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Ch.18 - Free Energy and Thermodynamics
Chapter 18, Problem 27

Which of these processes is spontaneous? a. the combustion of natural gas b. the extraction of iron metal from iron ore c. a hot drink cooling to room temperature d. drawing heat energy from the ocean's surface to power a ship

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Spontaneity in Chemical Processes

A spontaneous process is one that occurs naturally without the need for external energy input. It is driven by the increase in entropy, or disorder, of the system and its surroundings. Spontaneity is often assessed using Gibbs free energy, where a negative change indicates a spontaneous reaction at constant temperature and pressure.
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Entropy

Entropy is a measure of the disorder or randomness in a system. In thermodynamics, processes that increase the total entropy of the universe are favored and tend to be spontaneous. For example, when a hot drink cools, the energy disperses into the surroundings, increasing entropy.
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Gibbs Free Energy

Gibbs free energy (G) is a thermodynamic potential that helps predict the spontaneity of a process at constant temperature and pressure. The change in Gibbs free energy (ΔG) is calculated as ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. A negative ΔG indicates a spontaneous process.
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