Q1. Why silver, gold and platinum do not undergo corrosion?

Silver, gold, and platinum are considered corrosion-resistant metals due to their unique properties and chemical behaviors. Several factors contribute to their resistance to corrosion:

1. Chemical Stability: These metals have a high level of chemical stability, meaning they are less reactive with most substances in the environment. They are relatively inert, which reduces their susceptibility to oxidation or corrosion.
2. Noble Metals: Silver, gold, and platinum belong to the group of noble metals, characterized by their inertness and resistance to chemical reactions. They have a stable configuration of electrons in their outermost energy levels, making them less prone to forming compounds with other elements.
3. Lack of Reactivity: These metals do not easily react with moisture, oxygen, or common atmospheric gases, which are primary contributors to corrosion in many other metals. Their resistance to tarnishing or rusting is due to the minimal tendency to undergo oxidation.
4. Chemical Inertness: Even in harsh environments or exposure to various chemicals, these metals maintain their integrity and do not easily degrade or corrode. This makes them highly valuable for applications where durability and resistance to corrosion are essential, such as in jewelry or electronic components.

Q2. Why zinc gives better protection for the corrosion than tin?

Zinc provides better corrosion protection than tin due to several key factors:

1. Galvanic Protection: Zinc exhibits galvanic protection, which means it can sacrificially corrode to protect other metals that may be in contact with it. When zinc corrodes, it forms zinc oxide or zinc hydroxide, which creates a protective barrier on the metal's surface, preventing further corrosion. This sacrificial behavior makes zinc an excellent choice for galvanized coatings on steel, where it corrodes preferentially to protect the underlying steel.

<aside> 💡 Zinc offers better corrosion protection than tin because it can sacrificially corrode, creating a protective barrier on its surface to shield underlying metals. Zinc has a more negative electrode potential and forms effective corrosion products, while tin is less sacrificial and less effective at corrosion protection.

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1. More Negative Electrode Potential: Zinc has a more negative electrode potential (around -0.76 V) compared to tin (around -0.14 V). This means that in a galvanic cell with tin and zinc, zinc will be the anode (where corrosion occurs) and tin will be the cathode. The more negative potential of zinc makes it more willing to undergo corrosion and protect the tin.
2. Formation of Protective Layers: Zinc can form stable corrosion products like zinc oxide and zinc hydroxide, which act as protective layers on its surface. These layers hinder further corrosion by blocking the access of oxygen and moisture to the underlying zinc.

In contrast, tin does not exhibit the same level of sacrificial protection as zinc. Tin's electrode potential is less negative, so it is less likely to corrode and provide protection to other metals in contact with it. Additionally, tin forms less effective corrosion products, making it more susceptible to continued corrosion.

Overall, zinc's ability to sacrificially corrode, its more negative electrode potential, and the formation of protective corrosion products make it a superior choice for corrosion protection compared to tin in many practical applications, such as galvanized coatings for steel structures or zinc-based anodes in corrosion prevention systems.

Q3. How is the area of anode and cathode influence the rate of corrosion?

The area of the anode and cathode in a corrosion cell can significantly influence the rate of corrosion. This relationship is described by Faraday's law of electrolysis, which also applies to corrosion. Here's how it works:

1. Anode Area:
   • The anode is the part of the metal where corrosion occurs, leading to the release of metal ions into the electrolyte.
   • A larger anode area means more metal surface is available for corrosion to take place.
   • With a larger anode area, there are more active sites for the corrosion reaction to occur simultaneously, resulting in a higher corrosion rate.
2. Cathode Area:
   • The cathode is where reduction occur, often involving the consumption of electrons and the neutralization of metal ions.
   • A larger cathode area can facilitate the reduction reactions more effectively.
   • If there is an excess of electrons available at the cathode, it can drive the corrosion process at the anode, increasing the corrosion rate.

<aside> 💡 In corrosion, the rate is influenced by the area of the anode and cathode. A larger anode area leads to a higher corrosion rate, as more metal surface is available for corrosion. Additionally, a larger cathode area with excess electrons can accelerate corrosion at the anode. Both anode and cathode areas play vital roles in determining corrosion rates.

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