Alcohol

This reaction is exothermic, as heat is given out. This is because the

amount reactant energy is more than the product energy the difference

between this is ?H, therefore some energy has been given out in the

form of heat.The energy is given out when forming the bonds between

the new water and carbon dioxide molecules. This can be shown in an

energy level diagram: Reaction co-ordinate ?H is the heat content,

which is the enthalpy, which is negative in exothermic reactions as

the diagram shows that energy is 'lost' as heat. Enthalpy is defined

as the energy of reaction, or the heat energy associated with a

chemical change. Chemical Principles By Master & Slowinski says that

"For any reaction carried out directly at a constant pressure, the

heat flow is exactly equal to the difference between enthalpy of

products and that of the reactants", or: Qp = Hp - Hr = ?H Where Qp is

the heat flow at constant pressure, Hp is heat energy of products, and

Hr is the heat energy of the reactants.

To measure ?H given off, we must use this energy to heat something,

this will be water. This is assuming that all the heat produced by

combustion of fuel (?H) will equal the amount of heat absorbed by the

water (q). So I will measure the amount of energy required to do so.

This can be worked out by useing the formula: q = mass X specific heat

capacity X temperature rise 1000 Where q is the quantity of heat. The

specific heat capacity is the amount of energy required to heat the

substance, and is calculated using the formula q = MC?, where q is the

enthalpy, is