Question

A group of students heated magnesium ribbon over a Bunsen burner until it burned, reacting with the oxygen in the air. One student heated the magnesium until all the metallic solid was replaced by a dull grey solid residue. The students’ data table is pictured below, as well as some photos they took during the experiment. Note: the crucible is a small clay container that contains a large amount of heat. The lid is placed loosely on the crucible while it is heating, allowing air in but keeping magnesium from escaping. Assuming the magnesium ribbon only reacted with the oxygen in the air, which of the following would best describe the reaction taking place? The mass of the magnesium ribbon is the same as the mass of the residue because even though the oxygen in the air reacted with the magnesium, it doesn't matter because air has no mass. The mass of the magnesium ribbon is more than the mass of the residue because the oxygen in the air escapes and cannot be counted as mass. The mass of the magnesium ribbon is less than the mass of the residue because the oxygen in the air must be included as a reactant and has mass.

Answer 1

The reaction taking place is the formation of magnesium oxide (MgO) when magnesium ribbon reacts with oxygen in the air. The mass of the magnesium ribbon is less than the mass of the residue because the oxygen in the air must be included as a reactant and has mass.

Step-by-step explanation:

The reaction taking place when magnesium ribbon reacts with oxygen in the air is the formation of magnesium oxide (MgO). The mass of the magnesium ribbon is less than the mass of the residue because the oxygen in the air must be included as a reactant and has mass. When magnesium reacts with oxygen, the magnesium atoms lose electrons and are oxidized, while the oxygen atoms gain electrons and are reduced. The resulting product, magnesium oxide, is a crumbly white powder.