NUCLEAR ENERGY: Juan and Clifford

NUCLEAR ENERGY

BY: CLIFFORD AND JUAN

1) About Nuclear Energy:

- Nuclear energy is one of the cleanest source of energy that produces energy efficiently. It is very conservative form of energy as the same amount of Uranium-235 produces 10 million times more energy than the same amount of coal burnt. However, maintaining a nuclear power plant is very troublesome and dangerous as there are mountains of radioactive wastes as well as getting near the plant is very radioactive.

ßß Example of a Nuclear Power Plant

2) Pros and Cons of Nuclear Energy (Blue = pros, Red = cons):

- It produces almost no greenhouse gases, reducing global warming problems.

- It is a very reliable energy source, because very little reactants to produce energy is needed everytime, hence there are almost never shortage of supply.

- By far, nuclear power plant produces the most energy out of the rest of the energy power plant. Nuclear power plant produces phenomenal amounts of energy despite its little requirements to produce.

- Although nuclear power plants do not emit greenhouse gases, they produce radioactive wastes, which are harmful to the environment and they are very difficult to remove.

- Nuclear power plants are very difficult to manage and very dangerous. These power plant expose workers to excessive radiation, which harms their lives. Even during the mining of Uranium-235, exposure to radioactivity is possible.

- Nuclear power plants are prone to massive disasters. An example of this is the chernobyl incident that happened in the Ukraine in 26th of April 1986.

ßß Cross section of a nuclear power plant.

ßß Aftermath of the Chernobyl Disaster.

3) How is the nuclear energy formed?

- A nuclear power plant produces its energy from Uranium-235. Energy is produced through a process called nuclear fission. In nuclear fission, neutrons collides with the Uranium-235 atoms, creating an unstable atom. These atoms then split, producing huge amounts of energy while splitting. However, after the split, neutrons are released by the atoms, creating more neutrons to collide with another Uranium-235 atoms, creating a chain reaction. The energy produced is calculated by a famous Einstein equation, E= mc² where E= energy, m= mass, and c = speed of light (3x10⁸ m/s). That is a humongous amount of energy.

- This amount of energy is released by rods of Uranium-235, into the water and the water turned into steam. These steams then turn the turbines to produce energy.

- Other methods of producing energy (nuclear energy) is possible. Examples of it are nuclear fusion and etc.

http://www.youtube.com/watch?v=N7C14UIKuv8 à This is a video explaining the nuclear fission in detail.

ßß Illustration of a nuclear fission.

4) The uses of nuclear energy

- Food and Agriculture
The use of isotopes and radiation techniques in agriculture come under this category. Leading organizations have been working on the technology to increase agricultural production, improve food availability and quality, reduce production costs and minimize pollution of food crop.

- Human Health
One very common application of nuclear energy is in the treatment of cancer - radiotherapy. Radiotherapy can also be used to cure cancers like breast cancer, lung cancer, etc. Also, small amounts of radioisotope tracers are used for diagnostic and research purposes. These techniques have helped in monitoring the levels of toxic substances in food, air and water. This is one of the benefits of using nuclear energy.

5) Reasons to use nuclear energy

Reduces the Dependence on Fossil Fuels
There has been an increase in production and supply of fossil fuels like oil and gas, as the world has been using them at an tremendous pace. Their deposits are emptying. On the other hand, nuclear energy requires very little quantity of fuel to produce large quantities of energy. Consider this; one ton of uranium can produce energy that is more than that of several million tons of coal and oil.

Clean Water
The water discharged from nuclear power plants is very safe, free of any radiation or harmful pollutants, and meets all regulatory standards. Hence, helps in protecting the aquatic life and conserving wildlife. Some energy creates a pollution called water pollution and nuclear energy does not pollute the water and polluting the water can harm the aquatic lives.

REFERENCE:

http://www.buzzle.com/articles/nuclear-energy-pros-and-cons.html

http://www.buzzle.com/articles/how-does-a-nuclear-power-plant-work.html

http://www.brainpop.com/technology/energytechnology/nuclearenergy/preview.weml (Video about nuclear power plants)

Biofuel by Nicholas and Zachary

Biofuel by Nicholas and Zachary 4CH3

What is biodiesel?

Biodiesel is the name of a clean burning alternative fuel, produced from domestic, renewable resources. Biodiesel contains no petroleum, but it can be blended at any level with petroleum diesel to create a biodiesel blend. It can be used in compression-ignition (diesel) engines with little or no modifications. Biodiesel is simple to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics.

Is Biodiesel the same thing as raw vegetable oil?No!

