The titration of 10.00 mL of an HCl solution of unknown concentration requires 120.54 mL of a 0.100 M NaOH solution to reach the equivalence point. What is the concentration of the unknown HCl solution?

Acid-base titration is a type of qualitative analysis in which the concentration of the unknown acid/base is determined by treating it with a known concentration of base/acid. Indicators are used to determine the end point or the equivalence point (when all the acid/base is neutralized by base/acid).

At the end point,

Moles of acid = Moles of base

Since,

Molarity of a solution is given by the moles of solute per liter of the solution

i.e.,

Molarity = moles of solute / volume of solution (in L)

moles = Molarity * Volume

moles = M * V

M₁V₁ ( acid )= M₂V₂( base )

Where,

M₁ is the molarity of the acid

V₁ is the volume of the acid

M₂ is the molarity of the base

V₂ is the total volume of the base

From the question,

M₁ = ?

M₂ = 0.100 M

V₁ = 10.00 mL

V₂ = 120.54 mL

Using the above mentioned formula

M₁V₁ ( acid )= M₂V₂( base )

M₁ * 10.00mL = 0.100 M * 120.54 mL

M₁ = 1.2054 M

Hence, the concentration of of HCl is 1.2054 M