The fire triangle, for example, is basic chemistry. Let's look. At the points of the triangle are heat or ignition source, fuel and air (or oxygen). Remove or isolate any one and combustion cannot continue. When air (oxygen) is in contact with combustible material (fuel) at a high enough temperature, a fire begins.
Helium is good for overhead, because it is lighter and thus flows upward. Argon allows easier arc starting and a smoother, more stable arc than helium does. Actually, argon pretty much is the most widely used shielding gas nowadays. TIG uses a tungsten electrode that is nonconsumable. In other words it does not burn up like an electrode in stick welding or the wire in metal inert gas (MIG) welding does.
Energetics Aim: To measure the energy released from the complete combustion of a known mass of alcohol or paraffin wax, to heat water. Hypothesis: The combustion of alcohols is exothermic. In this experiment the energy is released from burning a known mass of alcohol in order to heat a known amount of water. A comparison of various alcohols and paraffin wax (methanol, ethanol, propanol, butanol, octanol and candle) as fuels can be made by calculating the quantity of energy transferred to the water. In this experiment, the amount of energy (heat) involved in a chemical change will be determined.
C1.4.3 Hydrocarbon fuels Additional guidance: a) Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur. The gases released into the atmosphere when a fuel burns may include carbon dioxide, water (vapour), carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles (particulates) may also be released. Candidates should be able to relate products of combustion to the elements present in compounds in the fuel and to the extent of combustion (whether complete or partial). No details of how the oxides of nitrogen are formed are required, other than the fact that they are formed at high temperatures.
A) Hydrogen bonds are strong enough to confer structural stability, for example in DNA. B) Hydrogen bonds are weak enough to be easily broken (weaker than covalent bonds). C) They contribute to the water solubility of many macromolecules. D) All of the above Answer: D Page Ref: Section 5 27) London dispersion forces are attractive forces that arise due to A) infinitesimal dipoles generated by the constant random motion of electrons. B) permanent dipoles of molecules containing covalent bonds between atoms of very different electronegativities.
* Explain the air plasma cutting procedure. * List the advantage and disadvantages of using a air plasma cutting torch 3.0 INTRODUCTIONS Plasma is an ionized gas that conducts electricity. Plasma is created by adding energy to an electrically neutral gas. In this case, the gas is compressed air and the energy is electricity. The more electrical energy added, the hotter the plasma arc becomes.
1) shows this covalent bond. Now let's look at ethanol’s molecule is quite simple and only contains 9 atoms, ‘Eth’ meaning two carbon atoms and ‘ol’ mean it had an ‘OH’ or hydroxyl group, thus creating the chemical formulae of CH3CH2OH or ethanol for short. It’s also a clear colourless liquid like water but instead of being scentless, it has a pleasant smell. The combustion of ethanol or when it is alit on fire with high heat energy, it releases a pale blue, non-luminous flame which has the potential to release great amounts of energy. Ethanol has a molecular mass of two carbon, one
Introduction Nucelophilic substitutions are chemical reactions in which an electron rich nucleophile attacks the electron poor electrophile1. There are two classes of nucelophilic reactions – SN1, and SN2. The SN1 reaction is a 2 step, uni-molecular reaction, which is independent of the nucleophile. It requires a highly substituted electrophile since there is a formation of a carbocation in its rate determining step, good polar protic solvents which stabilize the carbocation and a good leaving group1. On the other hand, a SN2 reaction is a concerted, bimolecular reaction which has one slow, transition state1.
Fluorine is a corrosive pale yellow gas. It is highly reactive, participating in reactions with virtually all-organic and inorganic substances. Fluorine is the most electronegative element. Metals, glass, ceramics, carbon, and water will burn with a bright flame in fluorine. It is possible that fluorine can substitute for hydrogen in organic reactions.
Heat Capacity... The Heat Capacity itself is extensive (scales with the size of system), but we can think of making this quantity intensive (making it an intrinsic property of the material) by defining related quantities: the Molar Heat Capacity is defined as the Heat Capacity of a homogeneous pure compound (or element) divided by the the number of moles of that compound (or element) the Specific Heat is defined as the Heat Cpacity of a homogeneous sample divided by its mass. The Heat Capacity of any substance is positive. The Heat Capacity is discontinuous at phase transitions. For a gas, the Heat capacity depends on how one does the heating.