IB Chemistry Option E: environmental chemistry – Flashcards
Unlock all answers in this set
Unlock answersquestion
| Phosphate ions |
answer
| Weakly acidic soil |
question
| Nitrogen ions |
answer
| High ph |
question
| Calcium and magnesium |
answer
| Unavailable at high ph |
question
| Copper and zinc |
answer
| Intermediate ph |
question
| Aluminium and iron |
answer
| Low ph |
question
| Carbon monoxide |
answer
| Anthro: incomplete combustion of fossil fuels Natural: anaerobic decomposition of organic matter |
question
| Catalytic converter - how does it work? 3 equations |
answer
| Hot gases and air are passed over a platinum based catalyst. Gases are adsorbed onto surface of metal. Carbon monoxide, vocs, no 2CO O2 - 2CO2 CH - CO2 H2O NO 2CO - 2CO2 N2 |
question
| Nitrogen: source and control |
answer
| Anthro: combination of nitrogen and oxygen in internal combustion engine at high temperatures. Natural: lighting storms Control: catalytic convertors with high fuel to low air ratio. |
question
| Volatile organic compounds |
answer
| Organic compounds...duh Anthro: unburned petroleum. Hydrocarbons from petrol. Solvents. Natural: decomposition of organic matter in soil. Control: catalytic convertors |
question
| Sulfur oxides |
answer
| Anthro: combustion of coal containing Sulfur in factories Natural: volcanic activity and oxidation of h2s in decay of organic matter Control: remove Sulfur from fossil fuels. Alkaline scrubbing Fluidized bed composition |
question
| Alkaline scrubbing |
answer
| Alkaline mixture (calcium Oxide or calcium carbonate) sprayed into exhaust gases. Forms calcium Sulfate - deposited in landfill or used to make plasterboard. |
question
| Fluidized combustion method |
answer
| Coal mixed with powdered limestone on metal plate. Air flow carries limestone and particles over plate. Heat from combustion of coal causes calcium carbonate to break into cao and co2. Calcium oxide reacts with Sulfur to produce calcium Sulfate l |
question
| Electrostatic precipitation |
answer
| Gas is ionised Electrons collect on particulates Particulates are Attracted to positive collector plates. Collector plates are shaken |
question
| Particulates |
answer
| Anthro: spot( incomplete combustion of hydrocarbons) Natural: dust from beak up of matter. Sulfur from Volcanic eruptions. Control: electrostatic precipitation. |
question
| Acid deposition |
answer
| Process by which acidic particles, gases and precipitation leave the atmosphere. |
question
| Origins of acid deposition |
answer
| S O2 - SO2 SO2 H20 - H2SO3 2SO2 O2 - 2SO3 SO3 H20 - H2SO4 N2 O2 - 2NO 2NO2 H2O - H2NO3 HNO2 |
question
| Environmental effects of acid deposition. Methods to counteract. |
answer
| Erodes statues and buildings of calcium carbonate, Increases rate of rusting. Washes nutrients from soil. Releases al3 . Stunted growth and leaf loss Fish cannot survive in acidic conditions - al3 ions dissolve and reduced ability to take oxygen. HNO2 and HNO3 = eutrophication |
question
| Greenhouse effect |
answer
| Warming of the earth caused by infrared radiation, emitted by the earth's surface- absorbed by various gases in earth's atmosphere responsible are water vapour, CH4, CO2, nitrous oxide |
question
| List main greenhouse gases and discuss their relative effects. |
answer
| CO2 - combustion of fossil fuels H2O - evap of water and lakes CH4 - anaerobic decomposition. |
question
| Primary pollutants of photochemical smog and sources |
answer
| Nitrogen monoxide - NO= internal combustion engine - at HIGH temperatures. VOC's - car exhausts |
question
| Name secondary pollutants in photochemical smog |
answer
| Nitrogen dioxide - NO2 Ozone Aldehydes Nitric acid PANs |
question
| Conditions necessary for smog to occur. |
answer
| Bowl shaped cities cause thermal inversions. Thermal inversion traps pollutants - which collect over city. Vocs and NOx in atmosphere |
question
| How are secondary pollutants formed in smog? |
answer
| 2NO O2 - 2NO2 SUNLIGHT is essential to sub reactions! NO2 - NO O• O2 O• - O3 Peroxy radicals: CH3C(O)OO• NO2 ~ CH3C(O)OONO2 |
