Calculate the initial rate and the rate after 10 seconds

Question

For the gas phase reaction 2 NO₂ + F₂ -> 2 NO₂F, the rate constant is 38 dm³ mol^-1 s^-1 at 300K. The reaction is first order in F₂ and NO₂.

(a) Calculate the number of moles of NO₂, F₂, andNO₂F present after 10 S if 2.00 moles of NO₂ are mixed with 3.00 moles of F₂ in a 400 dm³ vessel at 300 K.

(b) Calculate the initial rate and the rate after 10 seconds for this mixture.