Question

The concentration of a certain sodium hydroxide solution was determined by using the solution to titrate a sample of potassium hydrogen phthalate (KHP).

In the titration, 20.46 mL of the NaOH solution was required to react with 0.1082g KHP.

Calculate the molarity of the base.

Answer 1

[ NaOH ] = 0.026 M

Step-by-step explanation:

• molarity NaOH = mol NaOH / Vsln(L)

∴ Vsln = 20.46 mL = 0.02046 L

• NaOH(aq) + KHC8H4O4(aq) → KNaC8H4O4(aq) + H2O(l)

∴ Mw KH(KHC8H4O4) = 204.24 g/mol

⇒ mol KHP = 0.1082 g / 204.24 g/mol = 5.298 E-4 mol

⇒ mol NaOH = (5.298 E-4 mol KHP)( mol NaOH/mol KHP)

⇒ mol NaOH = 5.298 E-4 mol

⇒ [ NaOH ] = 5.298 E-4 mol / 0.02046 L

⇒ [ NaOH ] = 0.026 mol/L = 0.026 M