Question

17 two students are conducting an experiment in a lab. as two liquid substances were mixed, the students observed a color change and the production of bubbles. when the re (a) part a: which of the following masses could be the total mass of the substances before they were mixed together? a 180.1 g b 271.2 g c 354.6 g d 360.1 g (b) part b: which of the following statements could be used to explain your choice in part a? a the total mass before the reaction must always be the same as the total mass after the reaction in an open - system. b the total mass before the reaction is greater because some of the gaseous product escaped into the atmosphere reducing the mass of the product. c if there are 2 reactants, then the mass of each reactant must be ½ the mass of the product. d when 2 liquid reactants form a solid product, the mass of the liquid reactants is always less than the solid products.

Explanation:

Step1: Understand mass - conservation in open systems

In an open - system chemical reaction where gas is produced (bubbles are observed), gas can escape into the atmosphere. According to the law of conservation of mass, the total mass before the reaction is equal to the total mass after the reaction in a closed system. But in an open system, the mass of the products measured may be less than the mass of the reactants because some gaseous products escape.

Step2: Analyze Part A

The mass shown on the scale (354.6 g) is the mass of the remaining substances after the reaction. Since gas escaped during the reaction, the total mass of the substances before the reaction must be greater than 354.6 g. Among the options, 360.1 g is greater than 354.6 g.

Step3: Analyze Part B

The correct explanation for Part A is that the total mass before the reaction is greater because some of the gaseous product escaped into the atmosphere reducing the mass of the product.

Answer:

Part A: D. 360.1 g
Part B: B. The total mass before the reaction is greater because some of the gaseous product escaped into the atmosphere reducing the mass of the product.