chemistry of the environment Flashcards
describe the chemical test for the presence of water in anhydrous cobalt (II) chloride
Anhydrous ( no water ) cobalt(II) chloride, CoCl2, is blue
Hydrated cobalt (II) chloride, CoCl2*6H2O is pink
cobalt chloride paper changes from blue to pink the presence of water
describe the chemical test for the presence of water in anhydrous copper (II) sulfate
Anhydrous - ( no water) copper(II) sulfate, CuSO4 is white
Hydrated copper(II) sulfate, CuSO4*5H2O, is blue
anhydrous copper sulfate changes from white to blue in the presence of water
how to test for purity of water using melting and boiling point
water has a boiling point of 100 degree c and melting point of 0 degree c
impure water tends to boil above 100 degree celsius and impure water will melt at below 0 degree celsius.
what is distilled water and the difference between distilled water and tap water ?
water that is heated to form a vapour then condensed back into a liquid.
distilled water is used in practical chemistry as it has high purities, than tap water as tap water as high impurities that interfere with chemical reactions
what does water from natural resources contain
- dissolved oxygen
- metal compounds
- plastic
- sewage
- harmful microbes
- nitrates and fertilesers
- phosphates ( fertilizers & detergents )
what are the beneficial substances in water of natural resources ?
- dissolved oxygen for aquatic life
- some metal compounds providing minerals for life
what are harmful substances in water of natural resources ?
- toxic metal compounds
- plastics harmful for aquatic life
- sewage with microbes that causes disease
- nitrates and phosphates that lead to deoxygenation of life
describe the water treatment of domestic water
- sedimentation
- water is pumped through sedimentation tanks left for a few hours
- mud and other particles sink to the bottom forming a sediment layer
*water is filtered
-filtration of carbon ( charcoal ) - remove unpleased taste and odours
- chlorination
the removal of microorganism and bacteria that cause cholera and typhoid
what fertilisers are used
ammonium salts and nitrates are used as fertilisers
describe the use of NPK fertilizers
( nitrogen, phosphorus and potassium) to improve plant growth
- nitrogen makes chlorophyll & protein to improve health of leaves
- phosphorus promotes healthy roots
- potassium promotes growth and healthy fruits and flowers
what is the composition on clean dry air ?
- 78% nitrogen (N 2)
- 21% oxygen (O 2)
- remainder of noble gases - 0.9 % and carbon dioxide 00.4 % CO 2
What are the sources of air pollution ?
- carbon dioxide from the complete combustion of carbon fuels
- carbon monoxide and particulates from the incomplete combustion of carbon fuels
- methane from the decomposition of vegetation and waste gases from digestion in animals
- oxides of nitrogen from car engines
- sulfur dioxide from the combustion of fossil fuels which contain sulfur compounds
what’s are the effects of these air pollutants
- carbon dioxide and methane: higher levels of carbon dioxide leading to increases global warming leading to climate change
- carbon monoxide: toxic gas particulates: increased risk of respiratory problems and cancer
- oxides of nitrogen: photochemical smog and respiratory problems
- sulfur dioxide: acid rain
describe how green house gases carbon dioxide and methane cause global warming ?
Greenhouse gases like CO₂ and CH₄ trap heat in Earth’s atmosphere by absorbing and re-emitting infrared radiation, preventing thermal energy from escaping into space. This leads to increased global temperatures, contributing to global warming.
what are the strategies to reduce effects of these environmental issues ?
- climate change: planting trees, decreasing use of fossil fuels, increasing use of hydrogen and renewable energy, e.g. wind, solar
- acid rain: use of catalytic converters in vehicles, reducing emissions of sulfur dioxide by using low-sulfur fuels and flue gas desulfurisation with calcium oxide
what is photosynthesis?
a reaction between carbon dioxide and water to produce glucose and oxygen in the presence of chlorophyll and using energy from light
what is the word equation for photosynthesis
carbon dioxide + water = glucose + oxygen
Explain how oxides of nitrogen form in car engines and describe their removal by catalytic converters
In car engines, high temperatures (above 1000°C) cause nitrogen (N₂) and oxygen (O₂) from the air to react, forming oxides of nitrogen (NOₓ).
Cars use catalytic converters to reduce harmful emissions The converter contains platinum, palladium, or rhodium as catalysts.
It promotes reactions that convert harmful gases into less harmful substances, such as:2CO + 2NO → 2CO2 + N2
what is symbol equation for photosynthesis
6CO2 + 6H2O → C6H12O6 + 6O2
