Silver Mirror - Periodic Table of Videos

TL;DR

Chemistry is used to create a vacuum inside a thermos flask, and silvering the glass helps reflect heat back in.

Transcript

we regularly in chemistry we use thermos flasks you know like like you keep for coffee or soup um and we use thermos flasks to keep things cold and what we thought we'd show you today is how some chemistry of one of the elements is used to make a thermos flask so Neil is taking one apart what we can see here is the inside of a thermos flask so this... Read More

Key Insights

• 😎 Thermos flasks rely on a vacuum and silvered glass to maintain the temperature of the contents.
• 🥈 Silver nitrate is used as the starting material for silvering glass.
• 🥈 The reaction between silver nitrate and ammonia produces silver hydroxide.
• 🥺 Further reaction with ammonia and reduction using a sugar solution leads to the formation of metallic silver.
• 🥈 The metallic silver is precipitated on the inside of the flask, creating a mirror-like coating.
• 💦 Washing the flask with water is important to remove any excess solution and stabilize the mirror coating.
• 😎 The chemistry behind silvering glass is a delicate equilibrium reaction that occurs quickly.

Questions & Answers

Q: How is a vacuum created inside a thermos flask?

A vacuum inside a thermos flask is created by removing all the atmosphere using a pump. This helps maintain the temperature of the contents by minimizing heat transfer through conduction or convection.

Q: Why is the inside of a thermos flask silvered?

The inside of a thermos flask is silvered to reflect heat back in. The silver coating helps minimize heat loss through radiation, keeping the contents at the desired temperature for a longer duration.

Q: What is the starting material for silvering glass?

The starting material for silvering glass is silver nitrate. It is dissolved in deionized water to create a salt solution that is further reacted to produce silver hydroxide.

Q: How is the silver hydroxide reduced to create metallic silver?

The silver hydroxide is reduced by adding more ammonia to displace the hydroxide ions. This reaction results in the formation of a silver diamine compound, which is then converted to metallic silver by adding a sugar solution.

Summary & Key Takeaways

• Thermos flasks use a glass envelope with a vacuum inside and a silvered inside layer to reflect heat back in.

• Silver nitrate is dissolved in deionized water to create a salt solution, which is then reacted with ammonia to create silver hydroxide.

• The silver hydroxide is further reacted with more ammonia and reduced using a sugar solution to create metallic silver.

• The metallic silver is then precipitated on the inside of the flask, creating a reflective mirror-like coating.