Question

TRODUCTION Chemical processes occur spontaneously when they lower the free energy of the system. The free energy at constant temperature and ressure is the Gibbs free energy, AG, which is defined as follows: AG = AH - TAS where AG is the change in free energy of the system, AH is the change in enthalpy of the system and AS is the change in entropy of the system AG, the change in free energy, must be less than zero for a spontaneous process. This follows from the definition of a spontaneous process, it lowers the energy of the system. Free energy, given the symbol G in honor of the American chemist, J. Willard Gibbs, is the energy available from a spontaneous process to do work. For a nonspontaneous process, it is the amount of energy that must be supplied to cause the process to occur. AH the enthalpy change, is the amount of heat energy absorbed by a process that occurs at constant pressure (-AH is the heat given of) AH is often proportional to AT, the temperature change caused by the process. The proportionality constant between AH and AT IS called the specific heat (s). The specific heat is a property of the substance being heated or cooled. For example, the specific heat of water is 4.18 J/g °C) meaning that 4.18 joules of heat energy are required to raise the temperature of 1 gram of water by 1.0°C Not all processes that involve a change in enthalpy are accompanied by a change in temperature. Phase changes, eg melting, boiling. and sublimation all absorb heat. However, the substance undergoing the phase change maintains a constant temperature. All the energy supplied to the substance is consumed in the phase change Processes that give off heat energy (AHO) are exothermic Combustion is obviously an exothermic chemical reaction Condensation of steam to liquid water is also exothermic although water maintains a constant temperature during the process Processes that absorb heal energy (AH> oy are endothermic sweat, liquid water that evaporates from your skin cools you by absorbing heat from your body As the change in entrany road to the number of

Answer 1

Sources of Error	Impact on T	Impact on q	Impact on ΔH
The accuracy of the thermometer used.	Major difference while change in temperature recording. ΔT = Tf - Ti	Heat evolved or absorbed = q = m s ΔT	ΔH = q (reactant) + q (product). Cnahge in value of ΔH is may be very large as in final calculation allHeat evolved or absorbed in exothermic & endothermic reactions may cause percentage error.
The Accuracy in Dilution of solutions.	The specific heat of a substance is the amount of heat needed to increase the temperature of 1 gram of it by 1 K (which is the same as 1°C).	For pure water, the specific heat is = s = 4.18 J g-1 K-1. It means that it needs 4.18 joules to increase the temperature of 1 gram of water by 1 K (or 1°C). As the concentration changes value for S changes :                                            q = m s ΔT 1M , s = 3.8 J/g deg C 2M , s = 3.5 J/g deg C 3M , s = 3.3 J/g deg C 4M , s = 3.0 J/g deg C 5M , s = 2.9 J/g deg C pure acid , s =   1.41 J/g deg C	ΔH = q (reactant) + q (product). Cnahge in value of ΔH is may be very large as in final calculation allHeat evolved or absorbed in exothermic & endothermic reactions may cause percentage error.
Ignoring enthalpy change due to Equipments used.	No impact	One or more Heat evolved or absorbed value is added in final step.	ΔH = q (reactant) + q (product) + q (Calorimeter/Alumminium stirrer/thermometer in J/g degree celcius).                           Change in value of ΔH is may be very large as in final calculation allHeat evolved or absorbed in exothermic & endothermic reactions may cause percentage error.