First, we write the reaction equation between hydrochloric acid sodium hydroxide.
HCl + NaOH → NaCl + H₂O
From this, we can see that the molar ratio between HCl and NaOH is 1 : 1.
We also know that:
Moles = concentration * volume
Therefore, we may equate the produce of each substance's concentration and volume:
M₁V₁ = M₂V₂
M₁ = (0.25 * 22.5)/10
M₁ = 0.56 M
The hydrochloric acid is 0.56 moles per liter.
