Question

titration 25.0 ml of 3.4 x 10^ -3 M of Ba(OH) Neutralize 16.6 mL of HCL solution. What is the molarity of HCL solution?

Answer 1

What we  are give: Concentration of base (CB) = 3.4 × $10^{-3}$
Then convert all volume in ml to L.
Volume of base (VB) 25.0ml = 0.025L
Volume of acid (VA) 16.6ml = 0.0166L
Now that we have everything we use the formula CAVA=CBVB.
Make 'CA' the subject then solve. 
CA=$\frac{CBVB}{VA}$