Chlorine (7.1 g) is passed into hot concentrated NaOH, where it is converted completely into chloride and chlorate: Cl2 + OH^- -> Cl^- + ClO3^- + H2O. Balance the equation and calculate the mass of NaClO3 formed. Atomic masses: Na 23, Cl 35.5, O 16 (so Cl2 = 71 g/mol). Give the answer in grams to two decimal places.

JEE Advanced levelNumerical answerDifficulty 3 of 3rx064

Chlorine (7.1 g) is passed into hot concentrated NaOH, where it is converted completely into chloride and chlorate: $Cl X_{2} + OH X^{-} Cl X^{-} + ClO X_{3} X^{-} + H X_{2} O$ . Balance the equation and calculate the mass of $NaClO X_{3}$ formed. Atomic masses: Na 23, Cl 35.5, O 16 (so $Cl X_{2}$ = 71 g/mol). Give the answer in grams to two decimal places.

Numerical answer type, answer in g, tolerance 0.02.

The balanced equation is

3 Cl X_{2} + 6 OH X^{-} 5 Cl X^{-} + ClO X_{3} X^{-} + 3 H X_{2} O

(5 Cl reduced, 1 Cl oxidised by 5 electrons). n(

Cl X_{2}

) = 7.1/71 = 0.10 mol, so n(

ClO X_{3} X^{-}

) = 0.10/3 = 0.0333 mol. Molar mass of

NaClO X_{3}

= 23 + 35.5 + 48 = 106.5 g/mol, so mass = 3.55 g.