Question

Just as the depletion of stratospheric ozone today threatens life on Earth today, its accumulation was one of the crucial processes that allowed life to develop in prehistoric times. You must have the correct sig figs.

3 O2 (g) ---> 2 O3 (g)
(a) Express the rate of reaction in terms of the rate of disappearance of O2 and the rate of appearance of O3.
Rate = _______ (delta)[O2]/(delta)t and Rate =______(delta)[O3]/(delta)t
(b) At a given instant, the rate of disappearance of O2 is 1.61 10-5 mol/Ls. What is the rate of appearance of O3?
______ mol/Ls

Answer 1

Answer:

(a) rate = -(1/3) Δ[O₂]/Δt = +(1/2) Δ[O₃]/Δt  

(b) Δ[O₃]/Δt = 1.07x10⁻⁵ mol/Ls

Explanation:

By definition, the reaction rate for a chemical reaction can be expressed by the decrease in the concentration of reactants or the increase in the concentration of products:    

aX → bY (1)

$rate= -\frac{1}{a} \frac{\Delta[X]}{ \Delta t} = +\frac{1}{b} \frac{\Delta[Y]}{ \Delta t}$

where, a and b are the coefficients of de reactant X and product Y, respectively.        

(a) Based on the definition above, we can express the rate of reaction (2) as follows:      

3O₂(g) → 2O₃(g) (2)    

$rate = -\frac{1}{3} \frac{\Delta[O_{2}]}{\Delta t} = +\frac{1}{2} \frac{ \Delta[O_{3}]}{ \Delta t}$ (3)

(b) From the rate of disappearance of O₂ in equation (3), we can find the rate of appearance of O₃:  

$rate = +\frac{1}{2} \frac{\Delta[O_{3}]}{ \Delta t} = -\frac{1}{3} \frac{\Delta[O_{2}]}{ \Delta t}$

$+\frac{\Delta[O_{3}]}{ \Delta t} = -\frac{2}{3} \frac{\Delta[-1.61 \cdot 10^{-5}]}{ \Delta t}$          

$\frac{\Delta[O_{3}]}{ \Delta t} = 1.07 \cdot 10^{-5} \frac{mol}{Ls}$

So the rate of appearance of O₃ is 1.07x10⁻⁵ mol/Ls.

           

Have a nice day!