Chemistry section 12 Flashcards
(37 cards)
what is a sulhydryl group?
-SH, metals have a high affinity for heavy metals
what is speciation?
the chemical form of the element
why has there been a recent decline in emissions of Hg?
- Emissions controls on waste incinerators
- remove batteries and paint from waste stream
- controls on metal smelting
- closure of chlor-alkali plants
Is liquid or vapour mercury more toxic?
Vapour - neutral charge which allows the hg to pass through membranes
what is an amalgam?
solutions or alloys which combine mercury with one or many metals - Dental
How does chlor-alkali process release mercury to env?
the cooling water for the plant is recycled back into the system which it came from leading to contamination of the system
2 uses for Hg in batteries
- prevents erosion of zinc cathode
2. used to prevent the release and build up of hydrogen gas
Sources of environmental mercury? 4
- unregulated burning of coal
- incineration of municipal/medical waste
- metal and steel industries
- gold and other non-ferrous metal production
3 Hg forms emitted from a coal power plant?
- GEM Hg^naught
- Particulate Hg - Hg ^2+
- RGM - HgCl2
Formula for methylmercury and common forms ?
CH3Hg
- CH3HgCl
- CH3HgOH
sources of dietary Hg in humans?
- Fish
2. rice grown in areas of china near factories
what is the minamata disease?
Hg into water where factory dumped waste -> into fish supply and then into humans… fucks with nervous system
How can lead in ammunition be a danger to wild life?
Birds eat lead shot, birds of prey eat animals shot with lead shot, condors in cali eat deer which has been shot
What are the two common forms of lead?
Pb2+
Pb4+
How can lead dissolve into a can of fruit even though it is insoluble in mineral acids?
The air oxidizes the Pb(s) to Pb(aq)
Why is lead pipe water contamination less common in areas with hard water?
An insoluble layer of PbCO3 forms on the surface of the lead preventing it from dissolving
Why is lead used in paints?
it gives stable brilliant colours (Red, yellow, white) and prevents mold and mildew
why are heavy metal compounds more soluble in acidic water?
in the case of PbS, the sulfide ion is converted to HS and then to H2S which leaves the Pb2+ in the wata
what form of lead is in lead storage batteries?
Pb2+, Pb 4+, PbO2
2 organic lead compound used in gasoline?
- Tetramethyllead -Pb(CH3)4
- Tetraethyllead
Used to reduce knocking, both volatile and entered the environment
Toxicity of lead in terms of reproduction and intelligence
- Neuropsychological impairment and reduced iQ
- Fucks with the fetus brain
Who is at a higher risk from lead contamination
- the young
2. those with iron/calcium deficiency
What are the main sources of cadmium in the env?
- byproduct of zinc smelting
2. lead and copper smelters
What is the main source of cadmium in humans?
Food supply - seafood and organ meats and grains potatoes
