Question

doug is testing out the following reaction: na2co3 + 2hcl → 2nacl + h2o + co2. he combines sodium carbonate with hydrochloric acid in a 100 ml graduated cylinder and covers the mouth of the graduated cylinder with a balloon. doug fills out the data table.

substance/material\tmeasurement
mass of sodium carbonate\t2.5 g
mass of empty graduated cylinder\t72.5 g
mass of graduated cylinder with hcl\t88.8 g
mass of empty balloon\t0.4 g
mass of final experiment\txxx g

in order to show evidence supporting the law of conservation of mass, what should doug find as the final mass, and why?
a 18.9 g, because only the mass of the products should be accounted for, not the equipment.
b 19.2 g, because the mass of the products and the balloon should be accounted for.
c 75.4 g, because this mass accounts for all equipment and products in the reaction.
d 91.7 g, because this mass accounts for all equipment, reactants, and products created in the reaction.

Explanation:

Step1: Calculate total mass of reactants and equipment

The mass of sodium carbonate is $2.5$ g. The mass of the graduated - cylinder with HCl is $88.8$ g and the mass of the empty balloon is $0.4$ g.
Total mass before reaction = mass of sodium carbonate+mass of graduated - cylinder with HCl+mass of empty balloon
$=2.5 + 88.8+0.4$
$=91.7$ g

Step2: Apply Law of Conservation of Mass

According to the Law of Conservation of Mass, the total mass of the reactants and equipment before the reaction is equal to the total mass of the products and equipment after the reaction.

Answer:

D. 91.7 g, because this mass accounts for all equipment, reactants, and products created in the reaction.