Which statement about spontaneous reactions is true?

Which statement about spontaneous reactions is true?

• A. Spontaneous reactions require energy input to proceed
• B. Spontaneous reactions cannot occur without catalysts
• C. Spontaneous reactions always release energy as they proceed
• D. Spontaneous reactions have positive ΔG

Answer: (C)

Spontaneity is about Gibbs free energy. A process is spontaneous when ΔG is negative, meaning it can proceed without continuous input of energy from outside and the system releases free energy as it moves to a more stable state. That release of free energy is what allows the reaction to do work on the surroundings, even if heat flow isn’t the driving factor. Catalysts aren’t required for spontaneity; they only speed things up by lowering activation energy. A positive ΔG would mean the process is non-spontaneous under those conditions and would need external energy to proceed. So the statement that spontaneous reactions always release energy as they proceed aligns with the idea of negative ΔG and energy being released, rather than requiring energy input.

Spontaneity is about Gibbs free energy. A process is spontaneous when ΔG is negative, meaning it can proceed without continuous input of energy from outside and the system releases free energy as it moves to a more stable state. That release of free energy is what allows the reaction to do work on the surroundings, even if heat flow isn’t the driving factor. Catalysts aren’t required for spontaneity; they only speed things up by lowering activation energy. A positive ΔG would mean the process is non-spontaneous under those conditions and would need external energy to proceed. So the statement that spontaneous reactions always release energy as they proceed aligns with the idea of negative ΔG and energy being released, rather than requiring energy input.