Chemical Fact Sheet
| Chemical Abstract Number (CAS #) | 7440-31-5 |
|---|---|
| Analytical Methods | 200.7 - 200.8 - 6010 - 6020 |
| Molecular Formula | Sn |
|
Synopsis
|
Tin-(anglo-Saxon, tin), Sn (L. stannum); at. wt. 118.710(7); at. no. 50; fp. 231.928 deg C; b.p. 2602 deg C; sp. gr. (gray) 5.75, (white)7.31; valence 2, 4. Known to the ancients. Tin is found chiefly in cassiterite (SnO2). Most of the world's supply comes from Malaysia, Bolivia, China, Indonesia, Russia, Zaire, Thailand, and Nigeria. The U.S. produces almost none, although occurrences have been found in Alaska and Colorado. Tin is obtained by reducing the ore with coal in a reverberatory furnace. Ordinary tin is composed of ten stable isotopes; thirty five unstable isotopes and isomers are also known. Ordinary tin is a silver-white metal, is malleable, somewhat ductile, and has a highly crystalline structure. Due to the breaking of these crystals, a "tin cry" is heard when a bar is bent. The element has two allotropic forms at normal pressure. On warming, gray, or alpha tin, with a cubic structure, changes at 13.2 deg C into white, or beta tin, the ordinary form of the metal. White tin has a tetragonal structure. When tin is cooled below 13.2 deg C, it changes slowly from white to gray. This change is affected by impurities such as aluminum and zinc, and can be prevented by small additions of antimony or bismuth. This change from the alpha to beta form is called the tin pest. There are few if any uses for gray tin. Tin takes a high polish and is used to coat other metals to prevent corrosion or other chemical action. Such tin plate over steel is used in the so-called tin can for preserving food. Alloys of tin are very important. Soft solder, type metal, fusible metal, pewter, bronze, bell metal, Babbitt metal, White metal, die casting alloy, and phosphor bronze are some of the important alloys using tin. Tin resists distilled sea and soft tap water, but is attacked by strong acids, alkalis, and acid salts. Oxygen in solution accelerates the attack. When heated in air, tin forms SnO2, which is feebly acid, forming stannate salts with basic oxides. The most important salt is the chloride (SnCl2 - H20), which is used as a reducing agent and as a mordant in calico printing. Tin salts sprayed onto glass are used to produce electrically conductive coatings. These have been used for panel lighting and for frost-free windshields. Most window glass is now made by floating molten glass on molten tin (float glass) to produce a flat surface (Pilkington process). Of recent interest is a crystalline tin-niobium alloy that is superconductive at very low temperatures. This promises to be important in the construction of superconductive magnets that generate enormous field strengths but use practically no power. Such magnets, made of tin-niobium wire, weigh but a few pounds and produce magnetic fields that, when started with a small battery, are comparable to that of a 100 ton electromagnet operated continuously with a large power supply. The small amount of tin found in canned foods is quite harmless. The agreed limit of tin content in U.S. foods is 300 mg/kg. The trialkyl and triaryl tin compounds are used as biocides and must be handled carefully. Over the past 25 years the price of commercial tin has varied from 50 cents/lb ($ 1.10/kg) to its present price of about $4.30/lb ($9.50/kg) as of January 1996. Tin with a purity of 99.9999% is available at a price of about $4/g. |
| Use | FOR BABBITT TYPE METALS. PRODUCTION OF TIN ALLOYS, LIKE SOLDERS, PHOSPHOR BRONZE, PEWTER, AND METAL TYPE BEARINGS. FOR CMPD AS OPACIFIERS FOR VITREOUS ENAMELS & AS REDUCING AGENTS IN CHEM PROCESSES. TINPLATE FOR STEEL CONTAINERS (EG, TIN CANS); BRASS ALLOYS; MANUFACTURE OF ORGANOTIN COMPOUNDS & INORGANIC TIN SALTS; TINNING, EG, TIN COATED COPPER WIRE; MISCELLANEOUS ALLOYS. Manufacture of collapsible tubes in the pharmaceutical and cosmetic industries; protective coating for other metals. *Corrosion resistant coatings, anodes for electrotin plating, hot dipped coatings, cladding, low melting alloys for fire control, organ pipes, dental amalgams, die casting. White, type, and casting metal. Manufacture of chemicals, tinned wire (all copper wire which is to be rubber covered). Block tin is used to coat copper cooking utensils and lead sheet, or to line lead pipe for distilled water, beer, carbonated beverages, and some chemicals. |
