Problem 37 - Chemistry The Molecular Science

Question

Compare the action of concentrated nitric acid on silver with that on gold.

Step-by-Step Solution

Answer

Concentrated nitric acid reacts with silver, producing silver nitrate, while it does not react with gold.

Step 1: Chemical Reaction with Silver

When concentrated nitric acid (HNO₃) comes into contact with silver (Ag), a chemical reaction occurs. Silver reacts with the nitric acid to form silver nitrate (AgNO₃), nitrogen dioxide (NO₂), and water (H₂O). The balanced chemical equation for this reaction is: \[ 3Ag + 4HNO_3 ightarrow 3AgNO_3 + 2NO_2 + 2H_2O \] This reaction is characterized by the evolution of nitrogen dioxide gas, which appears as brown fumes.

Step 2: No Reaction with Gold

Gold (Au), however, does not react with concentrated nitric acid. Gold is a noble metal and is chemically inert to nitric acid due to its high resistance to oxidation and corrosion. This lack of reaction is one of the reasons gold is valuable and long-lasting, as it does not tarnish or corrode when exposed to common acids, including nitric acid.

Step 3: Summary of Observations

In summary, concentrated nitric acid reacts with silver, producing silver nitrate and brown nitrogen dioxide gas, but it does not react with gold, leaving it unchanged. This is due to silver being more reactive than gold during the chemical process.

Key Concepts

Nitric Acid

Nitric acid (HNO₃) is a powerful and corrosive mineral acid known for its strong oxidizing properties. When it interacts with reactive metals, vigorous reactions often occur.

• It is commonly used in laboratories and industrial applications.
• Plays a significant role in the production of fertilizers, explosives, and even in the metallurgy of certain metals.

In chemistry, nitric acid is known for its ability to donate nitrate ions, making it a key player in various chemical reactions. Its interaction with different metals varies, leading to the formation of oxides and nitrates.

Silver Chemistry

Silver (Ag) is a metallic element that reacts readily with substances like nitric acid. When silver meets concentrated nitric acid, a chemical reaction occurs, forming silver nitrate (AgNO₃).

• The reaction releases nitrogen dioxide (NO₂), a brown gas.
• Water (H₂O) is also produced during the process.

The balanced chemical equation for this reaction is: \[ 3Ag + 4HNO_3 \rightarrow 3AgNO_3 + 2NO_2 + 2H_2O \] Silver's reactivity with nitric acid highlights its chemical properties, demonstrating how it transforms when exposed to strong acids.

Gold Inertness

Gold (Au) is renowned for its lack of reaction with most chemicals, including concentrated nitric acid. Its inertness is a hallmark of its status as a noble metal. Gold's resistance to nitric acid is crucial in its applications:

• Used extensively in jewelry for its durability.
• Valued in electronics for its superior conductivity and non-reactive nature.

This non-reactive quality ensures gold's longevity and luster, setting it apart from more reactive metals like silver.

Chemical Inertness

The concept of chemical inertness refers to the resistance a substance has to reacting with other substances. Metals like gold possess this characteristic due to their electron configuration:

• Inert materials resist oxidation and corrosion.
• This property makes them highly desirable in various industries.

Understanding chemical inertness helps explain why some metals, like gold, do not tarnish or corrode, unlike more reactive metals.

Noble Metals

Noble metals are a group of metals known for their corrosion resistance and high stability. This group commonly includes gold, silver, and platinum. They are:

• Highly resistant to oxidation and acids.
• Used in jewelry, electronics, and industrial applications.

These metals maintain their appearance and functionality over time, making them precious and valuable. Their chemical resilience stems from their electron configuration, allowing them to maintain stability in harsh environments.