🗊Презентация Thermodynamics

Plan Basic terms and concepts. The first law of thermodynamics. Enthalpy. Thermochemical equations. Thermochemistry. Caloric content of food. Calorimetry. Entropy. Second law of thermodynamics. Free energy of system and free energy changes. Gibbs’s energy. Criterion of a spontaneity of chemical processes.

Basic terms and concepts

THE SUBJECT OF THERMODYNAMICS Energy is the capacity of a physical system to perform work. Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, electrical, or other forms.

THE SUBJECT OF THERMODYNAMICS

THE SUBJECT OF THERMODYNAMICS

Work is done when a force applied to some object moves the object. For example, lifting a heavy box is work. Work is the  product of force and displacement. A = Fx A force is that which causes a change in the motion of a body that is free to move.

Heat (Q) describes energy in transit from a warmer body to a cooler body. The inernal energy (U) of a substance is total energy the parts forming the substance. It consist of the kinetic and potential energies of the particles. The kinetic energy is energy of motion, objects in motion. The potential energy is stored energy. It is due to forces of attraction and repulsion acting between the particles.

Generally in chemistry is not required to know the absolute value of internal energy . Most important to know value of change of internal energy in chemical processes. If the internal energy of a system of a system in the initial state is U1 and in the final state U2, then the change of internal energy ΔU may be given by: ΔU= U2- U1 Similarly in chemical reaction, Ur is the internal energy of the reactants and Up is the internal energy of products, then the change of internal energy ΔU: ΔU= Up- Ur.

Thermodynamics Thermodynamics is the branch of physical science that studies all forms of energy and their mutual transformations. Thermodynamics studies: 1) energy transitions from one form to another, from one part to another system; 2) energy effects accompanying the various processes and their dependence on the process conditions; 3) opportunity, direction and limits the flow of spontaneous flow of the processes themselves. Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions within the confines of the laws of thermodynamics.

Thermodynamics allows you to: 1) calculate the thermal effects of different processes; 2) predict whether the process is possible; 3) specify the conditions under which it will occur; 4) consider the conditions of chemical and phase equilibria; 5) form an idea of ​​the energy balance of the body

Terms and concepts System - a collection of physical objects , separated from the environment. Environment - the rest of the space. Isolated system is a system which neither can exchange mass nor energy with the surrounding. Closed system is a system which can exchange energy but not mass with surroundings. Open system is a system which can exchange matter as well as energy with the surroundings. Homogeneous system - all of the components are in a single phase and no interfaces , Heterogeneous system - consisting of several phases.  Phase - the part of the system with the same chemical and thermodynamic properties , separated by the interface . Energy - a quantitative measure of a certain kind of motion.

Application of thermodynamics to biological matter Bioenergy - section thermodynamics studying biosystems. Bioenergy - section of biochemistry, studying energetic processes in the cell.

Thermochemistry

Thermodynamic parameters: extensive and intensive. If the system changes its parameters, then it takes a thermodynamic process. Thermodynamic functions of condition - functions depending on the state of the system and not by the way and the manner in which this state is reached. This is: internal energy (U), enthalpy (H), entropy (S) Gibbs free energy (G) Helmholtz free energy (F)

Types of processes Isotermal process is a process in which temperature remains constant. Isobaric process is a process in which preassure remains constant. Isochoric process is a process in which volume remains constant.

Reversible process is a process that can be reversed by means of infinitesimal changes in some property of the system without loss or dissipation of energy, and can be reversed without causing change in the surroundings. The infinitesimal changes can be in temperature, preassure, etc. Irreversible process is a process which is not reversible. Spontaneous process is a process, which under particular conditions occurs by itself without extraneous source of energy.

Zero law of thermodynamics If each of the two thermodynamic system is in thermal equilibrium with a third, they are in thermal equilibrium with each other.

1st law of thermodynamics

1st law of thermodynamics

1st law of thermodynamics

1st law of thermodynamics

1st law of thermodynamics

In an isochoric process the heat of a reaction is equal to external energy change ΔU: Qv=ΔU In isobaric process the heat is equal to a change of system’s enthalpy ΔH: Qp= ΔH

The positive value of enthalpy change (ΔH>0) corresponds to enthalpy increase or to heat adsorbtion by a system (an endothermic process). The negative value of enthalpy change (ΔH<0) corresponds to enthalpy decrease or to heate release by a system (an exothermic process).

Nature of the thermal effects of chemical reactions. Thermochemical equations.

Nature of the thermal effects of chemical reactions. Thermochemical equations.

Hess's Law

Hess's Law

Hess's Law

Hess's Law

Research of thermochemical calculations for the energy performance of biochemical processes

The human requirement for energy during the 24 h At easy work at sitting state (office managers) is 8400-11700 kJ. At medium and hard work (doctors, postmen, students) is 12500-15100 kJ. At hard physical labor (steel-maker, carpenter, etc.) is 16700-20900 kJ. At special hard labor (sportsmen) is till 30100 kJ.

Research of thermochemical calculations for the energy performance of biochemical processes

CARBOHYDRATES C6H12O6 + 6O2(g) = 6CO2(g) + 6H2O(l) ΔHo=-2816 kJ

FATS 2C57H110O6(s) + 163O2 → 114CO2+110H2O (l) ΔHo=-75520 kJ.

Table 1. Energy value of the food

2nd law of thermodynamics

Entropy Entropy is the property of a system which measures the degree of disorder or randomness in the system.

2nd law of thermodynamics 3) In isolated systems, processes occur spontaneously on condition of entropy increase. 4) In other words: for a spontaneous processes in an isolated system, the change in entropy is positive. ΔS>0.

2nd law of thermodynamics

ΔS= S2-S1

2nd law of thermodynamics

2nd law of thermodynamics

2nd law of thermodynamics

Third law of thermodynamics

2nd law of thermodynamics

2nd law of thermodynamics

Free energy of system and free energy changes.The Gibbs’s equation

Isobaric-isothermal potential or Gibbs energy.

ΔG<0 the process is possible, occurs spontaneously; ΔG>0 the process is impossible, the reverse process occurs spontaneously; ΔG=0 the system is an equilibrium state.

Table 2. Spontaniety of chemical processes

F – Helmholtz energy   (isochoric - isothermal potential) F – Helmholtz energy   (isochoric - isothermal potential) ΔF°=∆U°-T∆S°

Application of the laws of thermodynamics to living systems. Application of the laws of thermodynamics to living systems. Heat released from the body, heat is found by counting the oxidation of substances, i.e. I law applies to life processes . It was long thought that the II law of thermodynamics does not apply to living systems . Must be considered: Biological systems are exchanged with the environment of energy and mass . Processes in living organisms ultimately irreversible. Living systems are not in equilibrium. All biological systems are heterogeneous , multiphase . In a living organism (open system) instead of thermodynamic equilibrium steady state occurs , which is characterized not by equality of forward and reverse processes, and the constancy of the chemical changes and tap metabolites.