If 30.0 mL of .50M KOH is neede to neutralize 10.0 mL of HCl of unknown concentration, what is the molarity of the HCl solution?

Answer 1

Hello, Nick,

The neutralization reaction is KOH + HCl = KCl + H₂O

Since this is an equi-molar reaction (1 molecule of KOH reacts with 1 molecule of HCl) we can use the relationship:

M1V1 = M2V2,

where M and V are molarity and volumes of the two reactants. Rearrange to find the unknown, M2

M2 = (M1V1)/V2

M2 = (30ml*0.50M)/(10.0ml)

M2 = 1.5M

This makes sense, since: M1V1 = (0.50 moles/L)*(0.03L) = 0.015 moles of KOH, and

M2V2 = (1.5M)*(0.010 L) = 0.015 moles of KOH

They are both 0.015 moles, for the calculated volumes.

Bob

Bob