A solution is 0.20 M Ba(OH)₂. How many moles of H+ must be added to neutralize 100.0 mL of the solution? A) 0.020 mol B) 0.080 mol C) 0.040 mol D) 0.40 mol E) 0.80 mol

Question

Quizplus · Accepted Answer

Ba(OH)2 is a strong base and fully dissociates in water to form OH- ions. Therefore, the number of moles of OH- ions in 100.0 mL of the solution is:

0.20 mol/L x 0.100 L = 0.020 mol

Since Ba(OH)2 has a 1:2 ratio of OH- to Ba2+ ions, there are 0.010 mol of Ba2+ ions in 100.0 mL of the solution. To neutralize these ions, an equal number of H+ ions must be added. Since H+ ions do not exist on their own in solution, they must be added in the form of an acid. The most common acid used for neutralization is HCl. The balanced chemical equation for the neutralization reaction is:

Ba(OH)2 + 2HCl → BaCl2 + 2H2O

From the balanced equation, it can be seen that for every 1 mole of Ba(OH)2, 2 moles of HCl are required. Therefore, to neutralize 0.010 mol of Ba2+ ions, 0.020 mol of H+ ions are required. This is equivalent to adding:

0.020 mol/L x 0.100 L = 0.0020 mol

of HCl to the solution. However, the question asks for the number of moles of H+ ions required, not the amount of HCl. Since 1 mole of HCl produces 1 mole of H+ ions, the number of moles of H+ ions required is also 0.0020 mol. Therefore, the correct answer is C) 0.040 mol.

A Solution Is 0