At constant temperature and pressure, if ΔH is positive and ΔS is negative, what

At constant temperature and pressure, if ΔH is positive and ΔS is negative, what can be said about ΔG?

At constant temperature and pressure, if ΔH is positive and ΔS is negative, what can be said about ΔG?

Step 1: Understand the symbols: ΔH represents enthalpy change, ΔS represents entropy change, and ΔG represents Gibbs free energy change.
Step 2: Recognize that ΔH is positive, which means the reaction absorbs heat (endothermic).
Step 3: Note that ΔS is negative, indicating that the disorder of the system decreases.
Step 4: Recall the Gibbs free energy equation: ΔG = ΔH - TΔS, where T is the temperature in Kelvin.
Step 5: Since ΔH is positive and ΔS is negative, the term -TΔS will also be negative (because a negative ΔS multiplied by a positive temperature is negative).
Step 6: Therefore, when you combine a positive ΔH and a negative -TΔS, the overall ΔG will be positive.
Step 7: Conclude that if ΔH is positive and ΔS is negative, then ΔG is positive, indicating that the reaction is non-spontaneous under these conditions.

Gibbs Free Energy – Gibbs Free Energy (ΔG) is a thermodynamic potential that measures the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure.
Enthalpy (ΔH) – Enthalpy (ΔH) is a measure of the total heat content of a system, and a positive ΔH indicates that the system absorbs heat.
Entropy (ΔS) – Entropy (ΔS) is a measure of the disorder or randomness in a system, and a negative ΔS indicates a decrease in disorder.
Gibbs Free Energy Equation – The relationship between ΔG, ΔH, and ΔS is given by the equation ΔG = ΔH - TΔS, where T is the temperature in Kelvin.