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Chemistry (N.A.) > UNIT 10 Chemistry of the environment [self-taught] > Flashcards

UNIT 10 Chemistry of the environment [self-taught] Flashcards

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1
Q

one use of water

  • in the home
  • industrial
A
  • washing / cooking / cleaning / sanitation
  • cooling / as a solvent
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2
Q

chemical tests for water

A

anhydrous / blue cobalt (II) chloride goes pink

anhydrous / white copper (II) sulfate goes blue

MP 0, BP 100

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3
Q

what do impurities do to BP

A

increase the boiling point of water, so above 100 oC

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4
Q

& to MP

A

decrease the melting point of water, below 0 oC

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5
Q

eqns for cobalt (II) chloride

SIXXX MOLES OF WATER

A
  • anhydrous cobalt(II) chloride + water ⇌ hydrated cobalt(II) chloride

CoCl2 (s) + 6H2O (l) ⇌ CoCl2*6H2O (s)

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6
Q

eqns for copper (II) chloride - COPPER 5 COPPER 5

A

anhydrous copper(II) sulfate + water ⇌ hydrated copper(II) sulfate

CuSO4 (s) + 5H2O (l) ⇌ CuSO4*5H2O (s)

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7
Q

WHY distilled water (water that has been heated to form a vapour, and then condensed back to a liquid)

.. is used in practical chemistry rather than tap water

A

it contains fewer chemical impurities

  • if impure, could interfere with chemical reactions
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8
Q

unpolluted air - gases

A

78% nitrogen
21% oxygen
approx 1% argon
0.04% co2
remainder: other gases

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9
Q

one environmental consequence of an increase in the percentage of carbon dioxide

A

global warming / ice-caps melting

  • water levels rise as glaciers melt bc of high temperatures, causing flooding in low-lying countries
  • extinction of species due to the destruction of natural habitats
  • migration of species as they will move to areas that are more habitable (no droughts)
  • spread of diseases caused by warmer climate

-loss of habitat due to climate change

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10
Q

State that water from natural sources may
contain substances, including:

A

dissolved oxygen, metal compounds, plastics, sewage, harmful microbes, nitrates from fertilisers, phosphates from fertilisers and detergents

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11
Q

some (2) substances beneficial - which? why?

A
  • dissolved oxygen for aquatic life
  • some metal compounds provide essential minerals for life
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12
Q

some (4) of these substances are
potentially harmful

A
  • some metal compounds are toxic
  • some plastics harm aquatic life
  • sewage contains harmful microbes which
    cause disease
  • nitrates and phosphates lead to
    deoxygenation of water and damage to
    aquatic life
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13
Q

treatment of domestic water supply (filtration -> carbon -> chlorination)

  1. sedimentation / filtration -

to remove solid, insoluble impurities

A

water is pumped into sedimentation tanks and allowed to stand for a few hours

mud, sand and other particles will fall to the bottom of the tank due to gravity and form a layer of sediment

the water is then filtered through sand and gravel to remove smaller particles

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14
Q
  1. filtration / treatment with carbon
A

removes unpleasant tastes and odours

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15
Q
  1. chlorination
A

Bacteria and other microorganisms are too small to be trapped by the filters

so chlorine is carefully added to the water supply to kill bacteria and other microorganisms

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16
Q

what is used as fertilisers

e.g., NH4NO3, (NH4)3PO4, KNO3

A

ammonium salts and nitrates are used
as fertilisers

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17
Q

NPK? for?

A

nitrogen, potassium and phosphorus

for improved plant growth

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18
Q

functions & sources -

  1. nitrogen
A

makes chlorophyll and protein and promotes healthy leaves

  • NH4+ and NO3-, are sources of soluble nitrogen
19
Q
  1. potassium
A

promotes growth and healthy fruit and flowers

  • Most common potassium compounds dissolve in water, produce K+
20
Q
  1. phosphorus
A

promotes healthy roots

  • Phosphate ions, PO43- are a source of soluble phosphorus
21
Q

source of each of these FIVE air pollutants

  1. CO2
A

from the complete combustion of carbon-containing fuels

e.g, methane COMPLETE
CH4 + 2O2 → CO2 + 2H2O

22
Q
  1. CO & particulates
A

from the incomplete combustion of carbon-containing fuels

e.g. INCOMPLETE - gasoline/octane, methane (C & CO)
C8H18 + 9O2 → 5CO + 2CO2 + 9H2O

