Question

A 25.0 ml sample of an hcl solution is titrated with a 0.139 m naoh solution. the equivalence point is reached with 15.4 ml of base. the concentration of hcl is __________ m.

Answer 1

the balanced equation for the acid base reaction is as follows

NaOH + HCl ---> NaCl + H₂O

stoichiometry of NaOH to HCl is 1:1

the number of NaOH moles is - 0.139 mol/L x 0.0154 L = 0.00214 mol

the number of NaOH moles reacted = number of HCl moles reacted

therefore number of HCl moles reacted = 0.00214 mol

volume of HCl containing 0.00214 mol - 25.0 mL

number of HCl moles in 25.0 mL - 0.00214 mol

therefore number of HCl moles in 1000 mL - 0.00214 mol / 25.0 mL x 1000 mL/L

molarity of HCl is 0.0856 mol/L

concentration of HCl is 0.0856 M

Answer 2

The answer is 0.0856 M but I have no idea how to get theanswer. My attempt: HCl +NaOH --> NaCL + H2O I x .139M -- C -- E .0021406