Kinetics of the Nickel-Chlorine Reaction at Temperatures Between 350 and 600 C

The kinetics of the nickel-chlorine reaction between 350 and 600 C (622 and 1112 F) were studied using a quartz vacuum microbalance. The results fall into three distinct patterns. Up to 433 C (810 F), a parabolic rate law is observed. Between 433 C and 525 C (975 F), the reaction proceeds at a parabolic rate until a steady state thickness of chloride layer is formed after which there is a linear decrease in weight with time. Above 525 C, only linear decrease in weight is observed. Applying the Tedman equation for simultaneous parabolic formation and evaporation to the chloride layer, parabolic rate constants were calculated in the 433-525 C region. The plot of the logarithms of these rate constants versus 1/T followed the same straight line as that similarly formed from the parabolic constants determined directly in the lowest temperature region. It is suggested that the nickel-chlorine reaction in the 350-525 C is diffusion controlled up until a steady state thickness is formed.