C10 - chemistry of the environment

Question 1

define groudnwater

Answer 1

water from underground

Question 2

define aquifer

Answer 2

water from underground

Question 3

water tests (reversible reaction)

Answer 3

1) anhydrous Copper (II) sulfate + water ⇌ hydrated Copper (II) sulfate
white ⇌ blue
A CS major W suck- A Comp Sci major Will suck.
2) anhydrous Cobalt (II) chloride + water ⇌ hydrated Cobalt (II) chloride
blue ⇌ pink

Question 4

process of treatment of water

Answer 4

-screen the big items
-add coagulant; make soluble things insoluble (ppt & form sediment)
-filter sediment with sand
-add carbon; remove taste & smell
-add chlorine; kill pathogen & microbes
-add fluorine; prevents teeth enamel from decaying
-store water in reservoir

Question 5

why may some water be harmful even after treatment

Answer 5

-mosquito lays eggs
-algae grows

Question 6

how to make dirty water safe for drinking

Answer 6

-boil it
-filter it

Question 7

how to get pure water from seawater

Answer 7

simple distillation

Question 8

how to check if water is impure

Answer 8

-melt below 0C
-boils above 100C

Question 9

air percentages

Answer 9

78% - nitrogen
21% - oxygen
1% - other gases (argon, carbon dioxide, water vapor, noble gases)

Question 10

things needed for combustion

Answer 10

-fuel
-heat
-oxygen

Question 11

uses of nitrogen

Answer 11

-liquid N2 freezes food for transport - low reactivity & abundant supply
-fertiliser

Question 12

uses of oxygen

Answer 12

-aerobic respiration
-welding in gas tanks
-fuel cell

Question 13

uses of noble gases

Answer 13

-coloured lights (argon, neon, helium)
-fire extinguisher (argon)
-advertising signs
-balloons

Question 14

most reactive gas in air

Answer 14

-oxygen
-nitrogen & noble gases aren’t that reactive

Question 15

how to separate gases in air

Answer 15

-pump air
-remove carbon dioxide & water vapor
-expand & compress gas to liquify it at -200C
-boil liquid & elements gases rises in order of lowest boiling point (fractional distillation)

Question 16

order of gases rising in air separation

Answer 16

nitrogen, argon, oxygen, krypton, xenon

Question 17

biggest expense when separating air

Answer 17

electricity to run for compression & expansion

Question 18

experiment to measure % of oxygen in air

Answer 18

-100cm^3 of air in gas syringe
-copper in between gas syringe and another glass
-heat copper as syringe pumps air back & forth
-oxygen is used up to make Copper oxide which changes from brown to black = reaction is complete
-79% air left

Question 19

how to reverse reaction in experiment to measure % of oxygen in air using

Answer 19

-fill syringe with helium
-copper is displaced from Copper oxide

Question 20

common pollutant in the air

Answer 20

-carbon particles
-sulfur dioxide
-nitrogen monoxide
-nitrogen dioxide
-carbon monoxide
-carbon dioxide
(methane)

Question 21

harmful effects of sulfur dioxide

Answer 21

-causes acid rain (react with water vapor in cloud & form sulfuric acid) = acidic soil, kills animals, corrode buildings

Question 22

harmful effects of nitrogen oxides

Answer 22

-causes acid rain (react with water vapor in cloud & form nitric acid) = acidic soil, kills animals
-respiratory problems
-nitrogen dioxide = photochemical smog = global dimming (no photosynthesis, warmth, vitamin D)

Question 23

harmful effects of carbon dioxide

Answer 23

-increases global warming = climate change = extreme weather conditions, less thermal energy loss to space

Question 24

harmful effects of carbon monoxide

Answer 24

-toxic gas to humans (binds to hemoglobin)

Question 25

harmful effects of methane

Answer 25

-increases global warming = climate change = extreme weather conditions, less thermal energy loss to space

Question 26

harmful effects of carbon particles

Answer 26

-respiratory problems -cancer risk

Question 27

how is sulfur dioxide formed

Answer 27

-combustion of fossil fuels which contain sulfur compounds -volcanos

Question 28

how is nitrogen oxides formed

Answer 28

-made in air from complete & incomplete combustion of nitrogen from high temp & pressure in car combustion engines

Question 29

how is carbon oxides formed

Answer 29

-complete & incomplete combustion of fossil fuels containing carbon compounds (only carbon dioxide) -respiration -complete combustion of hydrocarbons

Question 30

how is methane formed

Answer 30

-decomposition of vegetation -waste gas from digestion of animals

Question 31

example of greenhouse gases

Answer 31

-carbon dioxide -methane

Question 32

why is methane not used as a fuel

Answer 32

it is a worse greenhouse gas than carbon dioxide

Question 33

ways to reduce climate change

Answer 33

-planting trees -reduction in livestock farming -decreasing use of fossil fuels -increasing use of hydrogen and renewable energy, e.g. wind, solar

Question 34

how to reduce sulfur dioxide

Answer 34

-use flue desulfurization - react sulfur dioxide with calcium carbonate to make calcium sulfite and carbon dioxide CaCO3 + SO2 -> CaSO3 + CO2

Question 35

how to reduce nitrogen oxides, carbon monoxide & hydrocarbon

Answer 35

-use a catalytic converter - uses a platinum as a catalyst to speed reaction (provide path with lower activation energy) CO + O2 -> CO2 hydrocarbon + O2 -> CO2 + water 2NO + 2CO → 2CO2 + N2

Question 36

which gases are released in 1) combustion of fuels 2) petrol combustion in cars 3) combustion in air from cars

Answer 36

1) CO, CO2, SO2 2) CO, SO2 3)NO, NO2, hydrocarbons

Question 37

reaction between all hydrocarbon & oxygen

Answer 37

hydrocarbon + oxygen -> carbon dioxide + water

Question 38

ways to reduce pollutants

Answer 38

-use low sulfur fuels -use flue gas desulfurization -use catalytic converter

Question 39

define rusting

Answer 39

oxidation of iron (iron oxide)

Question 40

things needed for rusting

Answer 40

-water -oxygen

Question 41

compound in unpolluted air

Answer 41

water vapor

Question 42

elements in unpolluted air

Answer 42

-nitrogen -oxygen -argon

Question 43

uses for water 1) industry 2) house

Answer 43

1) cleaning, making clothes 2) drinking, showering

Question 44

note: there is more argon than any other gases in the 1%

Question 45

note: -sulfur dioxide can be used to manufacture sulfuric acid -carbon dioxide is made in fermentation -carbon dioxide & metal oxide is made in thermal decomposition of metal carbonates -combustion of hydrocarbons result in carbon dioxide & water -household water contains salts -incomplete combustion = insufficient oxygen