Q1: Corrosion rate can not be lowered by reducing the __________ of the corroding medium.

ANS:A - concentration

1. Chemical Reaction: Corrosion is typically a chemical reaction between the metal surface and the surrounding environment. In many cases, corrosion occurs due to the presence of corrosive agents such as acids, salts, or oxygen.
2. Reaction Rate: The rate of corrosion is often influenced by the rate of the chemical reactions occurring between the metal and the corrosive agents. These reactions may involve the dissolution of the metal ions into the surrounding medium or the formation of corrosion products on the metal surface.
3. Mass Transport: The concentration of corrosive agents in the medium affects the mass transport of reactants to the metal surface. Higher concentrations provide more reactant molecules, increasing the likelihood of collisions with the metal surface and promoting corrosion reactions.
4. Reducing Concentration: When the concentration of corrosive agents in the medium is reduced, there are fewer reactant molecules available for the corrosion reactions. As a result, the rate of mass transport to the metal surface decreases, and the corrosion rate may slow down.
5. Equilibrium Considerations: However, reducing the concentration of corrosive agents does not necessarily eliminate corrosion entirely. Corrosion reactions may still occur, albeit at a slower rate, as long as there are sufficient reactants present to sustain the reaction. In some cases, corrosion may even continue at a significant rate, especially if other factors such as temperature or velocity are conducive to corrosion.
6. Effectiveness: While reducing the concentration of corrosive agents can sometimes lower the corrosion rate, it may not always be effective, especially if other factors influencing corrosion are not addressed. For example, factors such as temperature, velocity, or the presence of other corrosive species may still contribute to corrosion even at lower concentrations.

In summary, while reducing the concentration of the corroding medium can potentially lower the corrosion rate by decreasing the availability of reactants, it may not always eliminate corrosion entirely and may need to be combined with other corrosion control measures for effective protection against corrosion.