77. 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
Answer: A
Using the same balance for determining the mass before and after heating ensures consistency in measurements.
To validate the data collected in this experiment, it is crucial to use the same balance for measuring the mass of the substances before and after heating. This consistency eliminates variations that could arise from using different balances, thus ensuring accurate comparisons.
A) Use the same balance for determining the mass before and after heating.
This option is correct because using the same balance eliminates discrepancies that could occur due to differences in calibration or precision between different balances. Maintaining uniformity in measurement tools is essential for achieving reliable and valid data in experiments.
B) Determine the mass of the mixture before it has a chance to cool.
This option is incorrect because while measuring the mass before cooling is important, it does not address the potential inconsistencies introduced by using different balances. Additionally, the mass should ideally be measured once the substances have stabilized to ensure accuracy.
C) Include the mass of the balloon in the total mass only after heating.
This option is incorrect because the mass of the balloon should consistently be accounted for in both measurements to maintain accuracy. Excluding it in one measurement could lead to erroneous conclusions about the conservation of mass.
D) Remove the balloon after heating and before determining the mass a second time.
This option is incorrect as it would lead to an incomplete measurement. Removing the balloon would alter the system being analyzed, making it impossible to accurately determine the total mass after the reaction.
Conclusion
In summary, the correct answer is option A, as using the same balance is critical for ensuring accurate and comparable measurements in the experiment. All other options either overlook the importance of consistent measurement tools or introduce variables that could compromise the validity of the data collected.