Fuel-grade biodiesel must be produced to strict industry specifications in order to insure proper performance. Biodiesel is the only alternative fuel to have fully completed the health effects testing requirements of the 1990 Clean Air Act Amendments. Biodiesel that meets the specifications and is legally registered with the Environmental Protection Agency is a legal motor fuel for sale and distribution. Raw vegetable oil cannot meet biodiesel fuel specifications, it is not registered with the EPA, and it is not a legal motor fuel.
Biodiesel is defined as mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats which conform to specifications for use in diesel engines. Biodiesel refers to the pure fuel before blending with diesel fuel. Biodiesel blends are denoted as, "BXX" with "XX" representing the percentage of biodiesel contained in the blend (ie: B20 is 20% biodiesel, 80% petroleum diesel).

Why should I use biodiesel?

Biodiesel is better for the environment because it is made from renewable resources and has lower emission compared to petroleum diesel. It is less toxic than table salt and biodegrades as fast as sugar. This makes it a better alternative compared to diesel.

What is Biogas?
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas originates from biogenic material and is a type of biofuel. Biogas is produced by anaerobic digestion or fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, green waste, plant material and energy crops. This type of biogas consists of methane and carbon dioxide. Another type of gas generated by the use of biomass is wood gas, which is created by gasification of wood or other biomass. This type of gas consists primarily of nitrogen, hydrogen, and carbon monoxide, with trace amounts of methane.

Solid biofuels
Examples include wood, sawdust, grass cuttings, domestic refuse, charcoal, agricultural waste, non-food energy crops and dried manure.
When raw biomass is already in a suitable form (such as firewood), it can burn directly in a stove or furnace to provide heat or raise steam. When raw biomass is in an inconvenient form (such as sawdust, wood chips, grass, urban waste wood, agricultural residues), the typical process is to densify the biomass. This process includes grinding the raw biomass to an appropriate particulate size, which depending on the densification type can be from 1 to 3 cm (1 in), which is then concentrated into a fuel product. The current types of processes are wood pellet, cube, or puck. The pellet process is most common in Europe and is typically a pure wood product. The other types of densification are larger in size compared to a pellet and are compatible with a broad range of input feedstocks. The resulting densified fuel is easier to transport and feed into thermal generation systems such as boilers.
A problem with the combustion of raw biomass is that it emits considerable amounts of pollutants such as particulates and PAHs (polycyclic aromatic hydrocarbons). Even modern pellet boilers generate much more pollutants than oil or natural gas boilers. Pellets made from agricultural residues are usually worse than wood pellets, producing much larger emissions ofdioxins and chlorophenols.

So in conclusion… Use Biofuels instead of fossil fuels! Do YOUR part to save the Earth! :D

Thai Ming and Jun Xian - Green technology

Green Technology

Definition: Green Technology is technology that is designed to be safe for the environment and used in a way that doesn't consume natural resources.


There are 5 types of green technology:

1)Energy - Green technology that produces energy without consuming natural resources or harming the environment. (a.k.a Renewable sources of energy e.g. Hydroelectric)

2)Building - Designing and building houses in a way that utilises materials and tools efficiently to reduce resource consumption.

3)Preferred Purchasing - Buying and producing products that have little effect on the environment.

4)Chemistry - Using chemical products that reduce environmental damage.

5)Nanotechnology - Implementing green principles to the field of nanotechnology.

Green Energy - Green energy utilises the natural power of the earth's environment to create energy. This may include hydroelectric power stations built on waterfalls, geothermal power stations near volcanos and wind turbines around normally windy areas. With the exception of geothermal energy, green power stations directly harness the kinetic energy of the earth's environment (i.e. running water, moving wind) and uses it to create electricity by spinning a turbine. Green energy also includes methods of using energy efficiently, such as using a fan instead of air-conditioning or switching off any unnecessary lights during the day.

Green Building - Green building involves building structures in a green way, as well as designing it so that it maximises energy efficiency. This includes using materials that are quickly renewable such as bamboo (fastest growing plant in the world), building in a location that has windy areas to save on heating/air-conditioning, designing the building in a way to maintain temperature as well as providing the structure with a system to reduce water consumption.

Green Preferred Purchasing - Green preferred purchasing involves the consumer choosing green products over conventional products, such as rechargable batteries. This also extends to the producer researching methods to produce goods in a green way or producing goods that are environmentally friendly.

