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A Certain monoprotic acid (weak) serves...

A Certain monoprotic acid (weak) serves as indicator . Assuming that colour change is seen when `1//3^(rd)` of the indicator has been converted to ions and that at end point the pH of solution is 6 , what is the value of `pK_(In)` ?

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AI Generated Solution

To solve the problem, we will use the Henderson-Hasselbalch equation, which is given by: \[ \text{pH} = \text{pK}_{\text{In}} + \log \left( \frac{[\text{In}^-]}{[\text{HIn}]} \right) \] Where: - \(\text{In}^-\) is the ionized form of the indicator (the conjugate base), ...
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An indicator has pK_(In)=5.3 . In a certain titration, this indicator is found to be 80% ionized in its acid form. Thus, pH of the solution is

An indicator is a weak acid and pH range of its colour is 3 to 5 . If the neutral point of the indicator lies in the centre of the [H^(+)] corresponding to given pH range, then pH at the equivalence point is

A 0.015 M solution of a weak acid has a pH of 3.52 . What is the value of the K_a for this acid?

(a) Define a universal indicator. Mention its one use. (b) Solution A gives pink colour when a drop of phenolphthalein indicator is added to it. Solution B gives red colour when a drop of methyl orange is added to it. What type of solutions are A and B which one of the solutions A and B will have a higher pH value ? (c) Name one salt whose solutions has pH more than 7 and one salt whose solution has pH less than 7.

Acid-base indicator such as methy 1 orange, phenolphthalein, and bromothymol blue ate substances which change colour accroding to the hydrogen ion concentration of the solution to which they are added. Most indicators are weak acids (or more rarely weak base) in which the undissociated and dissociated forms have different and distinct colours. If methy 1 orange is used as the examples and the un-dissociated forms is written as HMO , then dissociation occurs as shown below: Reaction: {:(HMOhArr,H^(o+)+,MO^(Theta),,),(Red,"Colourless","Yellow",,):} The indicator should have a sharp colour change with the equivalence point of the titration. Usually the colour change of the indicator occurs over a range of about two pH units. It should be noted that the eye cannot detect the exact end point of the tiytration. The pK_(a) of the indicator should be near the pH of the solution at the equivalance point. Which of the following sitution exists at the equivalence point of titration?

Acid-base indicator such as methy 1 orange, phenolphthalein, and bromothymol blue ate substances which change colour accroding to the hydrogen ion concentration of the solution to which they are added. Most indicators are weak acids (or more rarely weak base) in which the undissociated and dissociated forms have different and distinct colours. If methy 1 orange is used as the examples and the un-dissociated forms is written as HMO , then dissociation occurs as shown below: Reaction: {:(HMOhArr,H^(o+)+,MO^(Theta),,),(Red,"Colourless","Yellow",,):} The indicator should have a sharp colour change with the equivalence point of the titration. Usually the colour change of the indicator occurs over a range of about two pH units. It should be noted that the eye cannot detect the exact end point of the tiytration. The pK_(a) of the indicator should be near the pH of the solution at the equivalance point. Given that the K_(a) (methy 1 orange) = 4.0 xx 10^(-4) , a solution at pH = 2 containing the indicator would be

Knowledge Check

  • An indicator has pK_(In)=5.3 . In a certain titration, this indicator is found to be 80% ionized in its acid form. Thus, pH of the solution is

    A
    `4.7`
    B
    `5.3`
    C
    `5.9`
    D
    `6.2`

  • An indicator is a weak acid and pH range of its colour is 3 to 5 . If the neutral point of the indicator lies in the centre of the [H^(+)] corresponding to given pH range, then pH at the equivalence point is

    A
    `7.0`
    B
    `4.0`
    C
    `3.3`
    D
    `5.0`

  • A 0.015 M solution of a weak acid has a pH of 3.52 . What is the value of the K_a for this acid?

    A
    `2.0xx10^(-2)`
    B
    `6.2xx10^(-6)`
    C
    `9.1xx10^(-8)`
    D
    `1.4xx10^(-9)`