Question

An aqueous solution of barium hydroxide is standardized by titration with a 0.167 M solution of perchloric acid. If 12.8 mL of base are required to neutralize 25.4 mL of the acid, what is the molarity of the barium hydroxide solution?

Answer 1

• 0.166M

Step-by-step explanation:

1. Barium hidroxide

Barium hydroxide is a strong base that ionizes as per the equation:

`Ba(OH)_2\rightarrow Ba^(+2)+2OH^-`

Thus, every mole of Ba(OH)₂ yields 2 moles of OH⁻.

2. Perchloric acid

Perchloric acid is a strong acid whose ionization may be represented by the following chemical equation:

`HClO_4\rightarrow H^+ClO_4^-`

Thus, every mole of HClO₄ yields 1 mole of H⁺.

3. Calculate the number of moles of perchloric acid and H⁺:

• #moles of HClO₄ = Molarity × Volume in liters

• #moles HClO₄ = 0.167M × 25.4mL × 1L / 1,000m: = 0.0042418‬mol

The number of moles of H⁺ is equal to the number of moles of HClO₄

• #moles of H⁺ = 0.0042418 mol

4. Calculate the number of moles of Ba(OH)₂

When the solution is neutralized the number of moles of OH⁻ is equal to the number of moles of H⁺

• #moles of OH⁻ = 0.0042418

The number of moles of Ba(OH)₂ is half of the number of moles of OH⁻:

• #moles of Ba(OH)₂ = 0.0042418/2 = 0.0021209 mol Ba(OH)₂

5. Calculate the molarity of the Ba(OH)₂ solution:

• Molarity = number of moles / volume in liters

• Molarity = 0.0021209mol / 0.0128liters = 0.16569 ≈ 0.166M