Chemistry > Thermodynamics and Thermochemistry > 4.0 Work $(W)$
Thermodynamics and Thermochemistry
1.0 Introduction to Thermodynamics
1.1 Importance of Thermodynamics
1.2 Limitations of Thermodynamics
1.3 Some Basic Terms of Thermodynamics
2.0 Thermodynamic Processes
2.1 Some other important relations of adiabatic process
2.2 Reversible and Irreversible Processes
2.3 Polytropic Process
3.0 Heat $(Q)$
4.0 Work $(W)$
5.0 Internal Energy
6.0 Zeroth Law of Thermodynamic
7.0 First Law of Thermodynamics
8.0 Heat Capacity
9.0 Enthalpy $(H)$ or Heat Content
10.0 Significance of $?H$ and $?E$
11.0 Relationship Between $?H$ and $?E$
12.0 Standard Enthalpy of Reaction
12.1 Molar Enthalpy of Fusion $\left( {\Delta {H_{fus}}} \right)$
12.2 Molar Enthalpy of Vaporisation $(\Delta {H_{vap}})$
12.3 Enthalpy of Sublimation $\left( {\Delta {H_{sub}}} \right)$
12.4 Enthalpy of Formation
12.5 Enthalpy of Combustion $\left( {\Delta {H_c}} \right)$
12.6 Enthalpy of Neutralization $\left( {\Delta {H_{neu}}} \right)$
12.7 Enthalpy of Solution $\left( {\Delta {H_{sol}}} \right)$
13.0 Law of Thermodynamics
14.0 Bond Energy or Bond Enthalpies
15.0 Second Law of Thermodynamic
16.0 Entropy (S)
16.1 Some Important points Related to Entropy
16.2 Entropy Change in Various Thermodynamic Process
16.3 Entropy Change in Phase Transformation
17.0 Spontaneous Processes
18.0 Free Energy (G)
19.0 Enthalpy, Entropy, Free Energy Changes and The Nature of Process
20.0 Standard Free Energy Change
21.0 Coupled Reactions
22.0 Third Law of Thermodynamic
22.1 Third Law of Thermodynamics, Entropy ? Temperature
22.2 Limitations of Third Law of Thermodynamics
23.0 Important Facts
4.1 Pressure- volume work
1.2 Limitations of Thermodynamics
1.3 Some Basic Terms of Thermodynamics
2.2 Reversible and Irreversible Processes
2.3 Polytropic Process
12.2 Molar Enthalpy of Vaporisation $(\Delta {H_{vap}})$
12.3 Enthalpy of Sublimation $\left( {\Delta {H_{sub}}} \right)$
12.4 Enthalpy of Formation
12.5 Enthalpy of Combustion $\left( {\Delta {H_c}} \right)$
12.6 Enthalpy of Neutralization $\left( {\Delta {H_{neu}}} \right)$
12.7 Enthalpy of Solution $\left( {\Delta {H_{sol}}} \right)$
16.2 Entropy Change in Various Thermodynamic Process
16.3 Entropy Change in Phase Transformation
22.2 Limitations of Third Law of Thermodynamics
Consider a cylinder fitted with a frictionless and weightless piston having an area of cross section A. Let the pressure acting on the piston is P(external pressure), which is slightly less than the internal pressure of the gas. Suppose the gas expands a little and piston is pushed out a small distance dx. The work done by the gas on the piston is
$dW = force × distance$
$(? F = P.A )$
$dW=$ Pressure $×$ Area $×$ Distance
$dW= P.A. dx 1$
$? A.dx = dV$
$dW = P.dV$
If the volume of gas changes from ${V_1}$ to ${V_2}$ then total work is done $W$ will be given by
$W = \int\limits_{{v_1}}^{{v_2}} {P.dV} $
If the external pressure $P$ against which the gas expands remains almost constant throughout the process then
$W = P\int\limits_{{v_1}}^{{v_2}} {dV = P\left( {{V_2} - {V_1}} \right)} $
$W= P\Delta V$
According to latest SI convention
(i) Work is taken as $(–)$ ve when work is done by the system on the surrounding as in the expansion of gas
$\Delta W = - P\Delta V$
(ii) Work is taken as $(+)$ ve when work is done on the system as in the contraction of gas,
$\Delta W = P\Delta V$
