In 1927, Prof. W. Jander experimented the reaction rate of solid particle and derived the following theoretical equation;
(1-3√1-w)²=kt,
where w was the fractions of reacted part in sold particle, t the time and k the constant.
The author pointed out that Jander's equation, based on the assumption of the equal particlesize, would not hold good of actual particle that had a irregularity of particle-radus.
Considering on the statistical distribution of particle-size, the author derived a new theoretical equation and criticized Jander's resalts of experiment on this point of view.
The equation is
1-w=∫(r-q)³f(r)dr/∫r³f(r)dr,
where r is the radius of particle, f(r) the distribution function of the radius and q the thickness of reacted layer in the solid particle.