A student sets up an experiment as shown to test the law of conservation of mass. A mixture of copper and sulfur is heated to produce solid copper sulfide and gaseous sulfur dioxide, which is collected in a balloon. To ensure the data collected are valid, the student should

While it may seem important to measure the mass quickly, allowing the mixture to cool down does not inherently affect the mass of the reactants or products. The total mass should remain constant regardless of the temperature, and taking measurements after cooling may introduce errors related to the handling of the materials rather than affecting the fundamental conservation of mass principle.

This approach is incorrect because the mass of the balloon needs to be included in both measurements to ensure an accurate comparison. Ignoring the balloon's mass after heating would result in an incomplete assessment of the total mass, leading to erroneous conclusions about the conservation of mass.

Removing the balloon would cause the loss of gaseous products, which would invalidate the experiment's results since the reaction products would not be accounted for in the mass measurement. This action directly contradicts the law of conservation of mass, which posits that mass cannot be created or destroyed in a closed system.