question
| Description of formation and depletion of ozone. |
answer
| F:O2 UV = 2O• O• O2 = O3 D: O3 UV = O2 O• O3 O• = 2O2 |
question
| List ozone depleting substances and their sources |
answer
| NO• and NO2 - internal combustion engine - jet aircraft. Chlorofluorocarbons CFCs aerosols, refrigerants, solvents, foaming agents, plastics |
question
| Discuss alternatives to CFCs inc. toxicity, flammability, relative weakness of C-Cl bond and ability to absorb infrared radiation. |
answer
| Hydrocarbons: flammables and highly toxic, C-H stronger than C-Cl bond. Fluorocarbons: not flammable, no know toxic effects, C-F bond very strong compares to C-Cl. Hydrofluorocarbons: not flammable, low toxicity, C-F stronger |
question
| Define biological oxygen demand |
answer
| Quantity of oxygen needed to oxidise organic matter in a sample of water over five day period at a specific temperature. |
question
| Distinguish between aerobic and anaerobic decomposition of organic material in water. |
answer
| Aerobic decomp = organic material is oxidised Anaerobic decomposition = material is reduced |
question
| Describe the process of eutrophication and its effects. |
answer
| BOD increases because addition of extra nutrients (phosphates and nitrates). Excess nutrients promotes algae and plant growth as nitrates used in protein synthesis. Excess of nutrients known as eutrophication. Limites oxygen = Algae death = decay increase no of nutrients. Not enough oxygen for aerobic decomposition = Anaerobic decomposition. |
question
| Thermal pollution |
answer
| Water used as cooling agent. Concentration of dissolved oxygen decreases with rising temperatures. Oxygen insufficient for fish to survive - fertilisation etc sensitive to temp |
question
| List primary pollutants in waste Water and identity sources. |
answer
| Heavy metals - paints, batteries, lead pipes Pesticides - insecticides etc Dioxins - added to organochloro compounds when incinerated. Weed killers. Polychlorinated biphenyls: electrical transformers Organic matter : artificial Fertiliser (phosphate and nitrate ions) |
question
| Primary waste water treatment |
answer
| Filtration: screens and grids filter large insoluble solids Sedimentation tank: allowed to settle - sludge is removed from bottom of tank. |
question
| Secondary treatment of waste water. |
answer
| Activated sludge process: air enriched with oxygen AND bacteria bubbled through waste war. BACTERIA oxidises organic matter. Passe through sedimentation tank - settle and removed. 80% removed. |
question
| Tertiary treatment of waste water |
answer
| Heavy metal ions: removed by bubbling through carefully controlled amounts of H2S. Removed by filtration - excess H2S removed because acidic. Phosphates: addition of calcium and aluminium ions. Nitrates biological methods anaerobic organisms turn NO3- to N2. |
question
| Multi- stage distillation |
answer
| Sea water TO fresh water. sea water is heated - passed into evacuation chamber - boils - leaves dissolved compounds - steam passes through condenser. Cooled by pipes contains sea water. Sea water in pipes become slightly warm. |
question
| Reverse osmosis |
answer
| Sea water TO fresh water Partially permeable membrane that can withstand high temperatures. Increase pressure so moves from High concentration to low concentration.eaves dissolved salts behind. |
question
| Salinisation |
answer
| Cause of soil degradation. Irrigation water contains salts. Soil is continuously irrigated - salts are deposited. poorly drained soils = salts begin to Accumulate in topsoil. Excess salt = plants cannot grow |
question
| Soil degradation |
answer
| Human activity reduces the capacity of soil to support life. |
question
| Nutrient depletion |
answer
| Cause of soil degradation. When plant dies - nutrients and minerals returned to soil. Crops are harvested = nutrients removed from soil. |
question
| Soil pollution |
answer
| Cause of soil degradation. Mining / excess use of agricultural fertilisers - pesticides- Improper disposal of toxic waste. Polluted soil - contaminated plants - contaminated food chain. Run into surface waters - polluting groundwater. |
