chemistry-class-11-unit-06-chapter-07-chemical-thermodynamics-l-7-8-txdhyo9xvqc

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> Enthalpy </primary>
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- $\Delta_r H=$ total enthalpy of the product - total enthalpy of reactants
- $H_R=$ total enthalpy of reactants
- $H_p=$ total enthalpy or products
- At temp T
- $\Delta r H^0=\sum a_i H_m^0$ (Products) -$\sum b_i H_m^0$ (reactants)
- $\Delta r H^0=\sum a_i \Delta_f H^{\circ}$ (Products) -$\sum b_i \Delta_f H^{\circ}$ (reactants)

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<footer style = "font-size: 18px">Recap $\rightarrow$ Recap $\rightarrow$ <span style = "color:blue"> Enthalpy </span> $\rightarrow$ Enthalpy $\rightarrow$ First law of thermodynamics </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> Enthalpy </primary>
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- $\Delta_r H^\circ = \sum \text{bond enthalpies (reactants)} - \sum \text{bond enthalpies (products)}$(gaseous reactions)
- $\Delta_f H^\circ (T)$, $\Delta_{\text {trs }} H^0(T)$
- $\Delta_{\text {fus }} H^{\circ}(T)$, $\Delta_{\text {vap }} H^{\circ}(T)$
- $\Delta_{\text {sub }} H^{\circ}(T)$, $\Delta_C H^{\circ}(T)$
- $\Delta_a H^{\circ}(T)$,$\Delta_{\text {Sub }} H^{\circ}(T)$
- $\Delta_r H^{\circ} \text { (ionization enthelphy) }$ and $\Delta_{r H^{\circ}} \text { (electron gain)}$
- These all are intensive quantities
- Thermochemical equation, Hess's law ,[Born - Haber cycle]
- $\Delta H$ is a state function it does not depend on the path

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<footer style = "font-size: 18px">Recap $\rightarrow$ Enthalpy $\rightarrow$ <span style = "color:blue"> Enthalpy </span> $\rightarrow$ First law of thermodynamics $\rightarrow$ First law of thermodynamics </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> First law of thermodynamics </primary>
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- 1st law - When one form of energy is converted to another, the total energy is conserved
- $\Delta v=0$ isolated
- $\Delta u=q+w$ closed system 
- $q(\text { system })=-10J$
- $q(\text { surrounding })=+10J$
- $q(\text { total})=0J$
- Does not say
- Wheather the energy transfer will happen?
- which direction?
- How long?
- How fast? $\Rightarrow$ not part of thermodynamics , it is a part of kinetics.

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<footer style = "font-size: 18px">Enthalpy $\rightarrow$ Enthalpy $\rightarrow$ <span style = "color:blue"> First law of thermodynamics </span> $\rightarrow$ First law of thermodynamics $\rightarrow$ Spontaneous and non-spontaneous  process </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> First law of thermodynamics </primary>
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- We know some processes happens spontaneously
- Spreading of perfume
- Gas expand into vaccum
- Hot object in a surrounding which has lower temperature , then the object will cool down
- A weight falls from a height
- On ignition - a fuel burns spontaneously
- Spontaneous processes are irreversible processes

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<footer style = "font-size: 18px">Enthalpy $\rightarrow$ First law of thermodynamics $\rightarrow$ <span style = "color:blue"> First law of thermodynamics </span> $\rightarrow$ Spontaneous and non-spontaneous  process $\rightarrow$ Criteria for spontaneous processes </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> Spontaneous and non-spontaneous  process </primary>
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- Spontaneous process means that the process has a tendency/potential to occur without any assistance from extrenal
agency
- work have  to be done to bring it about

- Non - spontaneous  process-will not happen without any  assistance from external energy
- Spontaneous process is an irreversible process which can only be reversed  only by doing work
- Reverse - non-spontaneous process

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<footer style = "font-size: 18px">First law of thermodynamics $\rightarrow$ First law of thermodynamics $\rightarrow$ <span style = "color:blue"> Spontaneous and non-spontaneous  process </span> $\rightarrow$ Criteria for spontaneous processes $\rightarrow$ Criteria for spontaneous processes </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> Criteria for spontaneous processes </primary>
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- Energy decreases
- $\frac{1}{2} N_2(g)+\frac{3}{2} H_2(g) \rightarrow NH_3(g)$
- $\Delta r_H^{\circ}=-46.1 \mathrm{~kJ} \mathrm{mol}^{-1}$
- Decrease in energy can not be considered for spontaneity

