A 19th-century chemist, Marcellin Berthelot, suggested that all chemical processes that proceed spontaneously are exothermic.
True or False?
I thought it was true, but then in my chemistry textbook, I could not find this person's name. Can someone verify whether it is true or false?
Here is some information about Barthelot.
http://en.wikipedia.org/wiki/Marcellin_Berthelot
While it is true that MANY spontaneous reactions are exothermic, there are some endothermic reactions that are spontaneous. It is delta G (delta G = delta H -TtdeltaS) that must be negative to be spontaneous.
The statement is false, You got a perfect explanation from DrBob. Here is a less formal explanation based on the equation for deltaG:
Chemical and physical changes happen because of two universal trends:
A. A trend toward lower energy. This favors exothermic reactions as far as spontaneity goes.
B. A trend toward greater disorder (a rise in entropy). Greater disorder means formation of more particles, more mixing, and more particle motion. Increased temperature favors more disorder and spontaneity.
How the two trends work together, is described by the equation,
deltaG=deltaH-TdeltaS
To verify whether the statement "all chemical processes that proceed spontaneously are exothermic" is true or false, we can use scientific sources and knowledge to investigate it.
First, let's address the claim made by Marcellin Berthelot. Marcellin Berthelot was indeed a chemist who lived in the 19th century and made significant contributions to the field of chemistry. However, it is important to note that not all of his ideas and conclusions have stood the test of time. Therefore, it is possible that this particular statement might not accurately reflect our current understanding.
To determine whether the statement is true or false, we need to consider the concept of spontaneity in chemistry. Spontaneous processes are those that occur without any external influence or intervention, driven solely by the inherent properties of the system. In chemistry, spontaneity is related to the thermodynamic concept of Gibbs free energy (∆G).
If a chemical reaction is thermodynamically spontaneous (∆G < 0), it means that the reaction can occur naturally without the need for external energy input. However, the sign of ∆G, whether positive or negative, does not directly indicate whether a reaction is exothermic or endothermic.
The enthalpy change (∆H) is the measure of heat energy released or absorbed during a chemical reaction. If ∆H is negative, the reaction is exothermic (heat is released), while a positive ∆H indicates that the reaction is endothermic (heat is absorbed).
So, in summary, the statement "all chemical processes that proceed spontaneously are exothermic" is false. Spontaneity and the direction of energy flow (exothermic or endothermic) are two separate concepts in chemistry. It is possible for a spontaneous reaction to be either exothermic or endothermic, depending on the relative magnitudes of enthalpy (∆H) and entropy (∆S) changes.
When verifying scientific information, it is always best to consult reliable sources such as textbooks, scientific literature, or reputable websites. While Marcellin Berthelot was an influential chemist, his contributions might not align with our current understanding if they have been debunked or disproven by subsequent research.