chemistry-class-11-unit-06-chapter-04-chemical-thermodynamics-l-4-8-f34wzbm9g9q

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Recap </primary>
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- Essential concepts and definitionsw of thermodynamics
- Heat, work \& energy, internal energy
- First Law of thermodynamics
- Calculation of work, heat in ditferent process for an ideal gas
- Enthalpy and heat capacity
- Determination of $\Delta \mathrm{U}$ and $\Delta \mathrm{H}$
- Change in enthalpy in different processes / reactions
- Enthalpy of reaction
- Enthalpy of formation
- Enthalpy of phase transition

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<footer style = "font-size: 18px"> $\rightarrow$ Chemical thermodynamics $\rightarrow$ <span style = "color:blue"> Recap </span> $\rightarrow$ Enthalpy (H) $\rightarrow$ Enthalpy (H) </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Enthalpy (H) </primary>
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- $ H=U+P V$
- $ \Delta U \approx \Delta H \quad \text { solid, liquid }$
- $ \Delta H=\Delta U+\Delta n_g R T \quad \text { (ideal gasess) }$
- Any process at constant $v \quad \Delta u=q_v$ 
- Any process at constant $p \quad \Delta H=q_p$
- For any Process, for ideal gas, closed system
- $ \Delta U=C_V \Delta T$
- $ \Delta H=C_P \Delta T$
- $C_p>C_v$ for gives
- $c_p$ $\approx$ $c_y$ for solid and liq
- ideal gas; $cp-cv=n R$

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<footer style = "font-size: 18px">Chemical thermodynamics $\rightarrow$ Recap $\rightarrow$ <span style = "color:blue"> Enthalpy (H) </span> $\rightarrow$ Enthalpy (H) $\rightarrow$ Enthalpy (H) </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Enthalpy (H) </primary>
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- q, w, $\Delta u$, $\Delta H$
- $\text { (i) Reversible adiabatic expansion of an ideal gas }$ 
- $q=0 \quad w<0 \quad \Delta u=q+w$
- $\Delta u <0$
- $\Delta u=C_v \Delta T$ or
- $\Delta u < 0, \Delta T < 0$
- $\Delta H = \Delta V + \Delta (PV)$
- $\Delta H=\Delta V + nR \Delta T$
- $\Delta H<0$
- $\Delta H = C_p \Delta T$
- $\Delta H <0$

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<footer style = "font-size: 18px">Recap $\rightarrow$ Enthalpy (H) $\rightarrow$ <span style = "color:blue"> Enthalpy (H) </span> $\rightarrow$ Enthalpy (H) $\rightarrow$ Enthalpy (H) </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> First law of thermodynamics </primary>
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- **Bomb calorimeter**
- $\Delta U = Cv \Delta T \rightarrow constant \quad volume$
- $\Delta H$
- constant pressure process- 1 atm
- Heat of reaction also known as  enthalpy of reaction
- $\Delta rH / \Delta Hr$
- exothermic  $q_p<0;  \Delta_r H < 0$
- endothermic   $a_p>0;  \Delta_r H > 0$
- $\Delta H = C_p \Delta T $

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

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> First law of thermodynamics </primary>
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- 1g of graphite is burnt in a bomb calorimeter in exchange of oxygen at 298 K and 1 atm process
- $C \text { (graphite })+\mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g)$
- q<0
- $T_1=298 \mathrm{K}$
- $T_2=299 \mathrm{K}$
- $\Delta T=1 K$
- $C_p=20.7 KJ k^-1$
- $\Delta_r H=?$
- $q=C_p \Delta T$
- $\frac{-20.7 KJ mol^{-1} \times 12 g mol^{-1}}{1g}$
- $ -2.48 \times 10^2 kJ \quad mol^{-1}$

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

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Problem </primary>
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- Classify each of the following properties as intensive or extensive and give the SI units of each
    - density - Intensive $kg m^-3$
    - $U:$ extensive $J$
    - $H_n$ - intensive $J  mol^-1$
    - $C_r$ - extensive $J k^-1$
    - $c- intensive\quad JK^-1  Kg^-1$
    - Cin - intensive $J K^{-1}$ mol $^{-1}$
    - $P$ - intensive $Pa$
    - molar mass - intensive $kg mol^-1$
    - $T$ - intensive $K$

