Silver

Silver is a chemical element and transitional metal, with the symbol Ag and atomic number 47. Silver has the highest electrical and thermal conductivity of any metal and is the most reflective metal.

Properties

Chemical

Silver is resistant to many acids, such as halogen acids and sulfuric acid, but will slowly dissolve in nitric acid forming silver nitrate, reaction sped up by heating. It's stable in pure air and water, but tarnishes when it is exposed to air or water containing ozone or hydrogen sulfide, in case of the latter it forms a black layer of silver sulfide which can be cleaned off with dilute hydrogen peroxide or hydrochloric acid. This phenomenon can be used as an indicator of air quality. Silver can be attacked by strong oxidizers, such as potassium dichromate or potassium permanganate, in the presence of potassium bromide.

Silver fulminate (AgCNO) is a powerful touch sensitive explosive, that has little value in chemistry because it's extremely sensitive to shock, heat, static electricity. It is however used in bang snaps.

Silver halides are photosensitive and are known for their ability to record a latent image, that can later be developed chemically, process that made photography possible.

Physical

Silver is soft, white metal. It has the highest electrical conductivity of any known metal and compound (except superconductors) and highest thermal conductivity.

Availability

Silver can be obtained from certain coins and jewelries. It is also found in many electric contacts as a sintered alloy, usually with nickel, copper and tungsten or tungsten carbide. There is no standard mixture, sometimes other elements are also present such as cadmium, which makes extraction difficult due to its toxicity. The specific gravity varies among the contacts, so determining the exact percentage of silver is difficult.

Silver can also be bought as ingots and bars, thought it's price will vary depending on the market.

Coin and button batteries(found on motherboards and in small electronics) often use silver oxide and zinc to generate power electrochemically. When these batteries are fully spent, the silver oxide inside has been reduced to silver metal, which can be carefully collected and purified. Another option is simply to dissolve the contents of the battery in nitric acid and precipitate the silver by adding copper, comparatively a much more reactive metal, to a solution of silver nitrate or another soluble silver salt.

Preparation

Silver can be obtained by reducing it's salt with a reducing agent, such as ascorbic acid.

Projects

• Silver nitrate
• Silver fulminate
• Silver aceltylide
• Silver azide
• Electrolytic silver cell
• Silver crystal growing, caused by insertion of a well-cleaned copper object such as wire into silver nitrate solution. The end product is a plant-like growth of silver crystals in a blue solution(copper(II) nitrate).

Handling

Safety

Silver metal has antiseptic properties and does not react with the organism. Silver compounds are harmful, and in large doses, silver compounds or colloids will deposit in various body tissues, leading to argyria, which results in a blue-grayish pigmentation of the skin.

Storage

Silver does not require special disposal, though if stored in sulfide polluted air, it will form a dark layer. The layer can be removed with hydrogen peroxide.

Disposal

Due to its high price, it's best to try to recycle the silver.