Gas Evolution Experiment Analysis

Steps:

• Identify that SO2 gas is produced and escapes the flask during the reaction.
• Recognize that the total mass of the flask and contents includes the gas before it escapes.
• Note that as SO2 is produced and collected separately, it leaves the system, reducing the flask's mass.
• Conclude that continuous gas production causes ongoing mass decrease until the reaction ends.

Why B is correct:

• Conservation of mass dictates that escaping gas reduces the measurable mass of the reaction mixture.

Why the others are wrong:

• A: SO2 is soluble in water, preventing effective collection by water displacement.
• C: Reaction rate typically decreases over time as reactants are consumed.
• D: Not enough information without the graph to confirm reaction status at eight minutes.

Final answer: B