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Imagine a 1kg block of ice that has completely melted at room temperature. If melting is a spontaneous reaction, then wouldn't that mean the products (1kg of water) would have less Gibbs free energy than the reactants (1kg of ice)? I am confused because water is more disordered than ice and less stable, so it should have more free energy than ice.

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Final answer:

In the melting of ice, the entropy of the system increases due to the transition from an ordered solid state to a disordered liquid state. The Gibbs free energy decreases, making the process spontaneous as per the second law of thermodynamics.

Step-by-step explanation:

The question is focused on the concept of Gibbs free energy changes during phase transitions, specifically the melting of ice into water.

The entropy change associated with this process, as well as the concept of spontaneity of the reaction, are considered. In the melting of ice at room temperature, the reaction H2O(s) +6.01 kJ → H2O(l) reflects the fact that liquid water is more disordered than solid ice, and thus has higher entropy.

The melting of 1kg of ice into 1kg of water at room temperature is a spontaneous process because the Gibbs free energy of the system decreases. The increase in disorder compensates for any decrease in stability, according to the second law of thermodynamics which states that the entropy of the universe increases for spontaneous processes.

Disorder in a system refers to the randomness and movement of its molecules. When ice melts to form water, the systematic arrangement of water molecules in a crystal structure (ice) is replaced by a more random and less orderly movement of these molecules in the liquid state.

As a result, the entropy of the system increases, because the disorder within the system increases, conforming to the second law of thermodynamics which states that the total entropy of the universe increases in a spontaneous process.

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