances, including gases, with its surroundings.
Revise: Mass Changes in ReactionsA non-enclosed system allows substances to pass between the reaction mixture and its surroundings. If a container sits on a balance, the reading includes the container and what remains in it. It does not include gas that has escaped into the air, or gas in the air before it enters the container.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
A system that allows substances, including gases, to enter or leave during a reaction.
Revise: Mass changes in non-enclosed systemsA non-enclosed system allows substances to move between the container and its surroundings. Gas particles can enter from the air or escape into it. If they cross that boundary, the mass of the material on the balance changes without any change in the total mass of the matter involved.
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