The question asks to state a suitable technique to obtain rate data for the following reaction:
H2 (g) + I2 (g) -> 2HI (g)
At a first glance I know that this reaction is supposed to be reversible as we used to use it when demonstrating no change in equilibrium position on changing pressure as the two sides have the same number of moles etc.
Anyway, the equation given indicates the reaction goes to completion so that is what we will work with.
The answer is:
Withdraw samples at regular time intervals. Stop the reaction in the sample by adding sodium hydrogencarbonate. Add excess potassium iodide and titrate the liberated iodine with standard sodium thiosulfate(VI) solution
According to what I know, sodium hydrogen carbonate reacts with acids (which in this case is HI).
Can someone explain which species will react with sodium hydrogen carbonate?
Additionally, I would be grateful if you included a refresher on the reason we add iodate(V) ions before titrating with thiosulfate.
Thanks in advance!