Final answer:
The new rate of the reaction is 1.377 x 10-8 mol/L.s.
Step-by-step explanation:
To calculate the new rate of the reaction, we can use the rate equation:
rate = k[NH4+][NO2-]
Substituting the given values, the initial rate is 5.4 x 10-7 mol/L.s when [NH4+] = 0.0100 mol/L and [NO2-] = 0.200 mol/L.
Now, we can calculate the new rate using the new concentrations:
rate = k[NH4+][NO2-] = (5.4 x 10-7 mol/L.s)(0.100 mol/L)(0.255 mol/L) = 1.377 x 10-8 mol/L.s