Task 9 (individual reflection)
In this 3 week of e-learning, I have to agree that the task is a bit demanding yet it is interesting. The lesson is integrated with IT software (which I like very much!) from free accessible internet and group based assignment. It promotes social interaction and critical thinking about the topic of chemistry. The most important thing is it induces a learning environment with a lot of freedom. Most of the lesson is done at home (not classroom based) and own time own target. All these will not be able to obtain during a normal base classroom. In addition, I find out that the normal teacher and student barrier in classroom disappear in the e learning environment. Besides widening my knowledge on Chemistry, I am also learning more about IT which can put to use in my future endeavor.
-Melvin
Member of Group 2
Thursday, April 1, 2010
Tuesday, March 30, 2010
Friday, March 26, 2010
Queries Answer for lesson 1
Group 1's queries
1) From the video, decomposition and combustion both produce carbon dioxide. Why is both reaction classified differently?
Ans: Combustion must involve the reaction of oxygen with the reactant while decomposition do not.
2) From our past knowledge, for combustion, heat is given out. But why is it still consider as combustion when no heat is given out?
Ans: Combustion can be classified as endothermic (heat absorbed) and exothermic (heat releaased). As long as oxygen is taken in, no matter heat is taken in or given out, the reaction is considered as combustion.
Group 4's queries
3) What is the key difference between combustion and double replacement reaction?
Ans: Both reaction involved the combination of two molecule and separation of two molecule after the reaction. However oxygen is required to be the reactant for combustion whereas double replacement reaction can be any two molecules.
Group 5's queries
2) How can we differentiate between complete combustion and incomplete combustion?
Ans: Both reaction require oxygen to be taken in during the process. However, carbon dioxide (CO2) is produced for complete combustion where as carbon monoxide (CO) and soot (C) is given out for incomplete combustion.
1) From the video, decomposition and combustion both produce carbon dioxide. Why is both reaction classified differently?
Ans: Combustion must involve the reaction of oxygen with the reactant while decomposition do not.
2) From our past knowledge, for combustion, heat is given out. But why is it still consider as combustion when no heat is given out?
Ans: Combustion can be classified as endothermic (heat absorbed) and exothermic (heat releaased). As long as oxygen is taken in, no matter heat is taken in or given out, the reaction is considered as combustion.
Group 4's queries
3) What is the key difference between combustion and double replacement reaction?
Ans: Both reaction involved the combination of two molecule and separation of two molecule after the reaction. However oxygen is required to be the reactant for combustion whereas double replacement reaction can be any two molecules.
Group 5's queries
2) How can we differentiate between complete combustion and incomplete combustion?
Ans: Both reaction require oxygen to be taken in during the process. However, carbon dioxide (CO2) is produced for complete combustion where as carbon monoxide (CO) and soot (C) is given out for incomplete combustion.
Combustion (Chemistry Reaction)
Combustion
Combustion is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species.
The release of heat can result in the production of light in the form of either glowing or a flame. Fuels of interest often include organic compounds (especially hydrocarbons) in the gas, liquid or solid phase.
In a complete combustion reaction, a compound reacts with an oxidizing element, such as oxygen or fluorine, and the products are compounds of each element in the fuel with the oxidizing element. For example:
CH4 + 2O2 → CO2 + 2H2O + energy
CH2S + 6F2 → CF4 + 2HF + SF6
Incomplete combustion occurs when there isn't enough oxygen to allow the fuel to react completely with the oxygen to produce carbon dioxide and water, and also when the combustion is quenched by a heat sink such as a solid surface or flame trap.
A simpler example can be seen in the combustion of hydrogen and oxygen, which is a commonly used reaction in rocket engines:
2H2 + O2 → 2H2O(g) + heat
The result is water vapor.
Generally, the chemical equation for stoichiometric burning of hydrocarbon in oxygen is
Combustion is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species.
The release of heat can result in the production of light in the form of either glowing or a flame. Fuels of interest often include organic compounds (especially hydrocarbons) in the gas, liquid or solid phase.
In a complete combustion reaction, a compound reacts with an oxidizing element, such as oxygen or fluorine, and the products are compounds of each element in the fuel with the oxidizing element. For example:
CH4 + 2O2 → CO2 + 2H2O + energy
CH2S + 6F2 → CF4 + 2HF + SF6
Incomplete combustion occurs when there isn't enough oxygen to allow the fuel to react completely with the oxygen to produce carbon dioxide and water, and also when the combustion is quenched by a heat sink such as a solid surface or flame trap.
A simpler example can be seen in the combustion of hydrogen and oxygen, which is a commonly used reaction in rocket engines:
2H2 + O2 → 2H2O(g) + heat
The result is water vapor.
Generally, the chemical equation for stoichiometric burning of hydrocarbon in oxygen is
For example, the burning of propane is
Generally, the chemical equation for stoichiometric incomplete combustion of hydrocarbon in oxygen is as follows:
For example, the incomplete combustion of propane is:
The simple word equation for the combustion of a hydrocarbon in oxygen is:
Monday, March 22, 2010
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