The water in a beaker has a mass of 18g. Electricity is passed through the water for two hours. Afterward the water has a mass of only 16g. What happened to the missing mass?
The water heated up due to the electrical current going through it, and some of it evaporated. This is probably not a case of electrloysis (separation into H2 and O2). That requires a special apparatus.
The water heated up due to the electrical current going through it, and some of it evaporated
The missing mass of 2g might have been lost through evaporation. As electricity was passed through the water, it could have heated up and some of it might have turned into water vapor and escaped into the surrounding environment.
To determine what happened to the missing mass, let's analyze the provided information.
First, we know that the initial mass of the water in the beaker was 18g, and after two hours of passing electricity through it, the mass decreased to 16g.
Given this information, we can rule out the possibility of the missing mass being a result of electrolysis, as electrolysis refers to the separation of a compound into its constituent elements by passing an electric current through it.
Instead, the most plausible explanation is that some of the water evaporated due to heating caused by the electric current passing through it. When water is heated, the energy is transferred to the water molecules, increasing their kinetic energy and causing them to move faster. As a result, some water molecules gain enough energy to break the intermolecular bonds holding them together and transform into a gaseous state, resulting in evaporation.
In this scenario, the missing mass of 2g can be attributed to the water that evaporated during the two hours of electricity passing through it.