HARD

Earn 100

A 3.00 g sample containing Fe₃O₄, Fe₂O₃ and an inert impure substance, is treated with excess of KI solution in presence of dilute H₂SO₄. The entire iron is converted into Fe²⁺ along with the liberation of iodine. The resulting solution is diluted to 100 mL . A 20 mL of the diluted solution requires 11.0 mL of 0.5 M Na₂S₂O₃ solution to reduce the iodine present. A 50 mL of the dilute solution, after complete extraction of the iodine required 12.80 mL of, 0.25 M KMnO₄ solution in dilute H₂SO₄ medium for the oxidation of Fe²⁺. Calculate the percentage of inert impurity in original sample to the nearest whole number.

50% studentsanswered this correctly

Important Questions on Redox Reactions

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

Given below are two statements:
Statement I : In the titration between strong acid and weak base methyl orange is suitable as an indicator.
Statement II : For titration of acetic acid with $\mathrm{NaOH}$ phenolphthalein is not a suitable indicator.
In the light of the above statements, choose the most appropriate answer from the options given below:

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

Identify the correct statements from the following.
i.In

{[CoCl {({NH}_{3})}_{5}]}^{2 +},

the Lewis acid is

{Co}^{3 +}

ii. An example for heteroleptic complex is

{[Co {({NH}_{3})}_{6}]}^{3 +}

iii. The hybridisation of

Mn

{[{MnBr}_{4}]}^{2 -}

{dsp}^{2}

iv. In

[Ni (CO)_{4}],

the metal-carbon bond possesses

σ

and

π

character.

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

In a titration experiment, $10 mL$ of an ${FeCl}_{2}$ solution consumed $25 mL$ of a standard $K_{2} {Cr}_{2} O_{7}$ solution to reach the equivalent point. The standard $K_{2} {Cr}_{2} O_{7}$ solution is prepared by dissolving $1.225 g$ of $K_{2} {Cr}_{2} O_{7}$ in $250 mL$ water. The concentration of the ${FeCl}_{2}$ solution is closest to

[Given : molecular weight of $K_{2} {Cr}_{2} O_{7} = 294 g {mol}^{- 1}$ ]

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

Excess of acidic solution of

KI

to mixed with

25 mL

H_{2} O_{2}

. Liberated

I_{2}

requires

20 mL

0.3 N {Na}_{2} S_{2} O_{3}

solution. The volume strength of

H_{2} O_{2}

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

An alkali is titrated against acid with methyl orange as an indicator, which of the following is a correct combination?

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

Number of moles of dichromate needed to oxidise one mole of

{Sn}^{2 +}

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

2 {KMnO}_{4} + 3 H_{2} {SO}_{4} + 5 H_{2} O_{2} \to K_{2} {SO}_{4} + 2 {MnSO}_{4} + 8 H_{2} O + 5 O_{2}

Find the nonnality of

H_{2} O_{2}

solution, if

20 mL

of it is required to react completely with

16 mL

0.02 {MKMnO}_{4}

solution. ( Molar mass of

{KMnO}_{4} = 158 g {mol}^{- 1}

)

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

In Tollen's test for aldehyde, the overall number of electron(s) transferred to the Tollen's reagent formula

{[Ag {({NH}_{3})}_{2}]}^{+}

per aldehyde group to form silver mirror is ___.(Round off to the Nearest integer)

EASY

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

While titration dilute

HCl

solution with aqueous

NaOH

, which of the following will not be required ?

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

In the titration of

I_{2} (aq)

S_{2} O_{3}^{2 -}

(aq)

using the starch indicator, the end point is indicated by:

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

For kinetic study of the reaction of iodide ion with $H_{2} O_{2}$ at room temperature :

(A) Always use freshly prepared starch solution.

(B) Always keep the concentration of sodium thiosulphate solution less than that of $KI$ solution.

(D) Record the time immediately before the appearance of blue colour.

(E) Always keep the concentration of sodium thiosulphate solution more than that of $KI$ solution.

Choose the correct answer from the options given below

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

50 mL

0 .5 M

oxalic acid is needed to neutralize

25 mL

of sodium hydroxide solution. What is the amount of

NaOH

50 mL

of the given sodium hydroxide solution?

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

To measure the quantity of

{MnCl}_{2}

dissolved in an aqueous solution, it was completely converted to

{KMnO}_{4}

using the reaction,

{MnCl}_{2} + K_{2} S_{2} O_{8} + H_{2} O \to {KMnO}_{4} + H_{2} {SO}_{4} + HCl

(equation not balanced). Few drops of concentrated

HCl

were added to this solution and gently warmed. Further, oxalic acid

(225 mg)

) was added in portions till the colour of the permanganate ion disappeared. What is the quantity of

{MnCl}_{2}

(in mg) present in the initial solution? (Atomic weights in

g {mol}^{- 1} : Mn = 55, Cl = 35 .5

)

EASY

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

In the given chemical reaction, colors of the ${Fe}^{2 +}$ and ${Fe}^{3 +}$ ions, are respectively :

$5 {Fe}^{2 +} + {MnO}_{4}^{-} + 8 H^{+} \to {Mn}^{2 +} + 4 H_{2} O + 5 {Fe}^{3 +}$

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

0.4 g

mixture of

NaOH, {Na}_{2} {CO}_{3}

and some inert impurities was first titrated with

\frac{N}{10} HCl

using phenolphthalein as an indicator,

17.5 mL

HCl

was required at the end point. After this methyl orange was added and titrated.

1.5 mL

of same

HCl

was required for the next end point. The weight percentage of

{Na}_{2} {CO}_{3}

in the mixture is (Rounded-off to the nearest integer)

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

0.01 {MKMnO}_{4}

solution was added to

20.0 mL

0.05 M Mohr

's salt solution through a burette. The initial reading of

50 mL

burette is zero. The volume of

{KMnO}_{4}

solution left in the burette after the end point is.......

mL

. (nearest integer)

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

2.0 g

sample containing

{MnO}_{2}

is treated with

HCl

liberating

{Cl}_{2}

. The

{Cl}_{2}

gas is passed into a solution of

KI

and

60.0 mL

0.1 {MNaS}_{2} O_{3}

is required to titrate the liberated iodine. The percentage of

{MnO}_{2}

in the sample is____. Nearest integer)
[Atomic masses (in

u

)

Mn = 55; Cl = 35.5 : O = 16, I = 127, Na = 23, K = 39, S = 32

]

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

The volume of

0.1 {MKMnO}_{4}

solution required to completely react with a solution obtained by dissolving

0.63 g

of oxalic acid (molar mass

126 {gmol}^{- 1})

50 mL

distilled water in acidic medium in

mL

HARD

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

In a complexometric titration of metal ion with ligand

M (M e t a l i o n) + L (L i g a n d) \to C (C o m p l e x)

end point is estimated spectrophotometrically (through light absorption). If 'M' and 'C' do not absorb light and only 'L' absorbs then the titration plot between absorbed light

(A)

versus volume of ligand 'L'

(V)

would look like:

MEDIUM

Chemistry>Physical Chemistry>Redox Reactions>Volumetric Analysis

A mixture of

2.3 g

formic acid and

4.5 g

oxalic acid is treated with concentrated

H_{2} {SO}_{4}

. The evolved gaseous mixture is passed through

KOH

pellets. What will be the weight in grams of the remaining product at

STP

Important Questions on Redox Reactions

Learn and Prepare for any exam you want !