Answer : The concentration of AB after 14.0 s is, 0.29 M
Explanation :
The expression used for second order kinetics is:
![kt=(1)/([A_t])-(1)/([A_o])](https://img.qammunity.org/2021/formulas/physics/college/tlg6nth7imx9pwjb4oksbydlkeyozanniz.png)
where,
k = rate constant =

t = time = 14.0 s
= final concentration = ?
= initial concentration = 1.50 M
Now put all the given values in the above expression, we get:
![0.20* 14.0=(1)/([A_t])-(1)/(1.50)](https://img.qammunity.org/2021/formulas/chemistry/college/gbrd17q81vdp91c0yam1itdnu8e1id819o.png)
![[A_t]=0.29M](https://img.qammunity.org/2021/formulas/chemistry/college/b2ap57gmw8hdlzaz373epkf65izfv6ufrh.png)
Therefore, the concentration of AB after 14.0 s is, 0.29 M