Question

part b
if this same reaction were carried out in an open container instead of a closed flask, how would the measured mass most likely change, and why?
the mass would increase because gases from the air would enter the container.
the mass would decrease because atoms are destroyed when gas forms.
the mass would decrease because carbon dioxide gas could escape.
the mass would stay the same because the number of atoms in the products always equals the number in the reactants.

Explanation:

In a chemical reaction, mass is conserved according to the law of conservation of mass. However, if a gas is produced in an open - container reaction and can escape, the measured mass will decrease. Atoms are not destroyed in a chemical reaction (violates the law of conservation of mass). If gases from the air enter, it's not a common scenario for a typical reaction without specific conditions favoring gas influx. The key here is that carbon - dioxide gas (if produced) can escape in an open container, reducing the measured mass.

Answer:

The mass would decrease because carbon dioxide gas could escape.