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

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Reaction enthalpy </primary>
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- Enthalpy change of a reaction 
 - $\Delta r H or \Delta H_r$
- A chemical reaction
 - $Reactants \rightarrow Products$
 - $\Delta H \equiv \Delta r H$
 - $\Delta rH$ = (sum of enthalpy of products) - (sum of enthalpy of reactants)
 - $\sum a_i H products -\sum b_i H reactants$
- $a_i and \quad b_i$ are the stoichiometric coefficient of the products and reactants respectively  in the  balanced chemical equation

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<footer style = "font-size: 18px"> $\rightarrow$ Problem $\rightarrow$ <span style = "color:blue"> Reaction enthalpy </span> $\rightarrow$ Reaction enthalpy $\rightarrow$ Reaction enthalpy </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Reaction enthalpy </primary>
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- $\mathrm{CH}_4(g)+2 \mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g)+2 \mathrm{U}_2 \mathrm{O}(e)$
- $\Delta_{r H}=\sum a_i H_{\text {product }}-\sum b_i H_{\text {reactants }}$
- $\left[H_m\left(co_2, g\right)+2 H_m\left(H_2 o,l\right)\right]$ $-\left[\mathrm{H_m CH}\right.$ (g) $\left.+2 \mathrm{H}_2\left(\mathrm{O}_2, g\right)\right]$
- $H_m$ = molar enthalpy
- exothermic $\Delta r H <0$
- endothermic $\Delta rH >0$

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<footer style = "font-size: 18px">Problem $\rightarrow$ Reaction enthalpy $\rightarrow$ <span style = "color:blue"> Reaction enthalpy </span> $\rightarrow$ Reaction enthalpy $\rightarrow$ Reaction enthalpy </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Reaction enthalpy </primary>
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- $\Delta r H$ depends on the conditions under which a reaction is carried out
- we must need to specify standard conditions
- Reactants (in standard conditions) $\rightarrow$ Products (in standard conditions)
 - $\Delta H \equiv \Delta rH^ {o}$
- standard heat of reaction.
- Standard Conditions?
- $ H_m$ = Molar enthalpy
- $H_m^ {o}$ = Standard molar enthalpy

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<footer style = "font-size: 18px">Reaction enthalpy $\rightarrow$ Reaction enthalpy $\rightarrow$ <span style = "color:blue"> Reaction enthalpy </span> $\rightarrow$ Reaction enthalpy $\rightarrow$ Pure gas </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Pure gas </primary>
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- For the reaction -
- a A+b B $\rightarrow$ c C+d D
- Standard reaction enthalpy at T
 - $\Delta H^oT$ = $C  H_m^o,{_T} (C)$ $+ d  H_m^o,{_T} (D)$ $-a H_m^o,{_T} (A)$ $- b  H_m^o,{_T} (B)$
- $ H_m^o,{_T} (A)$ = Standard moler enthalpy of A at temperature=T
- a,b,c,d = Stoichiometric coefficients in balanced chemical equation is unitless
- $\Delta rH^o_{T}$ will have same dimention
- $\Delta  H_m^o,{_T}$  $Jmol^{-1}$ , $cal mol^{-1}$

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<footer style = "font-size: 18px">Reaction enthalpy $\rightarrow$ Pure gas $\rightarrow$ <span style = "color:blue"> Pure gas </span> $\rightarrow$ Pure gas $\rightarrow$ Pure gas </footer>

### <Success style="font-size:25px"> Chemical Thermodynamics L-4 </Success>
### <primary style="font-size:24px"> Pure gas </primary>
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- Standard molar enthalpy
- $rH^\circ_T$  $\Rightarrow$ $H_m^o,{_T}$ $\Rightarrow$ $H^\circ m $
- Standard heat of formation
- $\Delta_f H_T^{\circ}$ of a pure substance at a specific temperature T is $\Delta r H^{\circ}$ for the process / reaction in which one mole of substance in its standard state at T is formed from the corresponding separated elements at T, each  being in its reference state/form/phase

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<footer style = "font-size: 18px">Pure gas $\rightarrow$ Pure gas $\rightarrow$ <span style = "color:blue"> Pure gas </span> $\rightarrow$ Pure gas $\rightarrow$ Thank you </footer>