Unit 2.3 The impact of chemistry Flashcards
What’s the main thing of this topic?
Sustainability, efficiency, effectiveness, biodegradable
In addition,
Non-renewability, waste products, global warming, excessive dependence
Ya name them
U know what, I may copy word for word. For sure at the end, I’ll break it down, riggghhhtt?
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Considering the impact of chemistry?
Our lifestyles demand goods and services, these are our social requirements. Being able to produce things cheaply is economic considerations. However, we need to consider environmental issues which may have social and economic consequences (inconvenient or costly)
- World resources are running out and are non-renewable
- We need to reduce the waste of valuable resources
- Reduces the expense of disposal
- Reduces the expense of making things from raw materials
- Avoids environmental problems posed by waste:
1. Landfill
2. Greenhouses gases
3. Acid rain
4. Pollution
5. Destroying habitats
6. De-forestation leading to climate change and destruction of ecosystems
Basics[?] of considering the impact of chemistry?
- Better way to prevent waste than to treat it afterwards
- Aim for maximum atom economy
- Use processes which require fewer chemicals
- Unsure chemicals, methods and solvents are as safe as possible:
1. Avoid any that are toxic or dangerous to human health
2. Avoid any that are harmful to the environment
3. Avoid accidents
4. Design for biodegradation - Reduce the energy requirements of processes
- Use alternative or renewable energy resources
- Use renewable raw materials, not finite resources
- Use catalysts where possible
- Waste products should be designed to be biodegradable
- Reduce the risk of explosions and fires
When looking at products (and reactants) what implications must u consider of their use?
- Is this the most efficient process?
Is there a better reaction we could use that wastes less? - Where should the industry be sited?
Consider social, economic and environmental issues - Are the by-products, products and reactants safe?
Can we use anything less toxic or explosive? - Is the process environmentally damaging?
Does it cause pollution or destroy habitats?
Which chemical industry, what do they mainly require?
- Transport links
- Good source of trained labour
- Access to raw materials and power
For chemical engineers running industrial processes, what 2 extremely important tasks that must be undertaken?
- A mass balance
- An energy balance
Explain a Mass balance?
- Involves accounting for total mass of reactants and total mass of products
- Including waste products and emissions
- Unit 1.3 principles & equations = important
- For unfamiliar processes all relevant data will be given
How to find % yield?
(What u actual get/what u theoretically get) x 100
or
(mass of product obtained/maximum theoretic yield) x 100
How to find atom economy?
(mass of required product/total mass of reactants) x 100
I mean, mass or mr, same thing
Explain an Energy balance?
- Involves accounting for total input of energy and total output of energy
- Including waste energy given out to environment
- Students should appreciate the role of water as a cooling medium to remove heat evolved in the process
What are the 2 factors to consider for the development of a chemical process?
- Social implications
- Economic factors
Explain social implications?
Includes:
- Availability of labour
- Impact on local amenities
- Use of land (brown field v green field sites)
Explain economic factors?
Oh boy… I’m writing everything.
Siting the plant:
Depending upon the scale of operation, choices have to be made and these will be commercial decisions. Local Authority planning permission must be granted for any new development. There may be financial incentives to set up in some areas. Transport considerations are important. Many new plants are set up in or around existing concentrations of industry since there are relatively few companies that have sufficient wealth to start a new venture. Where existing concentrations of industry exist, there are likely to be existing transport and communication links, a working population to employ and availability of services such as energy and water
Why do we need energy?
Hmm, very tangible answer….
State some non-renewable sources
- Oil
- Natural gas
- Coal
- Nuclear energy
State some renewable sources?
- Wind power
- Solar power
- Bioenergy (organic matter burned as fuel)
- Hydroelectric (including tidal energy)
Benefit of improving efficiency?
- Reduce energy requirements
Research into car engines is fairly successful, it leads to reduction in costs. This has the advantage of being popular with customers who save money on fuel costs
Describe hydrogen as a fuel source?
- Advantage of being renewable
- Can obtain from [water?/wind, solar, geothermal, or biomass?]
- Doesn’t produce pollution
- Waste product is water
Disadvantages are that hydrogen is not naturally occurring (on Earth) and energy is needed to produce it
What is carbon neutral?
A chemical process such as fuel combustion does not lead to an overall increase in CO2 levels. Although combustion does generate CO2, this is offset by the fact that the fuel, such as biomass or sugar cane, has absorbed the same amount of CO<sub”</sub> i being made by photosynthesis
Uhhh…. isn’t there a simpler way?
Why is carbon neutrality important?
Benefits to communities and society as a whole. They include:
- Less environmental pollution
- Improvements to health
- A boost to sustainable economic growth and the creation of green jobs
What is biomass?
Carbon neutral
Leaves a zero carbon foot-print
What are the processes that mean biomass is not carbon neutral?
Needs to be harvested, transported and buildings need to be built to burn it in- all these require carbon
Describe renewable energy
Sources produced by physical processes are theoretically, non-polluting, however turbines, generators and transport of electricity all require forms of construction and therefore require energy
Many are very inefficient. No need to look at these processes as they are interested in chemical processes
Describe nuclear power
Radioactive fission of uranium converts mass (around 1%) into energy. Around 20% of our countries energy could be produced this way
Problems with nuclear power?
- Massive costs to build and decommission power plants
- Extremely dangerous consequences of radiation leaks
- Difficulty of storing the highly radioactive waste safely
What would be a much safer nuclear power method?
Nuclear fission of hydrogen into helium (as in the sun):
- Theoretically more safer (no radioactive reactants/products)
- More efficient process
To date unfortunately, this process cannot be achieved technically
Describe solar power
Solar power panels can directly heat water. However, to produce electricity semiconductor panels (using silicon or gallium arsenide) are now often over 10% efficient and becoming more popular. Power outputs of 0.5kWm-1 are being achieved
- Just increased efficiency and usage
How does a catalyst reduce the temperature needed for a successful reaction?
Provides an alternate route with a lower activation energy
Define VOCs
Volatile organic compounds: bad for the environment
e.g. Diesel engines
Give off nitrogen oxides which cause acid rain. Addition of ammonia converts these into harmless nitrogen
Major disposal problem of widespread use of addition polymers?
- Bonds within polymers are strong, covalent and non-polar
- Makes most polymers resistant to chemical attack
- Non-biodegradable as it can’t be broken down by bacteria
- Causes problems trying to dispose
e.g. Plastic waste buried in landfill sites
They remain unchanged for decades ∴ current landfill sites fill very rapidly with the quantities of plastic material we throw away
What are the alternative methods of dealing with polymer waste other than landfill?
- Recycling
- Polymers as a fuel source
- Feedstock recycling
- Biodegradable and compostable polymers
Explain recycling
- Simple and cheap
- By reusing polymer without processing
- However only possible in very few cases
More common to have to process the polymers by first sorting them and then reclamation
Sorting is a difficult process…
Explain polymers as a fuel source
- Burning polymer waste as a method of generating electricity
- Problem: certain polymers e.g. PVC can release toxic fumes when burnt
- Incinerators must be equipped of ways of dealing with harmful emissions
Explain feedstock recycling
- Polymers cracked into chemicals
- Used to produce new polymers or other organic chemicals
- Some chemicals produced during cracking may be used as fuel
All these methods are ways in which we are reducing the amount of crude oil…
Explain biodegradable and compostable polymers
- Lots of research done
- Into producing polymers from renewable raw materials
- Where monomers come from plants and animals
- These new polymers degrade much more quickly in landfill sites
Honestly the rest, look in booklet. This just kinda stupid to have this many cards and learning all these. And it’s not even any calculation this a whole history lesson
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