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<footer style = "font-size: 18px">First law of thermodynamics $\rightarrow$ Spontaneous and non-spontaneous  process $\rightarrow$ <span style = "color:blue"> Criteria for spontaneous processes </span> $\rightarrow$ Criteria for spontaneous processes $\rightarrow$ 2nd law thermodynamics </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> Criteria for spontaneous processes </primary>
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- Mixing of ideal gases $\Rightarrow$  spontaneous

- $\frac{1}{2} \mathrm{N}_2(\mathrm{g})+\mathrm{O}_2(g) \rightarrow \mathrm{NO}_2(g)$

- $\Delta rH^\circ = +33.2 \, \mathrm{kJ \, mol^{-1}}$

- What is the criteria for Spontaneity? 
- matter / energy is getting dispersed 
- system + Surroundings $\rightarrow$ together is more random 
-  Natural tendency is to disperse/randomise/ become disordered

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<footer style = "font-size: 18px">Spontaneous and non-spontaneous  process $\rightarrow$ Criteria for spontaneous processes $\rightarrow$ <span style = "color:blue"> Criteria for spontaneous processes </span> $\rightarrow$ 2nd law thermodynamics $\rightarrow$ 2nd law thermodynamics </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> 2nd law thermodynamics </primary>
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- Quantify randomness $\rightarrow$
- we introduce a thermodynamic parameter 
- Entropy (S)
- for any  spontaneous process the value of entropy of system + entropy of surroundings will increase
- $\Delta S_{\text {system }}+\Delta S_{\text {surrounding }}>0$
- isolated System
- $\Delta S_{\text {system }}>o$

- 2nd law thermodynamics
 
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<footer style = "font-size: 18px">Criteria for spontaneous processes $\rightarrow$ Criteria for spontaneous processes $\rightarrow$ <span style = "color:blue"> 2nd law thermodynamics </span> $\rightarrow$ 2nd law thermodynamics $\rightarrow$ 2nd law thermodynamics </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> 2nd law thermodynamics </primary>
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- $S$ -  extensive state function
- $\Delta S$ - independent of path
- we will try to get the value of S
- If we add some energy as heat, entropy increases
- q - only appears during a process 
- $q$ should be related to $\Delta s$
- $q>0, \Delta s>0$

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<footer style = "font-size: 18px">Criteria for spontaneous processes $\rightarrow$ 2nd law thermodynamics $\rightarrow$ <span style = "color:blue"> 2nd law thermodynamics </span> $\rightarrow$ 2nd law thermodynamics $\rightarrow$ Entropy </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> 2nd law thermodynamics </primary>
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- $T_1>T_2$
 - $q_{sys } < 0 \Delta S_{system} < 0$
 - $q_{surr }>0 \Delta S_{surr} > 0$
 - $q_{sys}+q_{surr}=0$
 - if $\Delta S$ is only related to q
 - $\Delta S = O$

- $\Delta S_total > 0 $
 - $|\Delta S_{system}|<\Delta S_{surr}|$
 - $\Delta S \propto \frac{1}{T}$
 - $T_1>T_2$

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<footer style = "font-size: 18px">2nd law thermodynamics $\rightarrow$ 2nd law thermodynamics $\rightarrow$ <span style = "color:blue"> 2nd law thermodynamics </span> $\rightarrow$ Entropy $\rightarrow$ Entropy </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-7 </Success>
### <primary style="font-size:24px"> Entropy </primary>
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- $\Delta S=\frac{q_{\text {rev }}}{T}$
- $\frac{q_{\text {rev }}}{T}$: energy transfer to system reversibly 
- T: temperature in K

- Entorpy?
 -  liq $\rightarrow$ gas  $\Delta S_{sys}>0$
 - liq $\rightarrow$ solid  $\Delta S_{sys}<0$

- (water)
 - $125^{\circ} \mathrm{C} \quad$ water $\rightarrow$ vapour (endothermic)
 - $-25^{\circ} \mathrm{C}$ water $\rightarrow$ ice (exothermic)

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<footer style = "font-size: 18px">2nd law thermodynamics $\rightarrow$ 2nd law thermodynamics $\rightarrow$ <span style = "color:blue"> Entropy </span> $\rightarrow$ Entropy $\rightarrow$ Thank you </footer>