What is the Difference Between Spontaneous and Nonspontaneous Reactions?

The main difference between spontaneous and nonspontaneous reactions lies in whether they occur naturally without any external influence or require an external agent to proceed, respectively. Here are the key differences between the two types of reactions:

Spontaneous Reactions: These reactions take place without any external agent and tend to occur naturally under certain conditions. Examples include the melting of ice and the decay of radioactive isotopes. Spontaneous reactions can be slow or rapid, depending on the specific reaction and conditions.
Nonspontaneous Reactions: These reactions require an external agent, such as heat, light, or energy of some sort, to proceed. Examples include photosynthesis, where sunlight is required for plants to convert water and carbon dioxide into sugar, and the freezing of water into ice at normal temperatures and pressures. Nonspontaneous reactions can also be driven by connecting them to a spontaneous reaction through a common intermediate.

In summary, a reaction is considered spontaneous if it occurs naturally without any external influence, while a nonspontaneous reaction requires an external agent to take place.

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What is the Difference Between Spontaneous and Nonspontaneous Reactions?

Comparative Table: Spontaneous vs Nonspontaneous Reactions

Here is a table summarizing the differences between spontaneous and nonspontaneous reactions:

Feature	Spontaneous Reactions	Nonspontaneous Reactions
Definition	Reactions that favor the formation of products at the conditions under which the reaction is occurring.	Reactions that do not favor the formation of products at the conditions under which the reaction is occurring.
Gibbs Free Energy	Negative ΔG, indicating that the reaction releases energy.	Positive ΔG, indicating that the reaction absorbs energy.
Energy	Energy is released during the reaction, and it is not needed for the reaction to happen.	Heat is absorbed, and a constant form of energy is required for the reaction to occur.
Entropy	The reaction results in an increase in entropy.	The reaction results in a decrease in entropy.
Example	Combustion reactions, such as a roaring bonfire, where energy is released and the products have increased entropy.	An endothermic reaction like the formation of carbonic acid from carbon dioxide and water, which is not spontaneous at normal temperatures and pressures.

A spontaneous reaction occurs without the need for a continual input of energy from an external source, while a nonspontaneous reaction requires external energy to proceed. The spontaneity of a reaction is not correlated to the speed of the process; a spontaneous change may be rapid or extremely slow.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.