Related Experiment Video
Updated: Mar 12, 2026

Quantitative Hardness Measurement by Instrumented AFM-indentation
Published on: November 22, 2016
Statistical Significance of the Maximum Hardness Principle Applied to Some Selected Chemical Reactions
Ranajit Saha1, Sudip Pan2, Pratim K Chattaraj3
1Department of Chemistry and Centre for Theoretical Studies, Indian Institute of Technology Kharagpur, Kharagpur 721302, India. ranajitsahachem@gmail.com.
Abstract:
The validity of the maximum hardness principle (MHP) is tested in the cases of 50 chemical reactions, most of which are organic in nature and exhibit anomeric effect. To explore the effect of the level of theory on the validity of MHP in an exothermic reaction, B3LYP/6-311++G(2df,3pd) and LC-BLYP/6-311++G(2df,3pd) (def2-QZVP for iodine and mercury) levels are employed. Different approximations like the geometric mean of hardness and combined hardness are considered in case there are multiple reactants and/or products. It is observed that, based on the geometric mean of hardness, while 82% of the studied reactions obey the MHP at the B3LYP level, 84% of the reactions follow this rule at the LC-BLYP level. Most of the reactions possess the hardest species on the product side. A 50% null hypothesis is rejected at a 1% level of significance.
More Related Videos
Related Concept Videos
Chemical Reactions
The relative amounts of reactants and products represented in a balanced chemical equation are often referred to as stoichiometric amounts. However, in...
Chemical Reactions
Chemical Reactions Rearrange Atoms into New Substances
A chemical reaction takes starting materials—the reactants—and changes them...
Le Chatelier's Principle: Changing Concentration
Temperature Dependence on Reaction Rate
Atoms, molecules, or ions must collide before they can react with each other. Atoms must be close together to form chemical bonds. This premise is the basis for a theory that explains many observations regarding chemical kinetics, including factors affecting reaction rates.
The collision theory is based on the postulates that (i) the reaction rate is proportional to the rate of reactant collisions, (ii) the reacting species collide in an orientation allowing contact between...
Hess's Law
Predicting Reaction Outcomes

