Question

A 59 mL sample of hydrobromic acid is titrated with 93 mL of a 3.5 M solution of strontium hydroxide to reach the equivalence point. What is the concentration of hydrobromic acid?

Answer 1

A 59 mL sample of hydrobromic acid is titrated with 93 mL of a 3.5 M solution of strontium hydroxide to reach the equivalence point. What is the concentration of hydrobromic acid?

We write reaction between HBr and Sr(OH)

Sr(OH)2 + 2 HBr --- > SrBr2 + 2 H2O

Mole ratio between HBr : Sr(OH)2 is 2 : 1

Calculation of moles of strontium hydroxide

Mol strontium hydroxide = Volume in L x molarity

=0.093 L x 3.5 M = 0.3255 mol Sr(OH)2

Mol HBr = 0.3255 mol Sr(OH)2 x 2 mol HBr / 1 mol Sr(OH)2 = 0.651 mol

[HBr]=mol / volume in L

= 0.651 mol / 0.059 L = 11.0 M

Molarity of HBr = 11.0 M