Answer:
it will take 444.44 min to reach 0.25 M from 0.75 M
Explanation:
since the reaction constant is k= 6.00*10⁻³ L*mol⁻¹min⁻¹. For a reaction rate of the form
-dCa/dt=k*Caⁿ
doing a dimensional analysis
[dCa/dt]= mol/(L*min) = [k]*[Caⁿ] = L/(mol*min) * (mol/L)ⁿ
then only n=2 can comply with the dimensional analysis, therefore we get a the second order reaction . Thus
-dCa/dt=k*Ca²
-dCa/Ca² =k*dt
-∫dCa/Ca² =k*∫dt
(1/Ca₂ - 1/Ca₁)= k*Δt
Δt= 1/k*(1/Ca₂ - 1/Ca₁)
replacing values
Δt= 1/k*(1/Ca₂ - 1/Ca₁) = 1/(6.00*10⁻³ L*mol⁻¹min⁻¹)*(1/0.25 M - 1/0.75 M)= 444.44 min