Green Chemistry - Green chemistry involves the creation of chemical products in a green way, and expands to the whole process of producing the desired chemical. It involves reducing any toxic waste produced, reducing pollution, using non-toxic components, creating environmentally-friendly products and reducing energy consumed in the process of making the chemical.

Green Nanotechnology - Green nanotechnology combines principles of green chemistry and green building to create nanomaterials and products that have no toxic materials, require less energy to make, and are renewable wherever possible. Green nanotechnology also involves using nanotechnology to further augment the efficiency of already existing green methods. For example, in green chemistry, the use of nanoscale membranes may help filter out unwanted products and reduce and waste.

References:
http://www.epa.gov/gcc/
http://en.wikipedia.org/wiki/Green_building
http://en.wikipedia.org/wiki/Green_nanotechnology
http://www.green-technology.org/what.htm
http://hubpages.com/hub/Green-Technology

Metallic bonding ( Desmond)

1) Metallic bonding is the electromagnetic interaction between delocalized electrons, also known as conduction electrons which are gathered in an area with alot of electrons . This also allows for metals to be ductile, strong, have better electric conductivity and also better strength to withstand heat.

2) Examples would be iron and steel but they can be of any combination so as long as they have flexible metallic bonds which allows these to carry the propeties of ductility and mallebility. The process of metallic bonding is also hard as it takes alot of practice to do it and there is still an infinite combinations of metal for anyone to try. This is why I choose this topic because it is fascinating and also very fun as you do not know what kind of result you might get after combining different types of metal.

3) A metallic bond is actually some what similar to a covalent bond except that the electrons are able to circulate between all the atoms. This accounts for metals ability to conduct electricity and other propeties like their ductility.

Electrolysis By Zachary Ang

In chemistry and manufacturing, electrolysis is a method of using an electric current to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially highly important as a stage in the separation of elements from naturally-occurring sources such as ores using an electrolytic cell.

The illustration of electrolysis apparatus that is usually used in school's laboratories.

Overview

Electrolysis is the passage of an electric current through an ionic substance that is either molten or dissolved in a suitable solvent, resulting in chemical reactions at the electrodes and separation of materials.

The main components required to achieve electrolysis are:

• A liquid containing mobile ions - an electrolyte
• An external source of direct electric current
• Two solid rods or plates known as electrodes

The components perform the following roles in the electrolysis process:

• The mobile ions are the carriers of electrical current in the liquid (electrolyte). If the ions are not mobile, as in a solid salt then electrolysis cannot occur.
• The externally supplied direct electric current supplies the energy necessary to create or discharge the ions in the liquid or solution. Electric current is carried by electrons in the external circuit.
• The electrodes provide the physical interface between
  • The electrical circuit providing the energy to achieve the electrolysis
  • The electrolyte containing the ionic materials that are to be separated.

The electrodes must be able to conduct electricity. Electrodes of metal, graphite and semiconductor material are widely used. Choice of suitable electrode depends on:

• Chemical reactivity between the electrode and electrolyte
• Cost of manufacture of the electrode

Ancillary practical components to achieve electrolysis include:

• Vessels to supply, contain and remove the reactants and products
• Electrical circuitry

Process of electrolysis

The key process of electrolysis is the interchange of atoms and ions by the removal or addition of electrons from the external circuit. The required products of electrolysis are in some different physical state from the electrolyte and can be removed by some physical process. For example, in the electrolysis of brine to produce hydrogen and chlorine, the products are gaseous. These gaseous products bubble from the electrolyte and are collected.

A liquid containing mobile ions (electrolyte) is produced by

• Solvation or reaction of an ionic compound with a solvent (such as an acid) to produce mobile ions
• An ionic compound is melted (fused) by heating

An electrical potential is applied across a pair of electrodes immersed in the electrolyte.

Each electrode attracts ions that are of the opposite charge. Positively-charged ions (cations) move towards the electron-providing (negative) cathode, whereas negatively-charged ions (anions) move towards the positive anode.

At the electrodes, electrons are absorbed or released by the atoms and ions. Those atoms that gain or lose electrons to become charged ions pass into the electrolyte. Those ions that gain or lose electrons to become uncharged atoms separate from the electrolyte. The formation of uncharged atoms from ions is called discharging.

The energy required to cause the ions to migrate to the electrodes, and the energy to cause the change in ionic state, is provided by the external source of electrical potential.

