Question

We did an experiment called enthalpy of neutralization

Can you write a 400 words paragraph about: i nternal energy and enthalpy, the First Law of Thermodynamics, energy effects of the reaction. Hess's Law, calorimetry, heat capacity of the system.

Thank you so much!!!!!

Answer 1

Internal energy can be defined in a simpler manner as the total energy possessed by the system. IT includes energy on a microscopic scale , and is the sum of all the microscopic energies such as,

• translational kinectic energy
• vibrational and rotational energy
• potential energy from intermolecular forces   

It is represented by "U".

Another term which deals with energy is Enthalpy(H) - which is defined as the property of the system , equal to the sum of its internal energy and product of the pressure(P) and volume(V) of the system.

Enthalpy = internal energy (U) + P*V

It is not practically possible to evaluate the value of 'H' and therefore value of enthalpy change is measured for a reaction , dH.

The first law of thermodynamics is a special case of law of conversation of energy. IT states that change in internal energy of a system is equal to the heat added to the system subtracted the work done by the system.Thus there is an exchange of energy within the system and the surrounding.It can be expressed by the following equation ,            ,where , Q= HEAT added ;      W=work done by the system

Hess's law -THis law is used to find the total enthalpy change of a chemical reaction. According to this law , enthalpy change of a chemical reaction is equal to the sum of enthalpy chanhge of each indivisual reaction. Thus we can say that if 'A' reacts to form product 'B' , it doesn't matter how many steps are involved to form the product , but the total enthalpy change will be the same.

Calorimetry- It involves various methods used to find the heat change during a reaction.The fundamental unit of measurement is joule or calorie. It is performed with a calorimetre.

Heat capacity of a system- IT is defined as the amount of heat required to raise or increase the temperature of a system by one degree celsius or kelvin .To help in the analysis of systems , molar heat capacity or specific heat capacity is used.