Mass Changes when a Reactant or Product is a Gas Flashcards
All 7 cards in this deck
Why does the mass of the solid increase when a metal is heated in air?
Oxygen atoms from the air join the metal to form the oxide, so the oxide contains the mass of the metal plus the mass of the oxygen.
Why does the mass in an open flask decrease when a metal carbonate is thermally decomposed?
Carbon dioxide gas is produced and escapes into the atmosphere, leaving only the metal oxide as solid.
True or false? An apparent loss of mass in an open flask shows that atoms have been destroyed.
False. A gaseous product has escaped from the flask; no atoms are lost or made.
What happens to the mass of an open flask when an acid reacts with a carbonate, and why?
The mass decreases, because carbon dioxide is produced and escapes from the flask.
In terms of particles, why can a reaction in a non-enclosed system appear to gain mass?
Particles of a gaseous reactant (e.g. oxygen) from the air are added to the solid, and their mass was not counted at the start.
True or false? If magnesium is burned in a sealed container, the total mass stays the same.
True. No gas can enter or escape, so the total mass of reactants equals the total mass of products.
How do you use a balanced equation to predict whether mass rises or falls in an open container?
e.g.
- Find any gases in the equation: .
- Decide if the gas is a reactant (enters) or product (escapes): it is a product.
- Gas escaping means mass falls: the mass in the container decreases.