Question

By titration, it is found that 47.5 mL of 0.146 M NaOH(aq) is needed to neutralize 25.0 mL of HCl(aq). Calculate the concentration of the HCl solution.

Answer 1

The correct answer is 0.277 M HCl

Step-by-step explanation:

NaOH is a strong base and HCl is a strong acid. NaOH reacts with HCl to form a salt (NaCl) and water via a neutralization reaction, as follows:

NaOH + HCl → NaCl + H₂O

At the equivalence point, the moles of NaOH added is equal to the moles of HCl present in the solution to be titrated. Moreover, the moles can be calculated as the product of the concentration of base or acid (Cb or Ca) and the volume (Vb and Va), as follows:

moles NaOH = moles HCl

Cb x Vb = Ca x Va

Thus, we calculate the concentration of HCl (Ca), as follows:

Ca = (Cb x Vb)/Va = (0.146 M x 47.5 mL)/(25.0 mL)= 0.277 M