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What is the effect of increasing temperature on the spontaneity of an endothermic reaction with a positive ΔS?
Increasing temperature makes the reaction more likely to be spontaneous (more negative ΔG).
What is the effect of a large positive ΔH on the solubility of a substance?
A large positive ΔH makes the substance less likely to dissolve spontaneously, especially at lower temperatures.
What is the effect of a large positive ΔS on the solubility of a substance?
A large positive ΔS makes the substance more likely to dissolve spontaneously, especially at higher temperatures.
What happens to entropy during a phase change from solid to gas?
Entropy increases because the molecules have more freedom to move around, leading to greater disorder.
What happens if ΔG = 0?
The reaction is at equilibrium.
What are the differences between enthalpy and entropy?
Enthalpy (ΔH): Measures heat transfer in a reaction (exothermic or endothermic). Entropy (ΔS): Measures the disorder or randomness of a system.
Compare spontaneous and non-spontaneous reactions in terms of Gibbs Free Energy and the equilibrium constant (K).
Spontaneous: ΔG < 0, K > 1 (favors products). Non-spontaneous: ΔG > 0, K < 1 (favors reactants).
What is the formula for calculating Gibbs Free Energy?
ΔG = ΔH - TΔS, where ΔG is Gibbs Free Energy change, ΔH is Enthalpy change, T is Temperature (in Kelvin), and ΔS is Entropy change.
Describe the process of dissolving a substance in terms of enthalpy and entropy.
Energy is needed to break solute-solute and solvent-solvent attractions (endothermic, +ΔH). Forming new solute-solvent attractions releases energy (exothermic, -ΔH). Entropy usually increases as the solute becomes more dispersed in the solution (+ΔS).
How do you determine if the dissolution of a substance is spontaneous?
Calculate ΔG using the formula ΔG = ΔH - TΔS. If ΔG < 0, the dissolution is spontaneous. If ΔG > 0, the dissolution is non-spontaneous.