The molarity of the hydrochloric acid is 0,125 M

»EXPLANATION«

In this case, you can use 2 ways to solve it: first, stoichiometrically, by first making a balanced reaction and then using moles to calculate molarity (mol/L); and second, which is simpler. Use the formula below:

Va × Ma × a = Vb × Mb × b

where Va is the volume of the acid, Ma is the molarity of the acid, and a is the valence of the acid; the same goes for bases.

Hydrochloric acid (HCl) and sodium hydroxide (NaOH) each have one valence. So, the calculation:

Va × Ma × a = Vb × Mb × b

20.0 cm³ × Ma × 1 = 25.0 cm³ × 0,1 M

20 cm³ × Ma × 1 = 2,5 mmol

Ma = 0,125 M

#GeniuzS05

#SAYIDI