| System Type | Example | Apparent Mass Change | Reason |
|---|---|---|---|
| Closed | Reaction in sealed container | No change | Nothing enters or leaves |
| Open — gas escapes | CaCO₃ decomposition | Mass decreases | CO₂(g) lost to atmosphere |
| Open — gas absorbed | Mg burning in air | Mass increases | O₂ taken from atmosphere into product |
This comparison covers Open vs Closed System — Apparent Mass Changes within Formulae, Equations and Conservation of Mass for GCSE Chemistry. Revise Formulae, Equations and Conservation of Mass in Quantitative Chemistry for GCSE Chemistry with 13 exam-style questions and 12 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 7 of 14 in this topic. Use this comparison to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Formulae, Equations and Conservation of Mass
Which of the following is the correct formula for oxygen gas?
Explain why mass is conserved in a chemical reaction.
Quick recall flashcards
Name the seven diatomic elements.
H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂
Mnemonic: Have No Fear Of Ice Cold Beer
State the law of conservation of mass.
In a chemical reaction, the total mass of the products equals the total mass of the reactants.
No atoms are created or destroyed — they are only rearranged.