|
Consumption Patterns |
TINPLATE, 29%; SOLDER, 29%; BRONZE & BRASS, 14%; CHEMICALS, 8%; BABBITT, 4%; TINNING, 4%; ALLOYS (MISCELLANEOUS), 4%; MISCELLANEOUS, 8% (1979) [R1] Cans and containers, 18%; electrical, 20%; construction, 15%; transportation, 14%; and other, 33% (1986). |
| Apparent Color | CUBIC (GRAY); TETRAGONAL (WHITE); RHOMBOIDAL (TIN BRITTLE); HIGHLY CRYSTALLINE; ALMOST SILVER-WHITE, LUSTROUS SOFT, VERY MALLEABLE & DUCTILE METAL; ONLY SLIGHTLY TENACIOUS; EASILY POWDERED; WHEN BENT EMITS CRACKLING "TIN CRY"; BRITTLE @ 200 DEG C; BRINELL HARDNESS 2.9; AT -40 DEG C CRUMBLES TO GRAY AMORPHOUS POWDER (GRAY TIN); SLOWLY CHANGES BACK ABOVE 20 DEG C TO WHITE TIN |
| Boiling Point | 2507 DEG C |
| Melting Point | 231.9 DEG C |
| Molecular Weight | 118.69 |
| Density | 7.28 (white); 5.75 (gray); 6.52-56 (tin brittle) |
| Sensitivity Data | Tin dust is irritant to eyes & airways. Inorganic tin cmpd (except the oxides) irritate the skin. These compounds may cause irritation of nose, throat. Tin, stannous chloride, or stannic chloride can affect the body if they are inhaled or if they come in contact with eyes or skin. Inhalation of dust, eye & skin contact. |
|
Chemical and Physical Properties |
ATOMIC NUMBER 50 NATURALLY OCCURRING ISOTOPES: 112 (0.95%); 114 (0.65%); 115 (0.34%); 116 (14.24%); 117 (7.57%); 118 (24.01%); 119 (8.59%); 120 (32.97%); 122 (4.71%); 124 (5.98%) 2 OR 3 ALLOTROPIC FORMS; RESISTS DISTILLED, SEA & SOFT TAP WATER; OXYGEN IN SOLN ACCELERATES ATTACK; WHEN HEATED IN AIR, TIN OXIDE FORMS Heat of fusion: 1720 cal/g mole Specific Heat: 0.0510 cal/g/deg K @ 25 deg C (alpha); 0.0530 cal/g/deg K (beta) Thermal conductivity: 0.64 watts/cm deg C @ 25 deg C, 760 mm Hg Transformation temp: (beta in equilibrium with alpha) 13.2 deg C Specific heat: 222 J/kg K @ 20 deg C Latent heat of fusion: 7.08 kJ/(g atom) Thermal conductivity: 65 W/m K @ 20 deg C Coefficient of linear expansion: 19.9X10-6 @ 0 deg C; 23.8X10-6 @ 100 deg C Shrinkage on solidification: 2.8% Resistivity of white tin: 11.0 u-Ohm cm @ 0 deg C; 15.5 u-Ohm cm @ 100 deg C; 20.0 u-Ohm cm @ 200 deg C; 22.0 u-Ohm cm @ mp (solid); 45.0 u-Ohm cm @ mp (liquid) Volume conductivity: 15% IACS Tensile strength, as cast: 14.5 MPa @ 15 deg C; 4.5 Mpa @ 200 deg C; 20.0 MPa @ -40 deg C; 87.5 MPa @ -120 deg C |
|
Environmental Impact |
MOST OF OPERATIONS ASSOC WITH EXTRACTION & TREATMENT OF TIN ORE ARE WET PROCESSES, TIN DUST AND OXIDE FUME MAY ESCAPE DURING BAGGING OF CONCENTRATE, IN ORE ROOMS & DURING SMELTING OPERATIONS AS WELL AS DURING PERIODIC CLEANING OF BAG FILTERS USED TO REMOVE PARTICULATE MATTER FROM SMELTER FURNACE FLUE GAS. |
|
Environmental Fate |
TIN IS PRESENT UP TO 3 PPM IN THE EARTH'S CRUST & UP TO 3 PPB IN SEAWATER. FOUND IN CASSITERITE, STANNITE & TEALITE. OCCURRENCE IN EARTH'S CRUST: 6X10-4%. Present in meteorites, in natural waters, in soil. Mainly found in Malaysia, Indonesia, Chile, and Bolivia. Cotinental dust flux and volcanic emission release about 5000 tons into the atmosphere. Tin is concentrated in the nickel-iron core of the earth and appears in the highest concn in igneous rocks. |
|
Disposal |
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices. Chemical Treatability of tin; Concentration Process: Chemical precipitation; Chemical Classification: Metals; Scale of Study: Pilot scale; Type of Wastewater Used: Synthetic wastewater; Results of Study: At 600 ppm, 95.3% reduction with alum. At 500 ppm, 98% reduction with ferric chloride, 92% reduction with lime; (Three coagulants used: 200 mg of alum at pH= 6.4, 40 ppm of ferric chloride at pH = 6.2, 41 ppm of lime at pH= 11.5 Chemical coagulation was followed by dual media filtration). Recycling & landfill: Recovered particulates from an electrostatic precipitator can be recycled. The waste slag (inert and insol) may be buried in an approved landfill. Maximum concn of tin discharge to waterways is 2.0 ppm. Follow local regulations. |
 |
Alphabetical List of Compounds |
 |
List of Compounds by CAS Number |
 |
List of Services |
 |
Spectrum Laboratories Homepage |
