Consider the reaction 2 hbr (g) à h2 (g) + br2 (g)

a. express the rate of the reaction in terms of the change in concentration of each of the reactants and products.

b. in the first 25.0 s of this reaction, the concentration of hbr drops from 0.600 m to 0.512 m. calculate the average rate of the reaction during this time interval.

The decomposition of HBr takes place according to the reaction below,

2HBr (g) = H2 (g) + Br2 (g)

a) Rate of reaction is the measure of the change in concentration of the reactants or the change in concentration of the product per unit time (seconds).

Therefore;

Rate = - 1/2 (Δ (HBr) / Δt = Δ (H₂) / Δt = Δ (Br₂) / Δt,

where ΔHBr is the change in concentration of HBr (reactant), ΔH₂ is the change in hydrogen concentration, ΔBr₂ is the change in bromine concentration and Δt is the change in time.

b) Average rate of reaction after 25 sec will be,

rate = - 1/2Δ (HBr) / Δt

= - 1/2 (0.512 M - 0.6 M) / (25 s-0 s)

= - 1/2 (-0.088) / 25

= 0.00176 M/s