organic chemistry Flashcards
(40 cards)
nonrenewable resources
those that are used faster than they can be replenished.
non-renewable fuels
Coal, oil and natural gas
fuel
a substance with stored energy that can be released relatively easily, for use as heating or power.
how are fossil fuels made?
fossil fuels are made from ancient plants, animals and micro organisms that contain carbon and hydrogen, that are buried under tons of mud, sand and rock thus located in the earth’s crust. These biological material undergo complex changes to become fossil fuels. these can be burned for energy.
how is coal formed?
Coal is formed from ancient plants, animals and micro-organisms that are buried under tons of mud, sand and rock. Once this biological material has undergone complex changes to become fossil fuels for example , coal , oil and natural gas . The organic matter still retains some of the chemical energy of the plants originally accumulated by carrying out photosynthesis . The chemical energy in fossil fuels can be considered as trapped solar energy .
combustion reaction for Coal
C + O2 → co2
fuels from crude oil (petroleum)
petroleum, or crude oil is a mixture of hydrocarbon molecules that are mostly alkanes. Crude oil is no use as a fuel until its components can be separated (by fractional distillation) into petrol, diesel, kerosene, and LPG. LPG is liquified petroleum gas.
how is natural gas made?
Natural gas is another fossil fuel found in deposits in the earths crust. It is drilled out and comes to the surface. The extraction of natural gas from coal or shale deposits usually involves fracking. This process is where the sand, water and other chemicals are injected into the deposit at high-pressure to free the gas from coal or shale. However, fracking can impact the local environment and underwater supplies due to the chemicals that are injected into the deposit. natural gas, is it composed, mainly of methane and small amounts of ethane and propane. Water, sulfur, carbon dioxide and nitrogen might also be present in natural gas.
Complete combustion
where fuels are ignited in excess air (oxygen) and they produce carbon dioxide, water and releases considerable amounts of energy
incomplete combustion
occurs if o2 supply is limited (insufficient) and carbon monoxide and even soot C(s) can be produced
hypoxia
The emission of carbon monoxide from the fuel’s incomplete combustion can cause hypoxia.
the kyoto protocol
an objective of the United Nations Framework Convention on Climate Change (UNFCCC) to reduce the onset of global warming by reducing greenhouse gas emissions.
energy density
The amount of energy stored (in a system) per unit mass e.g. units are usually J/L, J/m^3
What is photochemical smog?
Photochemical smog is a toxic mixture of various chemical pollutants produced when sunlight interacts with car exhaust gases.
catalysts
Certain chemical substances, known as catalysts, have the ability to speed up chemical reactions while they remain chemically unchanged at the end of the reaction.
Which metals are used in a vehicle catalytic converter and what do each of them do?
Its operation relies on the catalytic ability of metals like platinum, palladium and rhodium to rapidly convert toxic and polluting vehicle exhaust gas into harmless nontoxic substances.
harmful gases /pollutants car engines emit
carbon
monoxide (CO) nitrogen oxides (NO) and various unburnt hydrocarbons.
biofuel stands for…
biochemical fuels
what are biofuels made from?
biochemical fuels (biofuels) are derived from plant materials, such as grains (maize, wheat, Bali, sorghum), sugar, cane, vegetable waste, and vegetable oils.
why are biofuels carbon neutral?
The plant materials used in making biofuels are produced by photosynthesis, which removes carbon dioxide from the atmosphere and produces glucose. During fermentation, the extracted sugars from these plants are converted into ethanol, releasing CO2 as a byproduct. When ethanol is used as a fuel and burned, it releases CO2 back into the atmosphere. Although carbon dioxide is released back into the atmosphere when the biofuel is burnt, the net impact should be less than the net impact for fossil fuels. The use of biofuels can therefore be described as carbon neutral, although there will be some carbon emissions from the manufacturing distribution of biofuels. Therefore, they will always be some net emissions associated with their use.
bioethanol
biological catalysts called enzymes, from yeast, convert starches, and sugar into ethanol. Enzymes catalyse the starch in grain crops, such as barley and wheat, to glucose. Fermentation is a process that uses other enzymes from use to convert glucose, into other small sugar molecules to ethanol and carbon dioxide. Fermentation is an anaerobic process that takes place in the absence of oxygen. Bioethanol is used extensively in Australia, including E10 petrol, which it contains 10% ethanol, which reduces the total amount of carbon dioxide that is released into the atmosphere. E10 fuel also reduces unburnt carbon and gases like oxides of nitrogen that are emitted by exhaust and contribute to air-pollution
biogas
biogases are released from the breakdown of organic waste by anaerobic bacteria into carbon dioxide and methane. A digester is a large tank filled with anaerobic bacteria that digest the complex molecules to form biogas. Biogas is a renewable energy source that is primarily composed of methane (CH4) and carbon dioxide (CO2), with small amounts of other gases. It is produced through a natural biological process called anaerobic digestion, which involves the action of bacteria in the absence of oxygen. This process typically occurs in environments where organic matter, such as agricultural waste, sewage, or food waste, is broken down by microorganisms in the absence of oxygen.
biodiesel
biodiesel Is a make mixture of organic compounds called esters, which are produced by chemical reactions between vegetable oils and animal fats and an alcohol, most commonly methanol. Most commonly vegetable oil from sources, such as soybean, canola, or Palm oil. Recycled vegetable oil, or animal fats can be used. Biodiesel is very similar to petrol diesel, so it is possible to run vehicles on 100% biodiesel fuel. Biodiesel is biodegradable and non-toxic and produces fewer pollutants in vehicle emissions. Like ethanol, biodiesel does not add to the overall amount of carbon dioxide already present in the atmosphere as the creation of the raw materials that make biodiesel take carbon dioxide from the atmosphere.
fossil fuels vs biofuels
fossil fuels have a higher nature of products of combustion (carbon emissions) than bio fuels
fossil fuels have a higher energy output than bio fuels
suitability:
fossil fuels:
- higher energy density
biofuels:
- less environment impact than fossil fuels
- renewable source of energy
