Title 5_Thermodynamics & Chemical Energetics.docx ✅

PRE-MEDICAL 81 PHYSICAL CHEMISTRY Serial No. MODULE-1 Page No. 1. Some basic concepts of Chemistry 2. Atomic structure 3. Chemical Equilibrium 4. Ionic Equilibrium 5. Thermodynamics & Chemical Energetics 6. Redox reactions 7. Behaviour of Gases 8. Hints and Solutions
PRE-MEDICAL 81 CHEMICAL THERMODYNAMICS AND ENERGETICS S.No. CONTENTS Page No. THERMODYNAMICS 1. Introduction 2. Some important terms 3. Type of thermodynamic process 4. Work and Heat 5. Internal energy 6. Laws of thermodynamics 7. Enthalpy 8. Heat capacity 9. Work done in different process 10. Spontaneous and non-spontaneous process 11. Entropy 12. Gibbs energy ENERGETICS 13. Introduction 14. Heat of reaction 15. Types of heat or reaction 16. Laws of thermochemistry 17. Exercise-I (Conceptual Questions) 18. Exercise-II (Previous Years Questions) 19. Exercise-III (Analytical Questions) 20. Exercise-IV (Assertion & Reason)
PRE-MEDICAL 81 CHEMICAL THEROMODYNAMICS 5.0 INTRODUCTION Thermo (Heat/energy) + Dynamic (Flow/motion) Thermodynamics is the branch of science which deals with the energy changes taking place in all physical and chemical processes but Chemical thermodynamics is the branch of thermodynamic which deals with the study of energy changes taking place in chemical processes. Advantages of thermodynamics : (i) It gives information about various thermodynamic laws. (ii) It helps us to predict whether a given chemical reaction will take place not under the given set of conditions. (iii) It gives information about various energy changes. Limitations of thermodynamics : (i) Thermodynamics deals with the properties like temperature, pressure, volume etc of matter in bulk but doesn’t tell us anything about the individual properties of atoms or molecules. Or Thermodynamics deals with macroscopic models but not with microscopic models. (ii) It tells us whether a given chemical reaction will take place or not under the given set conditions but doesn’t tell us anything about the rate of reaction. 5.1 SOME IMPORTANT TERMS :  System : A system is defined as a specific part of universe or specified portion of the matter which is under experimental investigation.  Surrounding : The rest part of the universe excluding the system is called surrounding. Universe = System + Surrounding  Boundary : Anything which separates system and surrounding is called boundary/ Types of boundary : (i) Boundary can be conducting or non-conducting. (ii) Boundary can be rigid or non-rigid. (iii) Boundary can be real or imaginary. For example : A reaction is carried out in a beaker. The contents of beaker constitute the system, beaker serves as boundary and the anything which is outside the beaker is called surroundings. 5.2 TYPES OF SYSTEM Systems are of 3 types Open system : This type of system can exchange energy as well as matter with the surrounding. The boundary is neither sealed nor insulated. Total mass will not remain constant. Eg. 1. Coffee in open glass. Hot water in open glass. Eg. 2 All living systems, human being, plants, animals. Eg. 3 Classroom, earth
PRE-MEDICAL 81 Closed system : This type of systems can exchange energy, (in the form of heat, work or radiations) but not matter with its surrounding .the boundary is sealed but not insulated. Amount of the system will remain constant. Eg. 1 Coffee in closed vessel. Hot water in closed vessel. Eg. 2 Glowing bulb, tube light. Eg. 3 A satellite in orbit. Isolated system : This type of system are perfectly insulated systems and cannot interact in any way with its surrounding i.e. neither matter nor energy can be exchanged with the surrounding. The boundary is sealed and insulated. Universe can be considered as an isolated system. Eg. 1 Coffee in thermosflask. 5.3 STATE OF THE SYSTEM  Properties which define state of any system are called its state variables or thermodynamic variables or thermodynamic quantities.  The state of the system is defined by their measurable properties like temperature, pressure, volume etc.  If any of these properties change, state of the system is said to be changed. State Function :  Those state variables which depend only upon initial and final state of the system but doesn’t depend upon the path or mechanism followed by the system to achieve final state are called state function.  State functions are denoted by capital letters. Ex. E, H, S, G, T, P , V etc. Path Function :  Properties of the system which depend upon the initial and final state of the system as well as the path or mechanism followed by the system to achieve final state are called path function.  Path functions are denoted by small letters. Eg. Work done (w), heat (q) Thermodynamic properties : (i) Intensive properties : The properties of the system which are independent of matter (size and mass) present in system are called intensive properties. (ii) Extensive properties : The properties of the system which are dependent of matter (size and mass) present in system are called extensive properties. Extensive Properties Intensive Properties Volume (V) Number of moles (n) Mass (m) Gibb’s Energy (G) Entropy (S) Enthalpy (H) Molar volume (V m ) Density (d) Gibb’s energy per mole (G m ) Specific heat Pressure (P) Temperature (T)