When the acid and base react in a 1:1 ratio, the above equation (found in Table T of the reference tables) can be used to determine the unknown concentration.

HCl + NaOH --> H2O + NaCl

Let’s consider that 45.6ml of 1.25 M sodium hydroxide has been used to neutralize 20ml of hydrochloric acid. The concentration of HCl is then given by,

45.6  X  1.25 = 20.0 * molarity of analyte.

Solving the above equation will yield the concentration of the analyte.