This Is a True Story; Can You Explain What Happened

question 102

Multiple Choice

This is a true story; can you explain what happened? Prior to a really important dinner party, the hostess discovered that her silverware was very tarnished. She needed a quick fix. She remembered reading that the tarnish (Ag₂S) would be removed if you immersed the silverware in a hot solution of backing soda (NaHCO₃) in a pan lined with aluminum foil. So she did, and so it was, but she noticed a bit of a rotten egg smell (H₂S) being produced. Metal/Metal ion
E silver/silver(I) 0.799
Aluminum/aluminum(III) -1.677

• A) Aluminum ions react with S^2-, form an aluminum sulfide precipitate, and gaseous carbon dioxide is released.
• B) Silver ions in the presence of the baking soda, (NaHCO₃), oxidize the sulfide to elemental sulfur that attacks the aluminum foil, which produces the smelly aluminum sulfide.
• C) The aluminum acts as a reducing agent for the silver(
• I) in the silver sulfide; then the bicarbonate ion protonates the sulfide ion that is released.
• D) Aluminum is plated onto the silver surface, making it shiny again, and then the reaction of the bicarbonate with the aluminum oxide releases CO₂.
• E) Silver in Ag₂S reduces the aluminum, becomes metallic silver in the process, and releases hydrogen sulfide, H₂S.

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Definitions:

LIFO Periodic

An inventory valuation method, Last In First Out, used in periodic inventory systems where the last items added to the inventory are assumed to be sold first.

Perpetual LIFO

Perpetual LIFO, or Last-In, First-Out, is an inventory accounting method continuously updating inventory and costs of goods sold by assuming the last items purchased are the first to be sold.

Ending Inventory

The worth of products ready for purchase at the conclusion of a financial period.