A chemist needs to determine the concentration of a solution of nitric acid, HNO_3. She puts 865 mL of the acid in a flask along with a few drops of indicator. She then slowly adds 0.800 M Ba(OH)_2 to the flask until the solution turns pink, indicating the equivalence point of the titration. She notes that 165 mL of Ba(OH)_2 was needed to reach the equivalence point.
How many moles of Ba(OH)_2 are present in 165 mL of 0.800 M Ba(OH)_2?
Express your answer with the appropriate units.