Oxidation and reduction at the electrodes

Oxidation of ions or neutral molecules occurs at the anode, and the reduction of ions or neutral molecules occurs at the cathode. For example, it is possible to oxidize ferrous ions to ferric ions at the anode:

Fe2+aq → Fe3+aq + e^–

It is also possible to reduce ferricyanide ions to ferrocyanide ions at the cathode:

Fe(CN)3-6 + e^– → Fe(CN)4-6

Neutral molecules can also react at either electrode. For example: p-Benzoquinone can be reduced to hydroquinone at the cathode:

+ 2 e^– 2 H⁺ →

In the last example, H⁺ ions (hydrogen ions) also take part in the reaction, and are provided by an acid in the solution, or the solvent itself (water, methanol etc). Electrolysis reactions involving H⁺ ions are fairly common in acidic solutions. In alkaline solutions, reactions involving OH^- (hydroxide ions) are common.

The substances oxidised or reduced can also be the solvent (usually water) or the electrodes. It is possible to have electrolysis involving gases.

Energy changes during electrolysis

The amount of electrical energy that must be added equals the change in Gibbs free energy of the reaction plus the losses in the system. The losses can (in theory) be arbitrarily close to zero, so the maximum thermodynamic efficiency equals the enthalpy change divided by the free energy change of the reaction. In most cases, the electric input is larger than the enthalpy change of the reaction, so some energy is released in the form of heat. In some cases, for instance, in the electrolysis of steam into hydrogen and oxygen at high temperature, the opposite is true. Heat is absorbed from the surroundings, and the heating value of the produced hydrogen is higher than the electric input.

Related techniques

The following techniques are related to electrolysis:

• Gel electrophoresis is an electrolysis using a gel solvent. It is used to separate substances, such as DNA strands, based on their electrical charge.
• Electrochemical cells, including the hydrogen fuel cell, utilise differences in Standard electrode potential in order to generate an electrical potential from which useful power can be extracted. Although related via the interaction of ions and electrodes, electrolysis and the operation of electrochemical cells are quite distinct. A chemical cell should not be thought of as performing "electrolysis in reverse".

Faraday's laws of electrolysis

First law of electrolysis

In 1832, Michael Faraday reported that the quantity of elements separated by passing an electrical current through a molten or dissolved salt is proportional to the quantity of electric charge passed through the circuit. This became the basis of the first law of electrolysis:

Second law of electrolysis

Faraday also discovered that the mass of the resulting separated elements is directly proportional to the atomic masses of the elements when an appropriate integral divisor is applied. This provided strong evidence that discrete particles of matter exist as parts of the atoms of elements.

Industrial uses

Hall-Heroult process for producingaluminium

• Production of aluminum, lithium, sodium, potassium, magnesium
• Coulometric techniques can be used to determine the amount of matter transformed during electrolysis by measuring the amount of electricity required to perform the electrolysis
• Production of chlorine and sodium hydroxide
• Production of sodium chlorate and potassium chlorate
• Production of perfluorinated organic compounds such as trifluoroacetic acid
• Production of electrolytic copper as a cathode, from refined copper of lower purity as an anode.

Electrolysis has many other uses:

• Electrometallurgy is the process of reduction of metals from metallic compounds to obtain the pure form of metal using electrolysis. For example, sodium hydroxide in its molten form is separated by electrolysis into sodium and oxygen, both of which have important chemical uses. (Water is produced at the same time.)
• Anodization is an electrolytic process that makes the surface of metals resistant to corrosion. For example, ships are saved from being corroded by oxygen in the water by this process. The process is also used to decorate surfaces.
• A battery works by the reverse process to electrolysis. Humphry Davy found that lithium acts as an electrolyte and provides electrical energy.^{[citation needed]}
• Production of oxygen for spacecraft and nuclear submarines.
• Electroplating is used in layering metals to fortify them. Electroplating is used in many industries for functional or decorative purposes, as in vehicle bodies and nickel coins.
• Production of hydrogen for fuel, using a cheap source of electrical energy.
• Electrolytic Etching of metal surfaces like tools or knives with a permanent mark or logo.

Electrolysis is also used in the cleaning and preservation of old artifacts. Because the process separates the non-metallic particles from the metallic ones, it is very useful for cleaning old coins and even larger objects.

Competing half-reactions in solution electrolysis

Using a cell containing inert platinum electrodes, electrolysis of aqueous solutions of some salts leads to reduction of the cations (e.g. metal deposition with e.g. zinc salts) and oxidation of the anions (e.g. evolution of bromine with bromides). However with salts of some metals (e.g. sodium) hydrogen is evolved at the cathode and for salts containing some anions (e.g. sulfate (SO₄²⁻)) oxygen is evolved at the anode, and in both cases this is due to water being reduced to form hydrogen or oxidised to form oxygen. In principle the voltage required to electrolyse a salt solution can be derived from the standard electrode potential for the reactions at the anode and cathode. The standard electrode potential is directly related to the Gibb's free energy, ΔG, for the reactions at each electrode and refers to an electrode with no current flowing. An extract from the table of standard electrode potentials is shown below.

