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Chemistry > Life Cycle Assessments > Flashcards

Life Cycle Assessments Flashcards

1
Q

What is the purpose of a life cycle assessment (LCA)?

A

To analyze the stages of a product’s life cycle and assess its environmental impact

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2
Q

What are the four stages of an LCA?

A
  1. Extracting and processing raw materials.
  2. Manufacturing and packaging.
  3. Using the product.
  4. Disposing of the product.
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3
Q

What environmental impacts occur during raw material extraction?

A

Direct damage to the environment, such as deforestation or mining, and pollution from energy-intensive processes

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4
Q

What are three main issues during manufacturing and packaging?

A
  • High energy use
  • Pollutant release (e.g., carbon monoxide)
  • Waste production
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5
Q

How does the use of a product affect its environmental impact?

A

It depends on how polluting the product is during use and how long it lasts

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6
Q

What are two main disposal methods and their impacts?

A
  • Landfill: Takes up space and can pollute ecosystems
  • Incineration: Releases pollutants into the air
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7
Q

Compare plastic bags and paper bags during raw material extraction

A
  • Plastic bags: Made from crude oil (a finite resource).
  • Paper bags: Made from wood (deforestation)
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8
Q

Compare plastic bags and paper bags during disposal

A

Plastic bags - Non-biodegradable, can harm wildlife
Paper bags - Biodegradable and non-toxic.

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9
Q

What are two major limitations of LCAs?

A
  • They are complex and hard to quantify accurately
  • They can be manipulated for positive advertising
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10
Q

What is potable water?

A

Water that is safe to drink

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11
Q

What are the three criteria for potable water?

A
  • Low levels of dissolved substances.
  • A pH between 6.5 and 8.5.
  • No microorganisms like bacteria or fungi.
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12
Q

What are two types of fresh water sources?

A
  • Surface water: Lakes, rivers, reservoirs
  • Groundwater: Aquifers (permeable rock trapping water)
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13
Q

Why might surface water not always be reliable?

A

It can dry up in hot, sunny weather because it’s exposed to the sun

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14
Q

What are the three steps to treat fresh water?

A
  • Wire mesh filtration: Removes large debris.
  • Sand and gravel filtration: Removes smaller particles.
  • Sterilization: Kills microorganisms using chlorine gas, ozone, or ultraviolet light
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15
Q

What is desalination, and when is it used?

A
  • The extraction of potable water from sea water
  • Used in areas with low rainfall
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16
Q

Describe the distillation process for desalinating seawater

A

Boiled to produce water vapor, which is then condensed into pure water

17
Q

How does reverse osmosis desalinate seawater?

A

Salty water is passed through a semi-permeable membrane that only allows water molecules through, trapping larger molecules and ions

18
Q

What are the limitations of desalination?

A
  • Requires lots of energy.
  • Is expensive.
  • Impractical for producing large quantities of potable water
19
Q

What is an aquifer?

A

A layer of permeable rock underground that traps fresh water

20
Q

What are the three main sources of wastewater?

A
  • Domestic: Household waste (e.g., showers, sinks, toilets).
  • Agricultural: Nutrient runoff and animal waste.
  • Industrial: Wastewater from factories containing harmful chemicals.
21
Q

Why does wastewater need to be treated?

A

To remove organic matter, harmful microbes, and toxic chemicals to make it safe for disposal or reuse

22
Q

What is the first step in sewage treatment?

A
  • Screening: Large debris like twigs and plastic bottles are removed using a mesh
23
Q

What happens during sedimentation in sewage treatment?

A
  • Heavy solids sink to the bottom, forming sludge.
  • The lighter liquid (effluent) remains at the top and is separated.
24
Q

How is organic matter broken down in sewage treatment?

A
  • Effluent: Broken down by aerobic digestion (oxygen is pumped in).
  • Sludge: Broken down by anaerobic digestion (sealed tank with no oxygen)
25
Q

What are the products of anaerobic digestion in sludge treatment?

A
  • Methane: Used as an energy source.
  • Digested waste: Used as a nutrient-rich fertilizer.
26
Q

How is toxic wastewater treated?

A
  • Adding chemicals to precipitate out metals.
  • Using UV radiation to break down harmful substances.
27
Q

Why is wastewater treatment preferred over seawater desalination?

A
  • Easier
  • Requires less energy
  • Cheaper than desalination
28
Q

What is effluent, and what happens to it after treatment?

A

Is the lighter liquid from sedimentation. After aerobic digestion, it is safe to release into the environment

29
Q

What is sludge, and how is it treated?

A

The heavier solid waste from sedimentation. It undergoes anaerobic digestion, producing methane and fertilizer

30
Q

Name two countries or regions where wastewater treatment is crucial for drinking water

A
  • Singapore
  • other areas with limited water supplies

Chemistry (8 decks)

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