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Chemistry > Chemical Monitoring and Management > Flashcards

Chemical Monitoring and Management Flashcards

1
Q

Why is it important for chemists to collaborate?

A
  • people with higher levels of expertise can share knowledge

- specialist chemists bring a variety of knowledge

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2
Q

Why does combustion need to be monitored?

A

-If Oxygen is limited, alternative (harmful) substances are produced e.g. CO

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3
Q

Identify industrial uses of Ammonia

A
  • House hold cleaners
  • Fertilisers
  • Nitric Acid
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4
Q

How is ammonia synthesised?

A

-reacting its gaseous elements: N & H:

N2 + 3H2 –> 2NH3

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5
Q

Why is the Haber process significant in world history?

A
  • nitrogenous raw materials were dwindling

- naval blockade & exhausted supplies would have meant a much shorter war

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6
Q

What kind of reaction is the synthesis of ammonia?

A

Reversible reaction that will reach equilibrium-ammonia is formed from nitrogen & hydrogen & then Nitrogen and Hydrogen are formed from the ammonia

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7
Q

Is the reaction of hydrogen & nitrogen exothermic or endothermic?

A

forward reaction is exothermic releasing 46kJ of energy for each mole of NH3 formed

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8
Q

What impact does increased temps have on the rate of reaction

A
  • Increased rate of reaction as the particles move more quickly
  • yield decreases-Le Chatelier’s principle means that the equilibrium will move to the left
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9
Q

Why is the Haber process based on a delicate balancing act?

A
  • increasing temp increases reaction rate but decreases yield
  • lowering temp increases yield but reduces reaction rate
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10
Q

What would be optimal balanced conditions for the haber process?

A

Medium temps: 500degrees

Pressure: 250atmospheres

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11
Q

What is the impact of a catalyst in the Haber process?

A

catalyst (Fe3O4) allows a lower temp to be used

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12
Q

Why is it important for the reaction vessel to be monitored?

A
  • temp too high can cause damage to the catalyst
  • any contaminants can interfere
  • ensure O2 is absent to avoid risk of explosion
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13
Q

Why do ion levels need to be monitored?

A

Ions e.g. lead can be very toxic & cause pollution if levels are unsafe

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14
Q

What impact has AAS had on the understanding of the effects of trace elements?

A
  • previous techniques weren’t sensitive enough to measure small quantities
  • scientists can work out how trace elements assist in the healthy functioning of organisms
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15
Q

Describe the composition & layered structure of the atmosphere

A
  • Troposphere: life, weather, aircraft
  • Stratosphere: ozone layer
  • Mesosphere
  • Thermosphere
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16
Q

Identify the main pollutants found in the lower atmosphere & their sources

A
  • CO: incomplete combustion, cars, fires
  • NOx: Combustion @ high temps in vehicles& power stations
  • SO2: burning of fossil fuels
  • Lead: leaded fuels, metal extraction
17
Q

Describe Ozone in the lower atmosphere & Upper atmosphere

A
  • lower atmosphere: poisonous, strong oxidant-pollutant

- upper atmosphere: UV radiation shield blocking harmful rays from passing through

18
Q

How are coordinate covalent bonds formed?

A

one atom in a species provide both electrons in the covalent bond e.g. ammonium

19
Q

Identify the origins of Chlorofluorocarbons & halons

A
  • developed to replace ammonia as a refrigerant
  • properties made them very useful
  • Halons used extensively in fire extinguishers
20
Q

How are ozone levels measured?

A
  • satellites carry total ozone mapping spectrophotometers

- UV spectroscopes attached to telescopes

21
Q

How have atmospheric ozone concentrations changed?

A
  • atmospheric chlorine amounts have increased from around 0.5ppb to 3.5ppb
  • between 1983-1985 ozone levels reduced by 50%
  • Ozone layer is most depleted over Antarctica & during Spring
22
Q

Identify alternative chemicals used to replace CFCs

A
  • Hydrochlorofluorocarbons:

- Hydrofluorocarbons: main replacement

23
Q

What problems are associated with the use of CFCs?

A
  • depletion of the ozone layer
  • more UV radiation reaching Earth
  • Increase in enhanced greenhouse effect
24
Q

How can water quality be determined?

A
  • Concentrations of common ions
  • Total dissolved solids
  • Hardness
  • Turbidity
  • Acidity
  • Dissolved Oxygen
  • Biochemical Oxygen Demand
25
Q

What factors affect the concentrations of ions in solution in natural bodies of water?

A
  • Frequency of rainfall
  • Water temp
  • evaporation rates
  • pH of the rain
  • discharges of pollution

Chemistry (4 decks)

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