CHEMICAL SAFETY IN SCHOOLS/COLLEGES – REDUCING RISKS TO YOUNG PEOPLES Dr. M.K.N. Yenkie Professor of Chemistry Registrar – RTM Nagpur University Director - Laxminarayan Institute of Technology R.T.M. Nagpur University Nagpur - 440 033
Periodic Table of the Elements Elements are arranged by atomic number Elements in the same vertical columns have similar properties “Halogens” “Alkali Metals” 2
CHEMICALS • Chemicals have invaded all sectors of human life • Possess inherent dangers Chemistry has the potential to solve the mysteries of life. However, NO CHEMICAL IS TOTALLY SAFE OR NON HAZARDOUS ONLY SAFE WAY OF HANDLING THEM
Dangers associated with chemicals • Storing raw material • Production site • Storing products • Transport
Lab Chemicals • Acids and Bases • Permanganate • Salts • Burners • H2S
Chemicals used at Home • Acids and Bases • Permanganate • Salts • Burners • Bleaching powder • Insecticides • Protection of grains
Ammonia Anhydrous Ammonia pH>12; (household ammonia pH < 12) Wide industrial use Plastics, fertilizer, explosives Irritating, corrosive; causes necrosis, severe pain Serious injury to eyes, lungs, skin, GI tract Management Remove from exposure, decontaminate Symptomatic; maintain airway
Ammonia • Chemical Formula: NH3 CAS# 7664-41-7 UN#1005 ISCS: 0414 • Physical State: Colorless , compressed liquefied gas, with pungent odor • Physical Properties • Boiling Point: -33°C • Relative Density: 0.7 at -33°C • Vapor Density: 0.59 • Solubility in water 54 g/100mL, 20°C • Vapor Pressure, 1013 kPa at 26°C • Explosive Limits, vol% in air: 15-28 • Auto-ignition temperature: 651°C Fire and Explosion: Flammable; gas/air mixtures are explosive. Health Hazards Corrosive to eyes, skin, respiratory tract. Inhalation results in burning sensation, labored breathing; skin burns; contact with liquid causes frostbite; severe deep burns to eyes; harmful concentration of this gas in air will be reached very quickly on loss of containment Route of Exposure: Inhalation Chemical Dangers: Shock sensitive compounds are formed with mercury, silver and gold oxides. The substance is a strong base; it reacts violently with acid and is corrosive. Reacts violently with strong oxidants and halogens. Attacks copper, aluminum, zinc and their alloys. Dissolves in water evolving heat. Physical Dangers: The gas is lighter than air. Use: Manufacture of nitric acid, explosives, synthetic fibers, and fertilizers. 8
Class 1 Explosives Class 2 Compressed Gases Class 3 Flammable Liquids Class 4 Flammable Solids Class 5 Oxidizers Class 6 Poisons Class 7 Radiological Class 8 Corrosives Class 9 Other Regulated Materials UN Classification Hazard Classes and Divisions
Class 1 – Explosives Mass explosion that affects almost the entire load
Class 2 – Gases POISON GAS NON-FLAMMABLEGAS 2 FLAMMABLE GAS 2 2
Class 3 – Flammable Liquids FLAMMABLE 3
Class 4.1 – Flammable Solids Flammable Solid 4
Class 4.2 – Spontaneously CombustibleMaterials SPONTANEOUSLY COMBUSTIBLE 4
Class 4.3 – Dangerous When Wet Dangerous when Wet 4
Class 5.1 – Oxidizers Oxidizer 5.1
Class 5.2 – Organic Peroxides Organic Peroxide 5.2
Class 6.1 – Poison, Inhalation Hazard Poison 6.1
Class 7 – Radioactive Radioactive
Class 8 – Corrosive Corrosive
Class 9 - Miscellaneous Hazardous Materials Or Other Regulated Materials(ORM)
Aerosol / Infectivity Relationship Particle Size (Micron, Mass Median Diameter) Infection Severity The ideal aerosol contains a homogeneous population of 2 or 3 micron particulates that contain one or more viable organisms Less Severe More Severe 18-20 15-18 7-12 4-6 (bronchioles) 1-5 (alveoli) Maximum human respiratory infection is a particle that falls within the 1 to 5 micron size
Lake Nyos was formed due to volcanic eruption about 400 years ago. It is 5,900 feet across and 682 feet deep. Lake Nyos is compositionally stratified with layers that do not mix, with fresh water in the upper 50 meters and heavier sodium and carbon dioxide (CO2) rich water below that. It is one of only three known lakes to be saturated with CO2 in this way. Approximately 50 miles below the lake resides a pool of magma, which charges the water of Lake Nyos with an estimated 90 million tons of CO2. The lake waters are held in place by a natural dam composed of volcanic rock.
Disaster Strikes At 9:30 pm on August 21, 1986 - eruption Lake Nyos triggered sudden release of 1.6 million tons of CO2.. The cloud of CO2 rose at nearly 62 miles per hour. Carbon dioxide, 1.5 times as dense as air, cloud hug the ground and descend down the valley. The 164 ft thick cloud traveled downward at a rate of 12-31 mph. killed over 1700 people, thousands of cattle, birds and animals. The bodies of those that died were generally devoid of trauma, suddenly fallen asleep and died from asphyxiation. Following the disaster, the lake was dubbed the “Deadliest Lake” by the Guinness World Records in 2008.
