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The pink colour of phenolphthalein in alkaline medium is due to

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Important Questions on Equilibria

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Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

In base vs. Acid titration, at the end point methyl orange is present as

HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

The Plot of

pH

-metric titration of weak base

{NH}_{4} OH

vs strong acid

HCl

looks like

EASY

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

100 mL

0.1 M HCl

is taken in a beaker and to it

100 mL

0.1 M NaOH

of is added in steps of

2 mL

and the

pH

is continuously measured. Which of the following graphs correctly depicts the change in

pH

HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

A compound '

X

' is a weak acid and it exhibits colour change at

pH

close to the equivalence point during neutralization of

NaOH

with

{CH}_{3} COOH

. Compound '

X

' exists in ionized form in basic medium. The compound '

X

' is

HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

In an acid-base titration,

0.1 M H C l

solution was added to the

N a O H

solution of unknown strength. Which of the following correctly shown the change of

p H

of the titration mixture in this experiment?
Question Image

EASY

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

100 m l

solution of

0.1 N H C l

was titrated with

0.2 N N a O H

solution. The titration was discontinued after adding

30 m l

N a O H

solution. The remaining titration was completed by adding

0.25 N K O H

solution. The volume of

K O H

required for completing the titration is

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Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

The equivalent masses of

N a_{2} C O_{3}

when it is titrated with

H C l

using phenolphthalein and methyl orange separate experiments are

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Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

Titration curves for $0.1 M$ solutions of three weak acids $HA, {HA}_{2}$ and ${HA}_{3}$ with ionization constants $K_{1}, K_{2}$ and $K_{3}$ respectively are plotted as shown in the figure. Which of the following is/are true?

Question Image

HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

Which one is the correct graph (figure) for the corresponding acid base titration?

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Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

A solution contains Na₂CO₃ and NaOH with Phenolphthalein as indicator, 25 mL of a mixture requires 19.5 mL of 0.005 N HCl for the end point. If methyl orange is indicator, then 25 mL of solution requires 25.9 of the same HCl for end point. Then concentration of NaOH substance in original solution is:

EASY

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

The titration curve for titration of a $50 mL$ solution of a diprotic acid with $0.1 M NaOH$ is shown below.

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$K_{a 1}$ and $K_{a 2}$ are approximately

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Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

Phenolphthalein is not a good indicator for titrating

EASY

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

100 m L

of a mixture of

N a O H

and

{N a}_{2} {S O}_{4}

is neutralized by

10 m L

0.5 M H_{2} {S O}_{4}

. The amount of

N a O H

100 m L

solution is -

HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

The curve in the figure shows the variation of the

pH

during the course of the titration of a weak acid

HA

, with a strong base (

NaOH

). At which point in the titration curve is the concentration of the acid equal to that of its conjugate base?

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HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

4.08 g of a mixture of BaO and unknown carbonate MCO₃ was heated strongly. The residue weighed 3.64 g. This was dissolved in 100 mL of 1 N HCl. The excess acid required 16 mL of 2.5 N NaOH solution for complete neutralisation. Identify the metal M.

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Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

Represent the union of two sets by Venn diagram for each of the following.

$X = {x | x$ is a prime number between $80$ and $100}$

$Y = {y | y$ is an odd number between $90$ and $100}$

HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

When

20 mL

0.2 M HBrO

is titrated with

0.10 M NaOH

(K_{a} = 2.3 \times 10^{- 9} M)

. Find
(i)

pH

before titration.
(ii)

pH

when

[HBrO] = [{BrO}^{-}]

.
(iii)

pH

at point of equivalence.
(iv) When are moles of

{OH}_{aq}^{-}

twice the moles of

HBrO

originally present?

MEDIUM

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

The following graph represents the titration of

pH Vs volume of NaOH for

HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

In a double titration method, for the mixture of NaHCO₃ and Na₂CO₃, the volume of HCl used at phenolphthalein indicator end point was x ml and further of Methyl orange indicator end point was y ml. The volume of HCl for complete reaction of NaHCO₃ is -

HARD

Chemistry>Physical Chemistry>Equilibria>Indicators and Acid-base Titrations

Mixture of 1 g each of Na₂CO₃ and NaHCO₃ is reacted with 0.1 N HCl. The quantity of 0.1 M HCl required to react completely with the above mixture is

The pink colour of phenolphthalein in alkaline medium is due to

Important Questions on Equilibria

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