Estimate the enthalpy change at 400 K that accompanies the reaction: Li(s)+(1)/(2)Cl2(g)-Li

step 1 So we know the bomb entropy of lithium 2 is 110 kilo per mole. And we also know for lithium, EA1

Estimate the enthalpy change at 400 K that accompanies the...

Estimate the enthalpy change at $400 \mathrm{K}$ that accompanies the reaction: \[ \mathrm{Li}(\mathrm{s})+\frac{1}{2} \mathrm{Cl}_{2}(\mathrm{g})-\mathrm{LiCl}(\mathrm{s}) \] if $\Delta_{\mathrm{f}} H^{\circ}(298 \mathrm{K}) \mathrm{LiCl}(\mathrm{s})=-408.6 \mathrm{kJ} \mathrm{mol}^{-1},$ and values of $C_{P}(298 \mathrm{K})$ are $\mathrm{Li} 24.8, \mathrm{Cl}_{2} 33.9$ and $\mathrm{LiCl}$ \[ 48.0 \mathrm{JK}^{-1} \mathrm{mol}^{-1}. \]

Estimate the enthalpy change at $400 \mathrm{K}$ that accompanies the reaction:
\[
\mathrm{Li}(\mathrm{s})+\frac{1}{2} \mathrm{Cl}_{2}(\mathrm{g})-\mathrm{LiCl}(\mathrm{s})
\]
if $\Delta_{\mathrm{f}} H^{\circ}(298 \mathrm{K}) \mathrm{LiCl}(\mathrm{s})=-408.6 \mathrm{kJ} \mathrm{mol}^{-1},$ and
values of $C_{P}(298 \mathrm{K})$ are $\mathrm{Li} 24.8, \mathrm{Cl}_{2} 33.9$ and $\mathrm{LiCl}$
\[
48.0 \mathrm{JK}^{-1} \mathrm{mol}^{-1}.
\]

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Key Concepts

Reaction Enthalpy

Reaction enthalpy is the overall heat change associated with a chemical reaction occurring at constant pressure. It is calculated from the standard enthalpies of formation of the reactants and products and can be adjusted for non-standard temperatures via heat capacity integration.

Heat Capacity Integration

Heat capacity integration involves using heat capacities (Cp values) to determine how much energy is needed to change the temperature of a substance. In thermochemical calculations, this integration is used to correct enthalpy values from one temperature to another, accounting for temperature-dependent energy changes.

Standard Enthalpy of Formation

The standard enthalpy of formation is the heat change that occurs when one mole of a compound is formed from its elements in their most stable forms at 298 K and 1 atm. It serves as a reference for calculating the energies of reactions using tabulated data.

Kirchhoff's Law

Kirchhoff's Law allows the adjustment of a reaction’s enthalpy change with temperature. It states that the change in reaction enthalpy with temperature can be determined by integrating the difference in heat capacities of the products and reactants over the temperature range.

Transcript

00:03 So we know the bomb entropy of lithium 2 is 110 kilo per mole.

00:36 And we also know for lithium, ea1 of lithium is 60 kilojou per mole.

00:53 We need to find the enthalpy change of a reaction of a reaction.

00:58 Reaction related to lithium, that is this one.

01:07 Lithium 2 produce lithium anion.

01:29 So what is the entropy change for this one? okay, so we're gonna look at bond entropy of lithium 2 again.

01:41 What does it mean? it means a lithium, that's a lithium bond, lithium lithium bond.

01:55 And in the gas state, and then the bond is broken and produce lithium atom in gasiest state.

02:15 And then that is how much energy is involved.

02:23 That's 110 can jewel per more.

02:29 And that is what the and selfie means, we can write an equation.

02:35 And what about affinity, first affinity of lithium? we can also write an equation.

02:45 So it's in the get lithium atom in the gaseous state, binds with an electron, and produce lithium an ion, lithium negative in the gases stay and that is the energy is it should be negative because binding with an electron will release energy so that's kilo kilo per mole and then how how do these two equations related to the one that we need to solve for so we can apply heslor here to manipulate these two equations so that when we add the two equations together, we get the one we want...

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