By titration it is found that 38.1 ml of 0.147 m naoh (aq) is needed to neutralize 25.0 ml of hcl (aq). calculate the concentration of the hcl solution.

You must know what reaction happens during titration:

HCl + NaOH - - > NaCl + H₂O

So, the ratio for HCl to NaOH is 1:1.

The solution is as follows:

Concentration of HCl = Moles HCl/L solution

Concentration = (0.147 M NaOH) (0.0381 L) (1mol HCl/1 mol NaOH) / 0.025 L

Concentration = 0.224 M HCl