Answer to Question #92528 in Organic Chemistry for Lee

Question

A quality-control technician is testing the concentration of muriatic acid (hydrochloric acid) to check that the concentration is within certain limits. Calculate the concentration of the hydrochloric acid if a 15.0-mL sample is titrated with standard sodium carbonate solution. The titration required 10.00 mL of 0.350 mol/L sodium carbonate to neutralize the acid.

Answer 1

n(Na₂CO₃) = C(Na₂CO₃) × V(Na₂CO₃) = 0.350 mol/L × 0.010 L = 0.0035 mol.

0.0035 mol   X mol

    Na₂CO₃ + 2HCl = 2NaCl + H₂O + CO₂↑

     1 mol     2 mol

n(HCl) = X = 0.007 mol.

C(HCl) = n(HCl) / V(HCl) = 0.007 mol / 0.015 L = 0.4667 mol/L ≈ 0.467 mol/L.