2.In a titration, 25.00 cm3 of a solution of hydrochloric acid reacted with 18.40 cm3 of sodium hydroxide solution of concentration 0.15 mol/dm3. The equation which represents the reaction is:
HCl + NaOH > NaCl + H2O
Calculate the concentration of hydrochloric acid in mol/dm3

0.11mol/dm³

Explanation:

The reaction expression is given as:

             HCl   +  NaOH  →  NaCl + H₂O

Volume of acid  = 25cm³  = 0.025dm³

Volume of base  = 18.4cm³ = 0.0184dm³

Concentration of base  = 0.15mol/dm³

Solution:

The concentration of hydrochloric acid = ?

 To solve this problem, let us first find the number of moles of the base;

 Number of moles  = concentration x volume

 Number of moles  = 0.15mol/dm³ x 0.0184dm³  = 0.00276mol

From the balanced reaction equation;

          1 mole of NaOH will combine with 1 mole of HCl

Therefore,  0.00276mol of the base will combine with  0.00276mol of HCl

 So;

  Concentration of acid  =   =   = 0.11mol/dm³