Question

For another researcher's data the starting mass of apparatus + solid was 113.249 g. After the reaction was complete the apparatus was reweighed. The resulting mass was 113.276 g. Which of the following could have caused the mass gain?

Select all that apply
Group of answer choices
The apparatus had a gas leak and room air could enter the apparatus.
The apparatus picked up extra water droplets between weighings
They forgot to weigh the mass of the gas-generating solid before the reaction.
Matter was created in the reaction.

Answer 1

Possible reasons for the observed mass gain include a gas leak allowing air to enter the apparatus, absorption of water droplets between weighings, or an unaccounted starting mass of the solid. The conservation of mass principle dictates that matter is not created during the reaction.

Step-by-step explanation:

In the context of this experiment, a few phenomena could explain the observed increase in mass of the apparatus after the reaction. First, if the apparatus had a gas leak, the entrance of room air could increase the total mass measured. Second, if the apparatus picked up extra water droplets between weighings, this would also cause a gain in mass as water from the air gets absorbed onto the surface or as condensate. Lastly, a common laboratory issue could be that they forgot to weigh the mass of the gas-generating solid before the reaction, underestimating the starting mass. The notion that 'matter was created in the reaction' would violate the law of conservation of mass, which states that mass cannot be created or destroyed in an isolated system.