When 0.52 g of H₂ and 0.19 g of I₂ are confined to a reaction vessel of volume 750. mL and heated to 700. K, they react by a second-order process (first order in each reactant), with kr 5 0.063 L · mol^–1 · s^–1 in the rate law (for the rate of formation of HI).

(a) What is the initial reaction rate?

(b) By what factor does the reaction rate increase if the concentration of H₂ present in the mixture is doubled?