# Problem: Assume that the following reaction occurs at constant pressure: 2 Al(s) + 3 Cl2(g) → 2 AlCl3(s)(a) If you are given ΔH Delta {H}for the reaction, what additional information do you need to determine ΔE Delta {E} for the process?

###### FREE Expert Solution

Internal Energy:

$\overline{){\mathbf{∆}}{\mathbf{E}}{\mathbf{=}}{\mathbf{q}}{\mathbf{+}}{\mathbf{w}}}$

Recall that work (w) is given by:

$\overline{){\mathbf{w}}{\mathbf{=}}{\mathbf{-}}{\mathbf{P\Delta V}}}$

• (+): heat, q is gained by the system (i.e. endothermic rxn )

• (–): heat, q is released by the system (i.e. exothermic rxn)

• (+): work is done by the surroundings to the system (compression)

• (–): work is done by the system to the surroundings (expansion)

At constant P → q = ΔH (enthalpy)

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###### Problem Details

Assume that the following reaction occurs at constant pressure: 2 Al(s) + 3 Cl2(g) → 2 AlCl3(s)

(a) If you are given ΔH for the reaction, what additional information do you need to determine ΔE for the process?