Question

A 5.40 mL sample of an H3PO4 solution of unknown concentration is titrated with a 5.000×10−2 M NaOH solution. A volume of 7.02 mL of the NaOH solution was required to reach the equivalence point.

What is the concentration of the unknown H3PO4 solution?
Express your answer using four significant figures.

Answer 1

0.065 M

Step-by-step explanation:

Volume of H₃PO₄ solution (V1) = 5.40 mL

Volume of NaOH solution (V2) = 7.02 mL

Molarity of NaOH solution (M2) = 5 × 10⁻² M

Molarity of H₃PO₄ solution (M1) = ?

Solution:

It is a acid base titration

Formula to be used

M1V1 = M2V2

Put values in above equation

M1 x 5.40 mL = 5 × 10⁻² M x 7.02 mL

Rearrange the above equation

M1 = 5 × 10⁻² M x 7.02 mL / 5.40 mL

M1 = 0.065 M

So the Molarity H₃PO₄= 0.065 M