Question

After the three days, what happens in each test tube? why? what is necessary for rust to occur? how does this activity demonstrate the fate of oxygen in earthâs early atmosphere, when iron in the oceans was still removing oxygen from the air?

Answer 1

Rusting requires iron, oxygen, and water, and results in the formation of iron oxides. The early Earth's iron-rich oceans removed oxygen from the atmosphere. Experiments with test tubes and iron nails can demonstrate the principles of rust formation and relate to the early atmospheric conditions.

Step-by-step explanation:

Rusting is a form of corrosion that particularly affects iron and its alloys. This process occurs when iron is exposed to oxygen and water, leading to the formation of iron oxides, commonly called rust, represented by the chemical formula Fe2O3·xH2O. The experiment in the question likely involves test tubes with iron nails or similar iron-containing material that exhibits rust formation when exposed to oxygen and moisture over the course of three days.

To form rust, three essential components are necessary: iron, oxygen, and water. The presence of electrolytes, such as salt in water, can accelerate the process. During the early Earth's atmosphere, lower levels of dissolved oxygen in oceans allowed for more soluble iron ions (Fe2+) available in water. This abundance of Fe2+ would have been oxidized as oxygen levels rose, aiding in the removal of oxygen from the atmosphere until it reached saturation, allowing for the increment in atmospheric oxygen that we observe today. This process mirrors the removal of oxygen as seen in the test tubes where iron in the presence of oxygen and moisture rusts, demonstrating how early Earth's oceans could have acted as a sink for the free oxygen before the levels in the atmosphere increased significantly.

Answer 2

The situation would be that, in a sealed tube,  there are 3 to 4 nails inside and a certain amount of calcium chloride was added. After three days, there will be no changes to be observed in the first tube since the oxygen is not enough to initiate a change and there is no presence of water. For the second test, the same situation is made but boiling water was filled in the tube. For this, no changes would still be observed since there is no moisture. For the last test, the same situation as the first but it is filled halfway with water. After 3 days, rust would be observed on the nails. In order for rust to happen, there should be water and oxygen. The oxygen in the early atmosphere of the Earth would react with iron present in the oceans thus producing iron ores.