Abstract The reaction and mechanism of tartrazine and molybdate ion in hydrochloric acid has been investigated at a temperature of T = 30±1 oC, [H+] = 1 x 10-4 mol dm-3 and ionic strength, µ= 1.0 mol dm-3. The reaction is first order with respect to both tartrazine and molybdate ion. The rate of reaction was found to decrease with increase in ionic strength concentration and increased with increase in dielectric constant concentration; added cation and anion also increased the rate of reaction. The reaction rate showed increase as the [H+] increased which obeyed the rate law:
at 30±1oC, [H+] = 1×10-4, µ = 1.0 mol dm-3 (NaCl) and λmax = 560 nm.
Investigation of spectroscopic test did not indicate the formation of intermediate complex during the course of the reaction as suggested by absence of intercept in Michaelis- Menten plot and lack of shift in λmax. Hence a plausible mechanism in favour of outer-sphere mechanism has been proposed.