Final answer:
The molarity of NO₃ in the solution after mixing, assuming the volumes are additive, is 0.268 M. This is determined using the concept of molarity and volume addition, with the result being the same as the original solution.
Step-by-step explanation:
In order to determine the concentration of [NO₃] in the solution after mixing, it's critical to understand the concept of molarity and volume addition. Since the original solution of KNO₃ has a molarity of 0.268 M and the volume of this solution is 300 mL, the number of moles of KNO₃ (and therefore of NO₃, as there's one unit of NO₃ in each unit of KNO₃) in the original solution can be calculated using the formula Molarity = Moles ÷ Volume. Therefore the Moles of NO₃ = Molarity x Volume = 0.268 mol/L x 0.3 L = 0.0804 mol. As the solution is still the same after addition of the volumes, based on the question where the volumes are additive, the molarity of the resulting solution will be the same 0.268 Mol.
Learn more about [NO₃] Concentration