Problem: Given:P4(s) + 5O2(g)⟶P4O10(s)                  ΔG° 298 = −2697.0 kJ/mol2H2(g) + O2(g)⟶2H2O(g)                  ΔG° 298 = −457.18 kJ/mol6H2O(g) + P4O10(s)⟶4H3 PO4(l)      ΔG°298 = −428.66 kJ/mol(a) Determine the standard free energy of formation, ΔG f ° , for phosphoric acid.

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FREE Expert Solution

We can use Hess’s Law to determine the Δf for the formation of phosphoric acid (H3PO4):


1. 6 H2O(g) + P4O10(s) ⟶ 4 H3 PO4(l)      ΔG°298 = −428.66 kJ/mol

2. 2 H2(g) + O2(g) ⟶ 2 H2O(g)                  ΔG° 298 = −457.18 kJ/mol

3. P4(s) + 5 O2(g) ⟶ P4O10(s)                    ΔG° 298 = −2697.0 kJ/mol


Adding the current sequence:

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Problem Details

Given:

P4(s) + 5O2(g)⟶P4O10(s)                  ΔG° 298 = −2697.0 kJ/mol

2H2(g) + O2(g)⟶2H2O(g)                  ΔG° 298 = −457.18 kJ/mol

6H2O(g) + P4O10(s)⟶4H3 PO4(l)      ΔG°298 = −428.66 kJ/mol

(a) Determine the standard free energy of formation, ΔG f ° , for phosphoric acid.