Write the reaction rate expressions for the following reactions in terms of the disappearance of the reactants and the appearance of products: (a) \(\mathrm{H}_{2}(g)+\mathrm{I}_{2}(g) \longrightarrow 2 \mathrm{HI}(g)\) (b) \(5 \mathrm{Br}^{-}(a q)+\mathrm{BrO}_{3}^{-}(a q)+6 \mathrm{H}^{+}(a q) \longrightarrow\) $$ 3 \mathrm{Br}_{2}(a q)+3 \mathrm{H}_{2} \mathrm{O}(l) $$

Short Answer

Expert verified
The rate of reaction (a) in terms of the disappearance of H2 and I2 or the appearance of HI is given as \( -\frac{1}{2}\frac{d[\mathrm{H}_{2}]}{dt} = -\frac{1}{2}\frac{d[\mathrm{I}_{2}]}{dt} = \frac{d[\mathrm{HI}]}{dt} \) and the rate of reaction (b) in terms of disappearance of the reactants Br-, BrO3- and H+ and formation of the products Br2 and H2O is given as \(-\frac{1}{5}\frac{d[\mathrm{Br}^-]}{dt} = -\frac{d[\mathrm{BrO}_{3}^-]}{dt} = -\frac{1}{6}\frac{d[\mathrm{H}^+]}{dt} = \frac{1}{3}\frac{d[\mathrm{Br}_2]}{dt} = \frac{1}{3}\frac{d[\mathrm{H}_2\mathrm{O}]}{dt}\)

Step by step solution

01

Write the rate expression for reaction (a)

In reaction (a) we have to divide the change in concentration of a reactant or product by the stoichiometric coefficient. In this case, the rate of reaction can be written in terms of the disappearance of H2 and I2 or the appearance of HI. If the reaction is proceeding in the direction as written, the rate can be expressed as follows: \( -\frac{1}{2}\frac{d[\mathrm{H}_{2}]}{dt} = -\frac{1}{2}\frac{d[\mathrm{I}_{2}]}{dt} = \frac{d[\mathrm{HI}]}{dt} \)
02

Write the rate expression for reaction (b)

Similarly, for reaction (b), we divide the change in concentration of each reactant or product by its stoichiometric coefficient. The rate can be expressed in terms of disappearance of the reactants Br-, BrO3- and H+ or the appearance of the products Br2 and H2O. If the reaction is proceeding in the direction as written, the rate can be expressed as follows: \(-\frac{1}{5}\frac{d[\mathrm{Br}^-]}{dt} = -\frac{d[\mathrm{BrO}_{3}^-]}{dt} = -\frac{1}{6}\frac{d[\mathrm{H}^+]}{dt} = \frac{1}{3}\frac{d[\mathrm{Br}_2]}{dt} = \frac{1}{3}\frac{d[\mathrm{H}_2\mathrm{O}]}{dt}\)

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Most popular questions from this chapter

The reaction \(\mathrm{H}+\mathrm{H}_{2} \longrightarrow \mathrm{H}_{2}+\mathrm{H}\) has been studied for many years. Sketch a potential energy versus reaction progress diagram for this reaction.

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