6.37 g of H3PO4 (molar mass 98 g mol^-1) is converted completely to Na2HPO4 by NaOH. Calculate the volume of 0.25 M NaOH required, in mL (nearest integer).

JEE Main levelNumerical answerDifficulty 2 of 3eq005

$6.37 g$ of $H X_{3} PO X_{4}$ (molar mass $98 g mo l^{- 1}$ ) is converted completely to $Na X_{2} HPO X_{4}$ by $NaOH$ . Calculate the volume of $0.25 M$ $NaOH$ required, in $mL$ (nearest integer).

Numerical answer type, answer in mL, tolerance 0.5.

For the change

H X_{3} PO X_{4} \to Na X_{2} HPO X_{4}

n = 2

. Moles of

H X_{3} PO X_{4} = 6.37/98 = 0.065

, so equivalents

= 2 \times 0.065 = 0.130

NaOH

has

n = 1

, so volume

= 0.130/0.25 = 0.52 L = 520 mL