Explain a reason Kevin used a stopper in his experimental setup AND what could happen to the mass of the products of this reaction if the stopper were not used.
Kevin used a stopper in his experimental setup to seal off the reaction vessel and prevent the escape of any gases or vapors produced during the reaction. If the stopper were not used, the mass of the products of the reaction could be underestimated because some of the products may escape from the reaction vessel. This could lead to inaccurate results and conclusions regarding the reaction. By using a stopper, Kevin ensured that all the products remained in the reaction vessel and were accounted for in the measurement of the mass.
