Bromine reacts with hydrogen according to the overall reaction
Br₂(g) + H₂(g) → 2 HBr(g)
The concentration of Br₂ in a sealed vessel was monitored at 300 K, giving the data below.
Time (s) | 0 | 40 | 80 | 120
[Br₂] (mol L⁻¹) | 0.120 | 0.098 | 0.078 | 0.062
(a) Calculate the average rate of disappearance of Br₂ for the interval from 40 s to 120 s. Express your answer with units of mol L⁻¹ s⁻¹.
(b) Convert the rate obtained in part (a) to units of mol L⁻¹ min⁻¹.
(c) Determine the average rate of formation of HBr over the same 40 s to 120 s interval, including the correct sign convention. Explain how you used the stoichiometry of the balanced equation in your calculation.