Describe the final common pathway for blood coagulation.

1. Pure chemical corrosion occurs when a metal reacts with a chemical substance in its environment, such as acids or alkalis. This reaction causes the metal to break down and corrode. An example of pure chemical corrosion is the reaction between iron and acid rain. Acidic pollutants in the air react with iron to produce iron oxide, which weakens the metal and causes it to corrode. 2. Pure electrochemical corrosion occurs when two or more metals that are in contact with each other in the presence of an electrolyte or a conductive solution, such as saltwater. One metal acts as the anode, which undergoes oxidation and releases electrons, while the other metal acts as the cathode, which undergoes reduction and accepts electrons. This creates an electrochemical cell, which leads to corrosion of the anode. An example of pure electrochemical corrosion is the corrosion of the zinc coating on steel structures in marine environments. The zinc acts as the sacrificial anode, protecting the steel from corroding, but as the zinc corrodes, the steel becomes exposed and corrodes as well.