W. Ott
1972
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Abstract
The kinetics and mechanism of the reaction between lead orthosilicate and potassium carbonate were studied using isothermal weight change determinations and TG. These experiments were performed in air over the temperature range 550°–650°C. The solid state reaction: $${K_2}C{O_3} + 2\left( {2PbO \cdot Si{O_2}} \right) \to {K_2}O \cdot 2PbO \cdot 2Si{O_2} + 2PbO + C{O_2}$$ was nuclei growth controlled and described by the equation: $$\ln \frac{1}{{1 - x}} = K{t^{2/3}}$$ where x is the fraction of the reaction completed at time t. K is the rate constant. The exponent value of 2/3 infers a nuclei growth model with a decreasing nucleation rate which exhibits one dimensional diffusion controlled growth. The variation of the rate constant, with the inverse square of the lead orthosilicate particle size, is consistent with the proposed model. The procedural activation energy for this reaction was calculated to be 40.2 k-cal/mole.