Answer:
250 mmol are left after 26.60 secs ≅ 26.6 seconds
Explanation:
zero order kinetics formula is:
[A] = [A₀] - kt
where [A] = amount left; [A₀] = amount remaining; k = rate constant; t = time
concentration [A₀] = mole/volume = 0.5 mole/2.0L = 0.25
[A] = 0.25 mole/2.0L = 0.125 M
k = 0.0047 Ms⁻¹
t = {[A]-[A₀]}/-k = (0.125 - 0.25)/(-0.0047) = 26.60 seconds = 26.6 seconds
the amount is reduced by half after 26.6 seconds