The Science Behind the Disaster It is important to remember that Lake Nyos is thermally stratified- with layers of warm, less dense water near the surface floating on the colder, denser waters near the lake’s bottom. Over time, the lowest levels of the lake become more and more saturated with gas. And eventually, when they reach 100% saturation, the CO2 rich gas can bubble spontaneously out of the lake , creating a foaming column of carbonated water. This eruption can be triggered by an event such as a landslide, earthquake, violent storm, or other disturbance of the water. The normal blue waters of the lake turned a deep red after the outgassing, due to iron-rich water from the deep rising to the surface and becoming oxidized by the air. The level of the lake dropped about a meter, representing the volume of gas released
-Sn “grey tin” -Sn “white tin” -Sn Sn(l) 13.2°C 161°C 232°C Tin: allotropic forms: -Sn: typical metallic properties: conductor, ductile crystal structure: body centered tetragonal d = 7.29 g/cm3 -Sn : semiconductor, non-ductile crystal structure: diamond cubic d = 5.77 g/cm3
Tin Pest(tin disease, tin plague, devil´s disease): first reported: 1851; responsible for the disintegration of tin dishes, organ pipes, … is the product of the conversion: -Sn -Sn at T < 13.2 °C volume change leads to the total disintegration of the sample
Tin Pest without tin pest complete disintegrated
All for want of a button Tin has two allotropic forms : α (gray tin ) β (white tin) White tin is shiny metal and stable at room temperature but slowly transforms into gray tin below 13 oC. This weakens the metal and makes it crumble (tin disease). In June 1812, Napoleon’s mighty army, some 600,000 strong marched into Russia, but by early December his forces were reduced to fewer than 10,000 men. An intriguing theory for Napoleon’s defeat has to do with tin buttons on his soldiers’ coats! The soldiers were probably more busy holding their coats together with their hands than carrying weapons.
Mars Surveyor Program 1999 Mars Climate Orbiter Mars Polar Lander
Mars Surveyor Program 1999 (Orbiter and Lander) Mission: To study Martian weather, climate, atmosphere, evidence of life, … $327.6 million total MCO lost due to navigation error Launch Dec 11, 1998 – Lost Sep 23, 1999 Failure is attributed to the failure of NASA’s system engineering process. The process did not specify the system of measurements to be used in the project (English vs. Metric) MPL never called home! Launch Jan 3, 1999 – Lost: Dec 3, 1999
Mars Surveyor Program 1999 (Orbiter and Lander) In December 1998 NASA launched the 125 Million$ Mars climate Orbiter. After 416 Million mile jorney, the space craft was supposed to go into Mars’ orbit on Sept. 23, 1999. Instead it entered Mars’ atmosphere about 100 km (62 Mile) lower than planned and was destroyed by heat. The error occurred due to the failure to convert English Measurement units into metric unit. Engineers at Lockheed Martin Corporation who built the spacecraft specified its thrust in pounds. Scientists at NASA,s Jet Propulsion Laboratory, on the other hand assumed that thrust data they received were in metric units, as Newton.
Conversion between Pound and Newton 1 Pound is the force due to gravitational attraction on an object of that mass. 1 lb = 0.4536 kg, from Newton’s second law : force = mass x accelaration = 0.4536 kg x 9.81 m/s2 = 4.45 kg. m/s2 = 4.45 N Because 1 N = 1 kg m/s2, instead of converting one pound of force to 4.45 N, the scientists treated it as 1 N. this considerable small thrust resulted in a lower orbit and the ultimate destruction of the spacecraft.
The Patriot Missile Failure February 25, 1991 – Gulf War – Dharan, Saudi Arabia American Patriot Missile battery failed to track and intercept an incoming Iraqi Scud missile 28 US soldiers killed, 100+ injured Software bug: inaccurate calculation of the time since boot due to computer arithmetic errors
Minamata, Japan Mercury Poisoning Disaster The Minamata Disaster was more of an on going mass poisoning than a single catastrophe. It was caused by the Chisso Corparation in the city of Minamata on Kyushu Island, Japan. They dumped organic mercury off the coast of Minamata for over 3 decades. There have been over 3,000 victims. Many of them lost their lives and others suffered from physical deformities.
Bioaccumulation occurs when an organism takes up contaminants more quickly that it eliminates them Biomagnification is an incremental increase in the concentration of a contaminant at each level of the food chain http://wi.water.usgs.gov/pubs/FS-216-95/mercury.pg2.pdf
Disaster Continued Chisso knew the mercury they were dumping was contaminating the water, but did nothing. The poisoned waters created a ripple effect; killing marine life, birds, domestic animals and humans. Villagers that complained were measly compensated or threatened. The Chisso Corporation stopped poisoning the waters in 1968 only when the method of mercury production became outdated.
Signs and Symptoms Victims were diagnosed with a degenerative nerve condition. Signs included: Numbness of the limbs and lips Slurred speech and blurred vision Brain damage Loss of consciousness Involuntary movements Symptoms of Turrets Syndrome (uncontrolled shouting) Physical Deformities
BHOPAL DISASTER Total breakdown of essential safety provisions and negligence of the authorities According to safety norms MIC tanks should be protected by dry Nitrogen blanket and kept at 0 oC by refrigeration. Refrigeration unit was shut down since June 1984, gas was at 15-20 oC. MIC reacts violently with water and also undergoes polumerisation in presence of catalysts like Fe, Cu, Zn (both processes highly exothermic) MIC is always associated with 2% Phosgene (TLV 0.1 ppm) Leakage detected at 11.30 p.m., Temperature gauge showed 25 oC, pressure build up above 55 psi and the safety valve opened. MIC gushed out from 120 ft. high stack, water jet failed to reach that height, vent gas scrubber which neutralizes MIC with caustic soda was out of order. Factory turned on the public siren at 1 am for a few minutes only, people got up not due to siren but due to irritation caused by gas. For about two hours the safety valve remained open and then reseated as the tank pressure dropped below 40 psi.