question
| Soil organic matter |
answer
| Represents organic constituents in soil, inc undecayed plant and animal tissues, their partial decomp and soil biomass. High molecular- proteins polysaccharide Simpler - sugars, amino acids |
question
| Physical functions of SOM |
answer
| Structural stability- organic matter loosens soil increasing amount of pore space. Soil structure improves. Influences water retention- more porous therefore hold More water and air. Black - absorbs heat and helps to warm in spring |
question
| Biological |
answer
| Source of nutrients. Resilience of soil and plant system. |
question
| List common organic soil pollutants and sources |
answer
| Petroleum hydrocarbons - unburnt petroleum. Agrichemicals - pesticides weed killer insecticides VOCs - terpenes, solvents , unburnt petroleum, anaerobic decom organic matter PAHs |
question
| Benefits of recycling |
answer
| Reduces use of raw materials. Energy costs Level of pollutants. Need of land for Waste disposal |
question
| Characteristics and sources of low level radioactive waste |
answer
| Clothing, paper towels in hospitals. fuel Containers, smoke alarms Activity is low , short half life , high volume. |
question
| High level radioactive waste |
answer
| Nuclear industry : spent fuels rods. High activity, long half life, low volume. |
question
| Storage and disposal of diff types of radioactive waste. |
answer
| Low level waste: stored in cooling ponds of water until activity falls to safe levels. Ions from water responsible for activity removed. - diluted and released into sea. Steel containers - concrete lined vaults. High level: buried deep underground. Land masses may move. Potential weapon terrorist. Leak into water supply. |
question
| Outline dependence of O2 and O3 on wavelength of bond. |
answer
| O2 has stronger bonds than O3 therefore O2 needs high energy, short wavelength 242= UV O3 uv of lower energy. 330nm |
question
| Describe catalysis of O2 by CFCs and NOx |
answer
| CCl2F2 - CClF2 Cl• Cl• O3 - ClO• O2 ClO• O• - O2 Cl• NO O3 - NO2 O2 NO2 O• - NO O2 CATALYSTS - Not used in reactio. |
question
| Outline reasons for greater ozone depletion in polar regions |
answer
| Very cold. Clouds of ice form. Ice become heterogenous catalysts - provide surface for reactants. |
question
| Explain role of ammonia in acid deposition. |
answer
| Ammonia neutralises acid in atmosphere - forming ammonium salts. Slightly acidic ammonium salts (NH4)2SO4 and NH4NO3 sink to ground or washed out of atmosphere by rain. NH4 deposits on soil = nitricification and acidification. |
question
| Common ion effect |
answer
| Increase in concentration of ions = decrease in solubility of ions. |
question
| Why is it difficult to remove nitrate ions by chemical means? |
answer
| Nitrate ions are soluble in water |
question
| Name two methods by which you can remove nitrate ions from water? |
answer
| Biological: anaerobic organisms can turn nitrogen in nitrates to atmospheric nitrogen. Algae ponds. Ion Exchange: |
question
| Ozone depleting equations |
answer
| O3 NO ~ O2 NO2 NO2 O• ~ NO O2 |
question
| Chemical equation for formation of a PAN |
answer
| CH3C(O)OO• NO2 ~ CH3C(O)OONO2 H removed removed from aldehyde (free radical which needs sunlight)- and then reacted with No2 |
question
| Effects of enhanced greenhouse effect |
answer
| Melting glaciersof - expansion of oceans = flooding. Drought/ increased rainfall - change crop yields. Changes biodiversity. |
question
| Desrcibe Thermal inversion |
answer
| Traps polluted air closer to ground by - increase in altitude causing increase in temp. |
question
| Advantage of landfill |
answer
| Low cost. Filled ground can be reused. |
question
| State what is mean by cation exchange capacity |
answer
| Amount of exchangeable cations in clay. |
question
| Explain why CEC depends on pH. |
answer
| H ions displace exchangeable cations from soil. Reduces nutrients from the soil/ leached from soil |
