A nitric acid solution is found to have a pH of 2.70. Determine each of the following:

a. [H3O] <-2.0 x 10^-3 M (antilog(-pH))

b.[OH] <-5.0 x 10^-12 M (1.0 x 10^-14/2.0 x 10^-3)

c. The number of moles of HNO3 required to prepare 5.50L of this solution.

moles=concentration x volume right? So (2.0 x 10^-3 M) x 5.50 L = 1.1 x 10^-2 moles

d. The mass of the moles of HNO3 in the solution in part c.

1 mole of HNO3=63.01g/mole

1.1 x 10^-2 moles x 63.01 g/mole = 6.93 x 10^-1 grams right?

e.The milliliters of concentrated acid needed to prepare the solution in part c. (Concentrated nitric acid is 69.5% HNO3 by mass and has a density of 1.42 g/mL.)

I have literally no idea of how to do this one, any tips would be helpful and appreciated. (: