The Burning of Primary and Secondary Alcohols
Year 11A Chemistry
By Jarrod Ahern
The aim of the investigation was to determine whether primary alcohols use less energy than secondary alcohols for fuel. The hypothesis is if primary alcohols are heated and results are taken, they produce a lesser heat of reaction then secondary alcohols. The method used was to find the average bond energies of three relating primary and secondary alcohols and compare it with the average theoretical values. Hence the primary alcohols produce less energy most of the time and this was tested by using the correct methods.
Pg 1 - Aim
Pg 1-2 - Theory
Pg 2 - Hypothesis
Pg 2-3 - Variables
Pg 3 - Apparatus
Pg 3 - Procedure
Pg 4 - Results
Pg 5-6 - Analysis
Pg 7 - Discussion
Pg 8 - Conclusion
Pg 9 - Appendices
Pg 11 - Bibliography
There are many different purposes for fuel around the world right now. The use of fuels has increased and we are investigating to find the most essential fuels for various things. Using the most effective fuel source is essential. Hence, various primary and secondary alcohols will be tested to see which uses the lesser energy. The investigation is aimed to determine whether primary alcohols use less energy than secondary alcohols for fuel. Theory
An alcohol is referred to as groups of organic chemical compounds. Alcohols occur when a hydroxyl (-OH) functional group replaces one or two of the hydrogen atoms. There are many types of alcohols but they are classified by their structure. Primary, Secondary and Tertiary depending on how many carbons are attached to the OH group. Primary and Secondary structures will be the main focus of this assignment. Primary alcohols are when the carbon atom that carries the –OH group is only attached to one alkyl group. A secondary alcohol is when the OH is directly linked to two of the alkyl groups. The tertiary is the final alcohol group this occurs when the OH molecule is attached to three alkyl groups.
When chemical reactions occur they require energy to break and form bonds which is released in the form of heat. There are two different types of enthalpy reaction, endothermic and exothermic. Endothermic is when a system absorbs the heat and turns cold, and when it produces heat it is known as an exothermic reaction. However, this investigation will only analyse exothermic reactions. Enthalpy cannot be measured directly, it is calculated as the heat added or lost in the reaction which is the change in enthalpy, or H. H shows the difference between the enthalpy at the start of the reaction compared to what it is at the end of the reaction. Hess’s Law is a method used to find enthalpy change within a reaction. Hess's law is the sum of the heats of formation of the products minus the sum of the heats of formation of the reactants is equal to the enthalpy change of the reaction. It is very important as it determines the enthalpy change of a reaction even if it’s not easily measured directly. Combustion is a key factor that is looked at in this report. Combustion is a form of exothermic chemical reaction in which a reaction between two or more chemicals produces heat. For combustion to take place a fuel source and oxygen is needed and this can take
place anywhere in the atmosphere or in a closed system. When an exothermic reaction occurs involving a fuel heat is created, as well as carbon dioxide and water. When a substance is completely broken down and transformed into oxygen and carbon dioxide the combustion is complete but it is almost impossible to accomplish. In this experiment, combustion took place when the alcohols where being burnt. The bonds broke and the fuel completely disappeared and turned into oxygen and carbon dioxide. There wasn’t enough time for the combustion to complete and this would result in soot on the bottom of the test tube.
If primary alcohols are heated and results are taken, they...
Bibliography: Anne Marie Helmenstine (2011) About Chemistry, retrieved August 27 from <http://chemistry.about.com/od/workedchemistryproblems/a/bondenergyexmpl.htm>
Author unknown (2011) Combustion Training, retrieved August 31 from <http://www.e-inst.com/combustion/>
Author Unknown (n.d) Definition of Hess’s Law, retrieved August 23 from http://www.cramster.com/definitions/hesss-law/244
Author Unknown (n.d) Stoichiometric Combustion, retrieved August 23 from http://www.engineeringtoolbox.com/stoichiometric-combustion-d_399.html
Dortmund Data Bank Software & Seperation Technology (2009) HFO (Std. Heat of Formation) Data for Propanol, Retrieved September 6 from <http://onlinelibrary.wiley.com/doi/10.1002/recl.19700891208/abstract>
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