How many milliliters of 0.700 M HNO3 are required to reach the stoichiometric point of the reaction?

Question

Consider the titration of 300.0 mL of 0.700 M NH₃ (K_b = 1.8 ´ 10^–5) with 0.700 M HNO₃. How many milliliters of 0.700 M HNO₃ are required to reach the stoichiometric point of the reaction?

Answer 1

NH₃ + HNO₃ ==> NH4⁺ + NO3^-

1 mole HNO₃ required per mole NH₃ for neutralization

Since both NH₃ and HNO₃ are at the same molarity, and the stoichiometric ratio is 1:1, the volume of HNO₃ needed for neutralization will be the same as the volume of NH₃ = 300.0 mls. To show this mathematically...

moles NH₃ = 300.0 ml x 1 L/1000 ml x 0.700 mol/L = 0.210 moles NH₃

moles HNO₃ required = 0.210 moles

Volume HNO₃ required:

(x L)(0.700 mol/L) = 0.210 moles

x = 0.300 L = 300.0 mls