Young Duk Lee

thanks alot for your reply.

i couldnt find the index numbering starts at 0 or 1. so in my case I am giving the reaction rate for ammonia decomposition and ammonia is the fifth material in my list of mixture-materials. 

so do I give the index 4 (if index numbering starts from 0) or should I give the index 5 (if the numbering starts from 1).