Alcohols are compound that has one or more hydrogen atoms in an alkane which has been replaced by an –OH group (Chem Guide, 2003).The general chemical formula for alcohols is CnH2n+1OH (BBC, 2014).Alcohols are any of a class of organic compounds characterized by one or more hydroxyl (−OH) groups attached to a carbon atom of an alkyl group (hydrocarbon chain) (Encyclopaedia Britannica). Alcohols are split into three different groups known as primary alcohols, secondary alcohols and tertiary alcohols. Primary alcohols are when the carbon with the hydroxyl group is only attached to one alkyl group, secondary alcohols are when the hydroxyl group is attached to two alkyl groups, An alkyl group is a piece of a molecule with the general formula CnH2n+1, where n is some integer. For example, a methyl group (CH3) is a fragment of a methane molecule (CH4); n = 1 in this case (General Chemistry Online, 2010). Tertiary alcohols are the carbon with the hydroxyl group is attached to three other alkyl groups. The heat of reaction is an important factor in the burning of alcohols. The heat of reaction is the change is heat of a chemical reaction that occurs at a constant pressure. It is a unit of measurement that is useful for calculating the amount of energy per mole that is produced in a chemical reaction. ∆H also known as the change in heat or enthalpy is a unit of measurement that is meant to calculate the change in energy of a system when it is too difficult to find the change in internal energy of a system. (UCDAVIS Chem Wiki) This is accomplished by measuring the amount of heat and work that has been exchanged. It is measured in kilojoules per mole (kJ/mol). Bond energies are a measure of the amount of energy needed to break apart one mole of covalently bonded gasses (UCDAVIS Chem wiki 2015). Atoms combine together to create compounds since doing so they gain lower energies that they have as single atoms. Bonds do not break and form spontaneously-an energy change is required. The energy input required to break a bond is known as bond energy. (UCDAVIS Chem wiki 2015). When there is a stronger bond there is a higher bond energy because the stronger the bond the more energy it takes to break the bond, and when there is a larger bond order the bond length is shorter and when there is a shorter bond length meaning there is a superior bond energy. Bond energies can be used to calculate heats of reaction (enthalpy) using the change in heat formula. An example of using bond energies to calculate heats of reactions is shown below; …show more content…
This law is a manifestation that enthalpy is a state function. (UCDAVIS Chem Wiki 2015). The definition of Hess’s Law is that the heat of any ∆H○f for a specific reaction is equals to the sum the heats of reaction for any set of reactions which in sum are equivalent to the overall reaction. (UCDAVIS Chem Wiki 2015) Hess’s Law is mainly due to enthalpy being a state of function, which can calculate the overall change in enthalpy by adding up the changes for each step of the way until the product is made. All the steps have to continue at the exact same temperature and the equations for the single steps must balance out. An example of using Hess’s Law is shown below; (Chem Team,