Question

which statements correctly describe a spontaneous reaction? select all that apply. the reaction always occurs rapidly. activation energy is required for the reaction to go to completion. the reaction must be catalyzed by an enzyme to go to completion. the products always have lower free energy than the reactants.

Explanation:

• Spontaneous reactions do not always occur rapidly. Rate of reaction is different from spontaneity.
• Activation energy is required for most reactions (including spontaneous ones) to overcome the energy barrier and go to completion.
• Enzymes are biological catalysts. A spontaneous reaction does not necessarily need to be catalyzed by an enzyme (though it can be). There are non - enzymatic spontaneous reactions.
• For a spontaneous reaction, the change in Gibbs free energy ($\Delta G=\Delta H - T\Delta S<0$). This implies that the products have lower free energy than the reactants.

Answer:

Activation energy is required for the reaction to go to completion. The products always have lower free energy than the reactants.