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Stoichiometry

25 mL of 0....

Question

$25 m L$ of $0.107 M H_{3} P O_{4}$ was titrated with $0.115 M$ solution of $N a O H$ to the end point identified by indicator bromocresol green. This required $23.1 m L$ The titration was repeated using phenolphthalein as indicator. This time $25 m L$ of $0.107 M H_{3} P O_{4}$ required $46.2 m L$ of the $0.115 M N a O H$ . What is the coefficient $^{'} n^{'}$ in the following reaction?
$H_{3} P O_{4} + n O H^{-} \to [H_{3 - n} P O_{4}]^{n -} + n H_{2} O$ .

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Solution

Number of milliequivalents of $H_{3} P O_{4}$
$= 25 \times 0.107 \times n$
$= 2.675 \times n$
In first titration: Number of milliequivalents of $O H^{-}$ used
$= 23.1 \times 0.115 \times 1 = 2.66$
(Acidity of $N a O H = 1)$
In second titration: Number of milliequivalent of $O H^{-}$ used
$= 46.2 \times 0.115 \times 1 = 5.313$
$∴$ In first titration: $2.675 \times n = 2.66$
i.e., $n = 1$
$∴$ In second titration: $2.675 \times n = 5.313$
$n = 2$ .

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Similar questions

25 m L

0.107

H_{3} {P O}_{4}

was titrated with

0.115 M

N a O H

to the endpoint identified by indicator bromocresol green. This required

23.1 m L

0.115 M

N a O H

. The titration was repeated using phenolphthalein as an indicator. This time

25 m L

0.107 M

H_{3} {P O}_{4}

46.2 m L

0.115 M

N a O H

. What is the coefficient of

n

in this equation for each reaction?

H_{3} {P O}_{4} + n {O H}^{-} ⟶ n H_{2} O + {[H_{3 - n} {P O}_{4}]}^{n -}

25 m L

of a mixture of

N a O H

N a_{2} C O_{3}

when titrated with

N / 10 H C l

using phenolphthalein indicator required

25 m L H C l

. The same volume of mixture when titrated with

N / 10 H C l

using methyl orange indicator required

30 m L

H C l

. Calculate the amount of

N a_{2} C O_{3}

N a O H

in one litre of this mixture.

25 m L

of a mixture of

N a O H + N a_{2} C O_{3}

, when titrated with

\frac{N}{10} H C l

using phenolphthalein indicator required

25 m L H C l

to decolourise phenolphthalein. At this stage, methyl orange was added and the addition of acid was continued. The second endpoint was reached after further addition of

5 m L

of the acid. Calculate the amount of

N a_{2} C O_{3}

N a O H

in one litre of the solution.

500 m L

of a solution of

C a C O_{3}

N a O H

was first titrated with

\frac{N}{10} H C l

using phenolphthalein indicator.

18.5 m L

H C l

was required for the end point. After that methyl orange indicator was used and

2.5 m L

H C l

was required for the next end point. Find out the mass of

C a C O_{3}

in the mixture.

500 m L

of a solution of

C a C O_{3}

N a O H

was first titrated with

\frac{N}{10} H C l

using phenolphthalein indicator.

18.5 m L

H C l

was required for the end point. After that methyl orange indicator was used and

2.5 m L

H C l

was required for the next end point. Find out the mass of

C a C O_{3}

in the mixture.

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