Consider the following elementary reaction: NO2(g) + F2(g) --> NO2F(g) + F (g) Suppose we let k1 stand for the rate constant of this reaction, and k -1 stand for the rate constant of the reverse reaction. Write an expression that gives the equilibrium concentration of F2 in terms of k1, k -1, and the equilibrium concentrations of NO2, NO2F, and F.