Q.For the reaction, $\mathrm{3I^-(aq) + S_2O_8^{2-}(aq) \longrightarrow I_3^-(aq) + 2\ SO_4^{2-}(aq)}$. Calculate the rate of formation of I$_3^-$, the rates of consumption of I$^-$ and S$_2$O$_8^{2-}$ and the overall rate of reaction if the rate of formation of SO$_4^{2-}$ is 0.022 moles dm$^{-3}$ sec$^{-1}$

The rate of a reaction is how rapidly its reactants are consumed or its products appear. It is expressed as either an AVERAGE rate over a finite time interval, $\text{rate}=\Delta c/\Delta t$, or the true INSTANTANEOUS rate at one exact moment, $\text{rate}=dc/dt$, found as the slope of a tangent drawn to a concentration-versus-time curve. For a simple 1:1 reaction $A\rightarrow B$, the rate of consumption of A equals the rate of formation of B: $\text{rate}=-d[A]/dt=+d[B]/dt$. When stoichiometric coefficients differ, as in $aA+bB\rightarrow cC+dD$, each species' own rate of change must first be …