air quality, climate and water
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what is the composition of clean dry air
78% nitrogen 21% oxygen and remainder is mixture of noble gases and carbon dioxide
name some air pollutants
carbo dioxide carbon monoxide particulates methane oxides of nitrogen sulfur dioxide
where does carbon dioxide come from + its effects
complete combustion of carbon containing fuels increased global warming leading to climate change
where does carbon monoxide and particulates come from + its effects
from incomplete combustion of carbon containg fuels toxic gas, poisonous and particulates cause increased risk of respiratory problems leading to cancer
where does methane come from + its effects
the decomposition of vegetation and waste gases from digestion in animals global warming leading to climate change
where does oxides of nitrogen come from + its effects
car engines acid rain, photochemical smog and respiratory problems
where does sulfur dioxide come from +its effects
from the combustion of fossil fuels which contain sulfur compounds acid rain
what are stratergies to reduce climate change
planting tress, reduction of livestock farming, decreasing use of fossil fuels, increasing use of hydrogen and renewable energy eg. wind, solar
what are stratergies to reduce acid rain
use of catalytic converters in vehicles, reducing emission of sulfur dioxide by using low-sulfur fuels and flue gas desulfurisation with calcium oxide
how do the greenhouse gases co2 and methane cause global warming
the absorption reflection and emission of thermal energy reducing thermal energy loss to space
how are oxides of nitrogen produced in car engines
in car engines where there is high temperature, nitrogen from air combines with oxygen in the air to produce NOx
how do catlytic converters work
harmful gases are absorbed onto surface of catlysts where they react to form harmless gases, catalysts speed up reaction A- harmful compounds are reduced eg. 2No -> N2 + O2 B- harmful compounds are oxidised using oxygen from A 2CO + O2 -> 2CO2 harmless product flows out exhaust pipe uses platinum or rhodium as catalyst onto ceramic honeycomb or ceramic beads
define photosynthesis
reaction between carbon dioxide and water to produce glucose and oxygen in the presence of chlorophyll and using energy from light
state word equation for photosynthesis
carbon dioxide + water -> glucose and oxygen
state symbol equation for photosynthesis
6CO2 + 6H2O -> C6H12O6 +6O2
What are 2 tests for the presence of water
anhydrous cobalt chloride turns blue to pink in presence of water anhydrous copper sulfate turns white to blue
how do you test for the purity of water
use melting/ freezing and boiling point if not 0 and 100 not pure
why is distilled water used in chemistry
because compared to tap water it contains fewer chemical impuraties
what are some substances that may be present in natural water
dissolved oxygen, metal compounds, plastics, sewage, harmful microbes, nitrates from fertilisers, phosphates from fertilisers and detergents
what are some beneficial substances found in water
dissolved oxygen for aquatic life and some metal compounds provide essential minerals for life
state some harmful substances in water and why they are harmful
some metal compounds are toxic, some plastics harm aquatic life, sewage contains harmful microbes that cause disease, nitrates and phosphates lead to deoxygenation of water and damage aquatic life
how is the treatment of domestic water supply
1- water pumped in, screen traps any big particles 2-a coagulant is added making small suspended particles stick together 3-air is blown through water in floatation tanks to make coagulated particles float to top where they are removed 4-water passed through bed of finde sand to filter 5-goes through carbon/ charcoal to remove tastes and odours 6-chlorine added to kill bacteria and other microbes