2CH4 + 3O2→ 2CO + 4H2O
CH4 + O2→ C + 2H2O

23
Q
  1. CH4 (methane)
A

from the decomposition of vegetation and waste gases from digestion in animals

24
Q
  1. oxides of nitrogen
A

from car engines -

nitrogen and oxygen react in the high pressure and temperature conditions of internal combustion engines and blast furnaces

25
Q
  1. SO2 (sulfur dioxide)
A

from the combustion of fossil
fuels which contain sulfur compounds

26
Q

adverse effect of these SIX air pollutants

  1. CO2 & 4. methane
A

higher levels of carbon dioxide/methane leading to increased global warming, which leads to climate change

27
Q
  1. CO
A

toxic gas

-combines with haemoglobin in the blood and prevents it from carrying oxygen

28
Q
  1. particulates
A

increased risk of respiratory problems and cancer

29
Q
  1. oxides of nitrogen
A

📌 acid rain [dissolves in rain to form acid rain which causes corrosion to metal structures & damage to aquatic organisms],

📌 produces photochemical
smog

📌 respiratory problems

30
Q
  1. SO2
A

acid rain

31
Q

sun emits energy…

how is thermal energy reflected/absorbed/emitted?

A

Sun’s rays enter the Earth’s atmosphere. Some thermal energy is reflected from the Earth’s surface.

MOST thermal energy is absorbed and re-emitted back from the Earth’s surface, where some thermal energy passes straight through and is emitted into space

32
Q

thermal energy is _____ by greenhouse gases…

A

📌 some thermal energy is absorbed by greenhouse gases, such as carbon dioxide and methane, and is re-emitted in all directions

33
Q

what does this do? what is it called?

A

reduces the thermal energy lost into space and traps it within the Earth’s atmosphere, keeping the Earth warm

greenhouse effect

34
Q

what is enhanced greenhouse effect?

A

As the concentration of greenhouse gases in the atmosphere increases due to human activity,

📌more thermal energy is trapped within the Earth’s atmosphere causing the Earth’s average temperature to rise (global warming)

35
Q

strategies to reduce the effects
of 1. climate change

A

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

36
Q

of 2. acid rain

A

use of catalytic converters in vehicles,
reducing emissions of sulfur dioxide by using low-sulfur fuels and flue gas desulfurisation with calcium oxide

37
Q

flue gas desulfurisation

A
  • waste gases from coal fired power stations are passed into a scrubbing chamber
  • they are sprayed with a wet slurry of calcium oxide and calcium carbonate
  • the calcium compounds react with sulfur dioxide to produce calcium sulfate
38
Q

catalytic converters

A
  • contain a series of transition metal catalysts including platinum and rhodium
  • metal catalysts are in a honeycomb within the converter to increase the surface area available for reaction
39
Q

series of redox reactions, neutralise pollutant gases -

EACH STEP & EQN

A
  1. Carbon monoxide is oxidised to carbon dioxide:
    2CO + O2 → 2CO2
40
Q

2.

A

oxides of nitrogen are reduced to N2 gas:

2NO → N2 + O2

2NO2 → N2 + 2O2

41
Q

3.

A
  • summarise the reaction of nitrogen monoxide and carbon monoxide within a catalytic convertor:

2NO + 2CO → N2 + 2CO2

42
Q
  1. 12.5 OXYGENS.
A

Unburned hydrocarbons can also be oxidised to carbon dioxide and water:

C8H18 + 12½O2 → 8CO2 + 9H2O

43
Q

photosynthesis

A

the reaction between carbon dioxide and water to produce glucose and oxygen in the presence of chlorophyll and using energy from light

44
Q

word & symbol eqns

A
  • carbon dioxide + water → glucose + oxygen
  • 6CO2 + 6H2O → C6H12O6 + 6O2

Chemistry (N.A.) (10 decks)

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