Question

Ms. Block's students are studying chemical reactions as well as the law of conservation of matter. A classic reaction occurs when a metal is added to hydrochloric acid. Miguel and Kai are about to add 30g of hydrochloric acid (HCl) to 30g of magnesium (Mg) in a large test tube. How could you adapt the boys experimental design so they would definitely be testing the law of conservation of matter?
A) The boys could use less hydrochloric acid to produce less gas bubbles.
B) The boys should use a container, such as a flask, that is larger than a test tube.
C) The boys could cover the end of the test tube with a balloon to capture the escaping gas.
D) One of the boys could place a hand over the end of the test tube to create a closed system.

Answer 1

The answer is; C

Conservation of matter in a reaction means that the mass of matter in the products is equal to the mass of the reactants. Energy/matter cannot be created or destroyed but converted from one form to another.

An expanding balloon with the increased evolution of gas is a good visible practical sign in the experiment on the conservation of matter in the reaction. As the magnesium disappears with an increased input of hydrochloric acid, the balloon gets bigger showing that more hydrogen is evolved from the reaction;

2HCL + Mg  MgCl2 + H2  

Answer 2

Answer:

A

Explanation:

out of  A. 8g of hydrogen gas escaped from the test tube.

               B)8g of magnesium disappeared during the reaction.

        C) Miguel and Kai were not very proficient at using the beam balance.

               D) 8g of the mass produced the heat the boys felt at the end of the experiment.