Half-reaction	E° (V)	Ref.
Na+ + e− Na(s)	-2.71
Zn2+ + 2e− Zn(s)	-0.7618
2H+ + 2e− H2(g)	≡ 0
Br2(aq) + 2e− 2Br−	+1.0873
O2(g) + 4H+ + 4e− 2H2O	+1.23
Cl2(g) + 2e− 2Cl−	+1.36
S2O82– + 2e− 2SO2−4	+2.07

In terms of electrolysis, this table should be interpreted as follows

• oxidised species (often a cation) nearer the top of the table are more difficult to reduce than oxidised species further down. For example it is more difficult to reduce sodium ion to sodium metal than it is to reduce zinc ion to zinc metal.
• reduced species (often an anion) near the bottom of the table are more difficult to oxidise than reduced species higher up. For example it is more difficult to oxidise sulfate anions than it is to oxidise bromide anions.

Using the Nernst equation the electrode potential can be calculated for a specific concentration of ions, temperature and the number of electrons involved. For pure water (pH 7):

• the electrode potential for the reduction producing hydrogen is −0.41 V
• the electrode potential for the oxidation producing oxygen is +0.82 V.

Comparable figures calculated in a similar way, for 1M zinc bromide, ZnBr₂, are −0.76 V for the reduction to Zn metal and +1.10 V for the oxidation producing bromine. The conclusion from these figures is that hydrogen should be produced at the cathode and oxygen at the anode from the electrolysis of water which is at variance with the experimental observation that zinc metal is deposited and bromine is produced. The explanation is that these calculated potentials only indicate the thermodynamically preferred reaction. In practice many other factors have to be taken into account such as the kinetics of some of the reaction steps involved. These factors together mean that a higher potential is required for the reduction and oxidation of water than predicted, and these are termed overpotentials. Experimentally it is known that overpotentials depend on the design of the cell and the nature of the electrodes.

For the electrolysis of neutral (pH 7) sodium chloride, the reduction of sodium ion is thermodynamically very difficult and water is reduced evolving hydrogen leaving hydroxide ions in solution. At the anode the oxidation of chlorine is observed rather than the oxidation of water since the overpotential for the oxidation of chloride to chlorine is lower than the overpotential for the oxidation of water to oxygen. The hydroxide ions and dissolved chlorine gas react further to form hypochlorous acid. The aqueous solutions resulting from this process is calledelectrolyzed water and is used as a disinfectant and cleaning agent.

Electrolysis of water

One important use of electrolysis of water is to produce hydrogen.

2 H₂O(l) → 2 H₂(g) + O₂(g); E₀ = +1.229 V

Hydrogen can be used as a fuel for powering internal combustion engines by combustion or electric motors via hydrogen fuel cells . This has been suggested as one approach to shift economies of the world from the current state of almost complete dependence upon hydrocarbons for energy

The energy efficiency of water electrolysis varies widely. The efficiency is a measure of what fraction of electrical energy used is actually contained within the hydrogen. Some of the electrical energy is converted to heat, a useless byproduct. Some reports quote efficiencies between 50% and 70% This efficiency is based on the Lower Heating Value of Hydrogen. The Lower Heating Value of Hydrogen is total thermal energy released when hydrogen is combusted minus the latent heat of vaporisation of the water. This does not represent the total amount of energy within the hydrogen, hence the efficiency is lower than a more strict definition. Other reports quote the theoretical maximum efficiency of electrolysis as being between 80% and 94%.. The theoretical maximum considers the total amount of energy absorbed by both the hydrogen and oxygen. These values refer only to the efficiency of converting electrical energy into hydrogen's chemical energy. The energy lost in generating the electricity is not included. For instance, when considering a power plant that converts the heat of nuclear reactions into hydrogen via electrolysis, the total efficiency is more likely to be between 25% and 40%.

NREL found that a kilogram of hydrogen (roughly equivalent to a gallon of gasoline) could be produced by wind powered electrolysis for between $5.55 in the near term and $2.27 in the long term.

About four percent of hydrogen gas produced worldwide is created by electrolysis, and normally used onsite. Hydrogen is used for the creation of ammonia for fertilizer via the Haber process, and converting heavy petroleum sources to lighter fractions via hydrocracking.