Use the formula for second order reaction:
[tex]\frac{1}{C} = \frac{1}{C_0} + kt[/tex]
C = concentration at time t
C0 = initial conc.
k = rate constant
t = time
1st equation : [tex]\frac{1}{0.56} = \frac{1}{C_0} + 115k[/tex]
2nd Equation: [tex]\frac{1}{0.033} = \frac{1}{C_0} + 735k[/tex]
Find [tex] \frac{1}{C_0} [/tex] from 1st equation and put it in 2nd equation:
[tex]\frac{1}{0.033} = \frac{1}{0.56} - 115k + 735k[/tex]
[tex]\frac{1}{0.033} - \frac{1}{0.56} = 620k [/tex]
k = 0.046
