Below are some thermochemical data for the dissolution equilibrium of solid aluminum hydroxide in water: Al(OH)3(s) → Al3+(aq) + 3OH−(aq) ΔfH∘/kJ⋅mol−1 −1284 −538.4 −230.02 S∘/J⋅mol−1⋅K−1 85.4 −325 −10.9 Part A...

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Chemistry

Below are some thermochemical data for the dissolutionequilibrium of solid aluminum hydroxide in water:

Al(OH)3(s)→Al3+(aq)+3OH−(aq)
ΔfH∘/kJ⋅mol−1−1284−538.4−230.02
S∘/J⋅mol−1⋅K−185.4−325−10.9

Part A Compute ΔrH∘ (Express youranswer in kilojoules per mole as an integer.)

Part B Compute ΔrS∘ (Express youranswer in joules per mole per kelvin to one decimal place.)

Part C Compute ΔrG∘ at 298 K(Express your answer in kilojoules per mole as an integer.)

Part E Determine the equilibrium constant forthe dissolution of Al(OH)3 at 298 K

Part F Determine the Gibbs energy change forthe dissolution of Al(OH)3 when the concentrations ofAl3+ and OH− are both1.20×10−7mol⋅L−1 (Express your answer inkilojoules per mole as an integer.)

Part H At what temperature willAl(OH)3(s) be at equilibrium with Al3+ andOH−, each at 1.20×10−7mol⋅L−1?

Part I Explain why the entropy of dissolutionfor this reaction, solid Al(OH)3(s) dissolving to formAl3+ and 3OH−, is so negative. Match thewords in the left column to the appropriate blanks in the sentenceson the right.

lose, holds on to, low, is releasedfrom, gain, high

The Al 3+ ion has a quite __ charge so that it __water molecules, which causes the water molecules to __translational and rotational degrees of freedom so that the entropyassociated with Al 3+ in the aqueous phase is verynegative.

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3.9 Ratings (677 Votes)
Here basic concept of thermodynamics is applied Enthaply andentropy are calculated by difference of enthalpies    See Answer
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