Question

In the lab, a student took a piece of aluminum foil weighing 0.50 g and ripped it into small pieces. They then took 5.00 g of copper chloride and crushed it in the mortar and pestle. After the copper chloride was crumbled it was dissolved in 100.0 mL of water in a beaker. The student weighed the substances in the beaker and found the mass to 205.00 g. The students then placed the aluminum foil pieces in the beaker and waited 2 minutes. The student noted that the beaker felt warmer than before they added the aluminum foil pieces. The student also noted that the pieces of aluminum foil turned an orangish color and they noted the presence of bubbles. The final mass of the reaction mixture was 201.00 g. Was the law of conservation of matter followed in this situation? Why or why not?

Answer 1

The law of conservation of matter states that matter cannot be created or destroyed. Although the mass decreased after the reaction of aluminum with copper chloride, this does not violate the law, as the system was not closed and gases likely escaped.

Step-by-step explanation:

The student's question is whether the law of conservation of matter was followed in the reaction between aluminum foil and copper chloride dissolved in water, as evidenced by a change in the mass of the reaction mixture. Initially, the substances weighed 205.00 g, and after the reaction, the weight was 201.00 g. According to the law of conservation of matter, the mass of the reactants should equal the mass of the products in a closed system.

In this scenario, however, it is likely that gases were released during the reaction (as indicated by the presence of bubbles), which would escape the beaker and lead to a loss in mass. Thus, the system is not closed, and the decrease in mass does not violate the law, as the matter was not destroyed but rather changed to a gaseous form that escaped the beaker.

Examples provided in the explanation, such as the combustion of magnesium in the air producing magnesium oxide with the same mass as the original magnesium and Antoine Lavoisier's experiment with tin and air, reiterate this principle by demonstrating that when the system is closed, the mass before and after the reaction remains the same.