The rate law for a hypothetical reaction is rate=k[a][b]. if the concentration of a and b are both 0.020 miles per liter and k = 1.3x10-1m-1s-1, what is the reaction rate

What you got here looks to be a plug-and-chug question
Note that mol/L = M

you know that
 
rate= k[a][b]

rate=?
k=1.3*10^-1 1/Ms
a=0.020 M
b=0.020 M

rate= (1.3*10^-1)(0.020)(0.020)= -->the units cancel out to give you M/s

rate= 0.000052 M/s

Rate = 1.3×10⁻¹×0.02×0.02 = 5.2×10⁻⁵ mole-L⁻¹-s⁻¹

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