What is rate constant of a first order reaction having half life 138.6 minute?

For the reaction,

$$ 3 \mathrm{I}_{(\mathrm{aq})}^{-}+\mathrm{S}_2 \mathrm{O}_{8(\mathrm{aq})}^{2-} \longrightarrow 2 \mathrm{SO}_{4(\mathrm{aq})}^{2-}+\mathrm{I}_{3(\mathrm{aq})}^{-} $$

rate of formation of $\mathrm{SO}_{4(\text { aq })}^{2-}$ is $0.044 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{~s}^{-1}$.

What is the rate of consumption of $\mathrm{S}_2 \mathrm{O}_{8(\mathrm{aq})}^{2-}$ ?

Calculate activation energy for a reaction if it's rate doubles when temperature is raised from $20^{\circ} \mathrm{C}$ to $35^{\circ} \mathrm{C}\left(\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)$