Problem 117 - Chemistry: An Atoms-Focused Approach

Question

Silver tarnish is the result of silver metal reacting with sulfur compounds, such as \(\mathrm{H}_{2} \mathrm{S},\) and \(\mathrm{O}_{2}\) in the air. The tarnish on silverware \(\left(\mathrm{Ag}_{2} \mathrm{S}\right)\) can be removed by soaking the silverware in a slightly basic solution of \(\mathrm{NaHCO}_{3}\) (baking soda) in a basin lined with aluminum foil. a. Write a balanced chemical equation for the tarnish formation reaction. b. Write a balanced net ionic equation for the tarnish removal process in which Ag_S S reacts with A1 metal, forming \(\mathrm{Al}(\mathrm{OH})_{3}(s), \mathrm{Ag}\) metal, and \(\mathrm{HS}^{-}\) ions.

Step-by-Step Solution

Answer

Question: Provide the balanced chemical equations for the formation and removal of silver tarnish. Answer: The balanced chemical equations for the formation and removal of silver tarnish are: Formation: 2Ag + H2S + O2 -> Ag2S Removal: 3Ag2S + 2Al -> 2Al(OH)3 + 6Ag + 3HS-

Step 1: Identify reactants and products

Silver metal reacts with sulfur compounds (H2S) and oxygen (O2) in the air to form silver tarnish (Ag2S). So, the reactants are Ag, H2S, and O2, while the product is Ag2S.

Step 2: Write the unbalanced equation

Write an equation representing the reaction using chemical symbols for the reactants and products: Ag + H2S + O2 -> Ag2S

Step 3: Balance the equation

In order to balance the equation, we need to ensure the number of atoms for each element on the reactant side equals the number of atoms for that element on the product side. For this equation, we can accomplish this by changing coefficients of the chemical compounds: 2Ag + H2S + O2 -> Ag2S Now, we have a balanced equation for the tarnish formation reaction. #b. Balancing the tarnish removal reaction#

Step 1: Identify reactants and products

In the tarnish removal process, silver tarnish (Ag2S) reacts with aluminum metal (Al) forming Al(OH)3(s), silver metal (Ag), and HS- ions. So, the reactants are Ag2S and Al, while the products are Al(OH)3, Ag, and HS-.

Step 2: Write the unbalanced equation

Write an equation representing the reaction using chemical symbols for the reactants and products: Ag2S + Al -> Al(OH)3 + Ag + HS-

Step 3: Balance the equation

In order to balance the equation, we need to ensure the number of atoms for each element on the reactant side equals the number of atoms for that element on the product side. For this equation, we can accomplish this by changing coefficients of the chemical compounds: 3Ag2S + 2Al -> 2Al(OH)3 + 6Ag + 3HS- Now, we have a balanced equation for the tarnish removal reaction.

Key Concepts

Silver Tarnish

Silver tarnish is that annoying black layer that forms on your beautiful silver jewelry or utensils. It happens due to a chemical reaction when silver (\(\text{Ag}\)) comes in contact with sulfur compounds, like hydrogen sulfide (\(\text{H}_2\text{S}\)) and oxygen (\(\text{O}_2\)) from the air.
Here's what happens:

• Silver reacts with the sulfur compounds.
• This leads to the formation of silver sulfide (\(\text{Ag}_2\text{S}\)), that dark, tarnishing layer.

Understanding this process helps us find ways to effectively remove tarnish without damaging the silver.

Balanced Chemical Equations

Balanced chemical equations are crucial in understanding chemical reactions. They ensure the law of conservation of mass is followed, meaning no atoms are lost or gained during the reaction.
For silver tarnishing:

• Unbalanced: \(\text{Ag} + \text{H}_2\text{S} + \text{O}_2 \rightarrow \text{Ag}_2\text{S}\)
• Balanced: \(2\text{Ag} + \text{H}_2\text{S} + \text{O}_2 \rightarrow \text{Ag}_2\text{S}\)

Balancing the equation ensures that each type of atom has the same number on both sides of the equation, keeping the chemical reaction accurate and predictable.

Net Ionic Equations

Net ionic equations simplify chemical reactions by focusing only on the ions that actually change during the reaction. This strips away the spectator ions that don’t really do anything.
In the tarnish removal process:

• The net ionic equation emphasizes the transformation of ions.
• It shows how aluminum (\(\text{Al}\)) interacts with silver sulfide, breaking it down to return silver to its shiny state.

This makes understanding the main chemical changes much clearer, helping students easily grasp complex reaction concepts.

Tarnish Removal Process

Removing tarnish involves using a bit of chemistry magic! An aluminum foil with baking soda solution creates a reaction that flips the tarnish back to silver.
Here's how:

• Place the tarnished silver in contact with aluminum foil in a baking soda solution.
• The \(\text{Ag}_2\text{S}\) reacts with \(\text{Al}\), forming \(\text{Al(OH)}_3\), silver, and \(\text{HS}^-\) ions.
• The balanced removal equation: \(3\text{Ag}_2\text{S} + 2\text{Al} \rightarrow 2\text{Al(OH)}_3 + 6\text{Ag} + 3\text{HS}^-\)

This process is a cost-effective method to restore shine, allowing the reduction of silver sulfide back to pure silver.