Carbon Chemistry - Effects of combustion on environment Flashcards
What is the difference between renewable and non-renewable fuel?
Renewable fuel resources can be replaced and will not run out eg biofuels, biodiesel and hydrogen gas
Non-renewable fuels cannot be replaced once they are used up eg petrol, diesel, natural gas, coal, and crude oil.
What is the source of fossil fuels?
Fossil fuels are formed from the remains of living things. Millions of years of heat and pressure changed the remains of plants and animals into fossil fuels.
What do fossil fuels contain?
Fossil fuels are carbon-based compounds, so they contain carbon along with other elements such as hydrogen and oxygen
Describe the carbon cycle
Large amount of carbon exists as CO2 in the atmosphere. CO2 is absorbed and used by plants in the process of photosynthesis and this produces organic molecules such as sugars.
Consumers then consume this plant material.
Animals and plants release CO2 back into the atmosphere by respiring.
Decomposers (fungi and bacteria) break down dead organic matter, releasing CO2 back into the atmosphere.
If decomposition is prevented then the animal and plant material may be then available as fossil fuel for combustion.
When fossil fuels are burned, carbon dioxide is also released back into the air.
Why are decomposers essential?
Because without them, all of the carbon on the planet would eventually become locked up in dead carcasses and other waste.
Outline the greenhouse effect
-The earth’s atmosphere acts like a blanket around the Earth. If the earth had no atmosphere then the surface temperature would be -18°C. After the sun goes down the temperature would be -160°C as the surface would lose heat to space very quickly.
The atmosphere’s ability to keep the Earth warm is called the “Greenhouse effect”. About 80-90% of the Earth natural greenhouse effect is due to water vapour, a strong greenhouse gas. The remainder is due to carbon dioxide, methane and a few other minor gases.
- Solar radiation passes through the atmosphere
- Some solar radiation is reflected by the atmosphere and the Earth’s surface
- Solar radiation is absorbed by the surface, warming it. The warm surface radiates heat as infrared radiation.
- Greenhouse gases reflect some of the infrared radiation back to the Earth, making the Earth warmer.
How is acid rain formed?
When fossil fuels such as coal, oil and natural gas are burned, oxides of carbon, sulfur and nitrogen escape into the air. These molecules dissolve in the water in the clouds and make the rainwater more acidic than normal. When this happens it is called acid rain.
What are the environmental problems of acid rain?
- Stonework and metalwork can be corroded
- Acidic water is harmful to fish and other wildlife in waterways
- Acidic water stunts plant growth and kills them due to lower pH of soil.
How does ocean acidification occur?
The oceans absorb about 1/4 of the CO2 in the atmosphere, so as CO2 in the atmosphere increases so do the levels in the ocean.
-Photosynthetic plants benefit from this as they require CO2 to live.
Effects of ocean acidification?
- Photosynthetic plants benefit from this as they require CO2 to live.
- But, the chemistry of the seawater is also changing - ocean acidification.
CO2 reacts with water to form carbonic acid
The carbonic acid lowers the pH of the oceans and affects the formation of shells, corals and plankton because acids are corrosive. Many of these organisms play key roles in marine food chains. Without them, there could be no other marine life.
Discuss biofuels
Ethanol can be used to fuel vehicles and for heating. It can be manufactured by fermenting plant material. Plants remove CO2 and it is released again when ethanol is combusted. In theory, this should result in no net increase in atmospheric CO2 as stored carbon in fossil fuels isn’t being released.
