Department of Bioorganic and Biological Chemistry. Bioinorganic chemistry

I COURSE

LECTURER: Professor A.D.DZHURAEV

LECTURE 2. THE CHEMICAL THERMODYNAMICS AND

BIOENERGETICS

PURPOSE OF LECTURES:• Give an idea of thermodynamics, noting the

universality of the laws of thermodynamics to the animate and inanimate nature.

• Acquaint with the basic laws of thermodynamics, to give an idea about the systems and their types. Provide insight into the relationship between the processes of metabolism and energy in the body. To familiarize with the laws of thermodynamics, drawing attention to the irreversible processes in the body.

THE LECTURE PURPOSE:

• The notion about laws of the thermodynamics are given, as they universal for alive and not alive nature. Must know, as it is filled up the lost by organism energy in process of vital activity, and what types of energy is act in organism. The breach of the energy exchange is a reason of the row of hard treatment diseases of the person therefore physician must know the mechanism of the transformation different material in energy.

DEALT of questions

• The object and purpose of thermodynamics• The value of the laws of thermodynamics in

medicine• Thermodynamic systems and

thermodynamic parameters• The internal energy• The first law of thermodynamics• Isobaric and isochoric heat effects• Enthalpy

• Chemical Thermodynamics. thermal effects• Hess's Law and its consequences• The second law of thermodynamics• Entropy and Free Energy• Conditions of thermodynamic equilibrium• Spontaneous thermodynamic processes and

conditions of their orientation

DEALT of questions

The subject of thermodynamics

Thermodynamics -- the science of the laws of different types of energy transformation in each other.        Its object of study - thermodynamic systems

Systems and their classification...

• Part of the space arbitrarily limited the interface from the environment is called a system.

•     On the principle of exchange with the environment of the system are:

• Open - exchange of matter and energy and• Closed - only exchanged energy• Isolated - do not share neither substance nor energy

Thermodynamic system and its internal energy

• Any system characterized by the so-called state of thermodynamic parameters - mass, volume, pressure, temperature swarm, composition, specific heat, and internal energy.

• The internal energy of the system - a combination of all kinds of energy in the system.

U = Ukinetic + Upotential + Uвн Uвн = U2 - U1

The first law of thermodynamics• In any process of energy does not disappear

and does not appear out of nothing, it just changes from one form to another in equivalent amounts.

•   The first law of thermodynamics, applied to the activity of a living organism

• The chemical energy of metabolism is transformed into other forms of energy and allows the flow of the vital processes in the body.

The mathematical expression of the first law of thermodynamics

U = Q – A or Q = U + AWhere: Q – the amount of heat U – Changing the internal energy::               A - amount of work is done under the

effect of external forces

Chemical Thermodynamics• Section thermodynamics studies of energy conversion

in chemical process called chemical thermodynamics• Processes occur with heat are called exothermic

processes occur with the absorption of heat are called endothermic

• The amount of heat absorbed or released in the course of chemical reactions called the heat of reaction.

Hess's Law "The thermal effect of the chemical

reaction (enthalpy) depends on the type and condition of the starting materials and reaction products and not on the path of transition from the initial to the final “

Q = Q1 + Q2 = Q3 + Q4 + Q5

Q1 Q2

Q Q3 Q5

Q4

Hess's Law

Pb + S + 2O2 = PbSO4 + 919,7I. Pb + S = PbS + 94,5II. PbS + 2O2 = PbSO4 + 825,2

919,7

The thermal effect of the isothermal process

An isothermal process t = const, heat is transferred from one body to another without changing the temperature, than,

Q т = рV

Thermal effect isochoric process

Isochoric process when the volume is constant, than, V = const

With unchanged quantities: V = 0 when work is not done: рV = 0In such conditions, according to the first law of

thermodynamics, the total amount of heat supplied to the system spent to increase the internal energy:

QV = U

Thermal effect of isobaric processWhen the process of isobaric pressure is constant: P =

const    For such a state of expression for the first law of

thermodynamics Q = U + р V is rewritten as follows:

QP = U2 -U1 + р(V2 -V1) = U2 - U1 + рV2 -рV1

QP = (U2 + рV2) - (U1 - рV1)The thermal effect at constant pressure is called the

enthalpy of the system and is denoted by H:U + рV = H

then: QP = H2 - H1 = H Heat spent to increase its enthalpy

The second law of thermodynamics

The heat is not transferred spontaneously from a cold to a hot body, ie If any form of energy can be converted into heat in the case of the reverse transformation of heat into any energy, complete conversion can not be.

Entropy

Entropy is the ratio of the heat of reaction to the absolute temperature, S = Q \ T

        Logarithmic value of the thermodynamic probability of a system is called entropy:S = k lgW

Here: S - entropy - disorder in the function of the

system;                 k - Boltzmann constant                W - thermodynamic probability

Entropy. Standard entropy

The entropy determined at standard conditions (T = 2980K,

    p = 101.3 kPa) is called the absolute value or the standard entropy and designated S0 298

(∆S0 298) = ∑( S0 298)product - ∑( S0 298) outgoing materials

Example calculation of standard entropy

С( ) + СО2 (g) = 2СО(g)5,7 213,7 197,5

Standard entropy will be:

S0 298 = 2( S0 298) СО – [( S0 298)С + (S0 298)СО2] = = 2 - 197,5 - ( 5,7 + 213,7) =175,6 joules (mol K)

Gibbs energy.1. Free energy - the energy thatcan be converted into work2. Bound energy - an energy that in the process

can not be converted intojob.

G = H - T * S or ΔG = ΔH - TΔS,         G - Gibbs energy       ΔH - enthalpy factor         TΔS - entropy factor

Parameters calculated for the direction and feasibility of the thermodynamic process:

• ΔG <0 - spontaneous process, a transition of the system from the initial state to the final

•      ΔG = 0 - the system in balance•     ΔG> 0 - a transition from the initial to the final• thermodynamic process: