Question

during a lab investigation, students measured the mass of some substances before and after two chemical reactions. their observations are below.

	mass of reactants (g)	mass of products (g)
reaction 2	300.00 g	196.82 g

assuming the students did not make any errors, which state most likely explains the changes in mass after the two reactions?
a reaction 1 reacted with a gas in the air and reaction 2 released gas as a product
b reaction 1 lost products in the form of a solid and reaction 2 lost reactants due to combustion
c reaction 1 gained a liquid condensate on the outside of the beaker, and reaction 2 gained products from contamination
d reaction 1 had mass convert to thermal energy and reaction 2 lost mass in the form of evaporated liquid

Explanation:

In a chemical reaction, mass should be conserved according to the law of conservation of mass. If the mass of products is greater than reactants, a gas from the air likely reacted with the reactants. If the mass of products is less than reactants, a gas was likely released as a product. In Reaction 1, mass of products > mass of reactants, so a gas from air likely reacted. In Reaction 2, mass of products < mass of reactants, so a gas was likely released.

Answer:

A. Reaction 1 reacted with a gas in the air and Reaction 2 released gas as a product