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Byju's Answer

Standard XII

Chemistry

Ellingham Diagram

An aqueous so...

Question

An aqueous solution of $K I O_{3}$ and $K I$ on mixing undergoes redox process to give $I_{2}$ . The reaction occurs quantitatively and can be used to estimate the conc. of $K I O_{3}$ . The iodine liberated in the reaction can be estimated by using hypo solution and starch as indicator.
If $x$ millimoles of $K I O_{3}$ react completely with $y$ millimoles of $K I$ , then which of the following are correct?

x > y

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y > x

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x = 5 y

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y = 5 x

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Solution

The correct options are
B $y > x$
D $y = 5 x$
Balanced redox reaction between $K I O_{3}$ and $K I$ is as follows:
$6 H C l + K I O_{3} + 5 K I \to 3 I_{2} + 3 H_{2} O + 16 K C l$
Generally, $5$ moles of $K I (y)$ reacts with $1$ mole of $K I O_{3} (x)$ .
It means $y > x$ and $y$ should be $5$ times of $x$ .
Hence, options B and D are correct.

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Similar questions

Q. In an iodometric estimation, the following reactions occur

2 C u^{2 +} + 4 I^{-} \to C u_{2} I_{2} + I_{2}; I_{2} + 2 N a_{2} S_{2} O_{3} \to 2 N a I + N a_{2} S_{4} O_{6}

0.12 m o l e

C u S O_{4}

was added to excess of

K I

solution and the liberated iodine required

120 m L

of hypo. The molarity of hypo solution was:

Q. An aqueous solution containing 0.10 g

K I O_{3}

(formula wt. = 214.0) was treated with an excess of KI solution. The solution was acidified with HCl. The liberated

I_{2}

consumed 45.0 ml of thiosulphate solution to decolourise the blue starch - iodine complex. Calculate the molarity of the sodium thiosulphate solution.

Q. An aqueous solution containing

0.10

K I O_{3}

(formula weight

= 214.0

) was treated with an excess of

K I

solution. The solution was acidified with

H C l

. The liberated

I_{2}

consumed

45.0

mL of thiosulphate solution to decolourise the blue starch iodine complex. Calculate the molarity of the sodium thiosulphate solution.

Q. An aqueous solution containing

0.10 g K I O_{3} (formula weight = 214.0 g / m o l)

was treated with an excess of

K I

solution. The solution was acidified with

H C l .

The liberated

I_{2}

consumed

55 m L

of thiosulphate solution to decolourise the blue starch-iodine complex. Calculate molarity of the sodium thiosulphate solution.

Q. Assertion :

K I O_{3}

reacts with

K I

to liberate iodine which is titrated with standard hypo solution. The reactions are:
(i)

I O_{3}^{-} \to I_{2}

(Valency factor = 5/3)
(ii)

I_{2} + S_{2} O_{3}^{2} \to S_{4} O_{6}^{2 -} + I^{-}

(Valence factor

=

2)
Milliequivalent of hypo

=

meq. of

I_{2} =

meq. of

I O_{3}^{-}

Milliequivalent of hypo =

2 \times m e q .

I O_{3}^{-} =

meq. of

I^{-}

Reason: Valency factor of

I_{2}

in both the equation are different, therefore we cannot compare milliequivalents in sequence.

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The correct options are B y>x D y=5xBalanced redox reaction between KIO3 and KI is as follows:6HCl+KIO3+5KI→3I2+3H2O+16KClGenerally, 5 moles of KI (y) reacts with 1 mole of KIO3 (x).It means y>x and y should be 5 times of x.Hence, options B and D are correct.