ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 19, Number 5
JKCSEZ 19(5)
October 20, 1975 

The rates of consumption of iodine and gas evolution in hydrazine-iodine reaction in the presence of large excess of hydrazine have been studied in the pH range 0.5∼7. They are the same at very low pH and both increase to respective asymptotic values as pH is increased. The rate of iodine consumption is three orders of magnitude faster than the rate of gas evolution at higher pH. The results are explained by postulating that N2H4 but not protonated form reacts with iodine and an intermediate, probably N2H2I2, is formed which decomposed by first order reaction of rate constant about 1.5×10-3 sec-1 in neutral and weakly acidic solutions.