A 0.105 L sample of an unknown HNO3 solution required 41.1 mL of 0.150 M Ba(OH)2 for complete neutralization. What is the concentration of the HNO3 solution?

Question

Balanced Equation:

2HNO3(aq)+Ba(OH)2(aq)⟶2H2O(l)+Ba(NO3)2(aq)

Answer 1

0.150M Ba(OH)₂ means the solution contains 0.150 moles/liter of Ba(OH)₂ and considering there is 41.1 mL of it, or, in other words, 0.0411 liters of it, then there are (0.150 moles/liter)•(0.0411 liters) = 0.006165 moles of Ba(OH)₂

Using the balanced chemical reaction equation:

2HNO₃(aq) + Ba(OH)₂(aq) ⟶ 2H₂O(l) + Ba(NO₃)₂(aq)

we see that for every 1 mole of Ba(OH)₂ we need 2 moles of HNO₃ meaning there must be 2(0.006165) = 0.01233 moles of HNO₃

Since there are 0.01233 moles of HNO₃ in the solution and there is 0.105 liters of that solution, then the concentration is (0.01233 moles)/(0.105 liters) = 0.117 moles/liter = 0.117 M solution of HNO₃