Question

The ionisation constant of dimethylamine is 5·4 × 10^–4. Calculate its degree of ionisation in its 0-02M solution. What percentage of dimethylamine is ionised if the solution is also 0·1M in NaOH?

Solution

We know,
$straight alpha space equals square root of straight K subscript straight b over straight C end root space equals space square root of left parenthesis 5.4 space cross times space 10 to the power of negative 4 end exponent divided by left parenthesis 2 space cross times space 10 to the power of negative 2 end exponent right parenthesis end root space space equals space 0.164$
Suppose x is the amount of dimethylamine dissociated in the presence of 0.1 M NaOH.
(CH₃)₂NH + H₂O $rightwards harpoon over leftwards harpoon$ (CH₃)₂NH⁺OH^- + OH^-Initial conc
0.02 M 0 0
After
dissociation
0.02 - x x 0.1 + x
= 0.02 = 0.1
$straight K subscript straight b space equals space fraction numerator open square brackets left parenthesis CH subscript 3 right parenthesis subscript 2 NH to the power of plus OH to the power of minus close square brackets space open square brackets OH to the power of minus close square brackets over denominator open square brackets left parenthesis CH subscript 3 right parenthesis subscript 2 NH close square brackets end fraction space equals space fraction numerator straight x left parenthesis 0.1 right parenthesis over denominator 0.02 end fraction space fraction numerator straight x over denominator 0.02 end fraction space equals space fraction numerator straight K subscript straight b over denominator 0.1 end fraction space equals space fraction numerator 5.4 space cross times space 10 to the power of negative 4 end exponent over denominator 0.1 end fraction space equals space 5.4 space cross times space 10 to the power of negative 3 end exponent straight i. straight e. space straight alpha space equals space fraction numerator straight x over denominator 0.02 end fraction space equals space 5.4 space cross times space 10 to the power of negative 3 end exponent therefore space percent sign space age space of space ionisation space of space dimethylamine space equals space 0.54$

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Equilibrium

The ionisation constant of dimethylamine is 5·4 × 10^–4. Calculate its degree of ionisation in its 0-02M solution. What percentage of dimethylamine is ionised if the solution is also 0·1M in NaOH?

Some More Questions From Equilibrium Chapter

What kind of molecules in a liquid can evaporate?

Name the factors on which vapour pressure of any liquid depends.

Which measurable property becomes constant in water vapour equilibrium?

Give an example from daily life in which there is gas solution equilibrium?

A crystal of common salt of a given mass is kept in its aqueous solution. After 24 hours, its mass remains the same. Is the crystal in equilibrium with the solution?

What is the role of forward and backward reactions at equilibrium of a reversible reaction?

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Equilibrium

The ionisation constant of dimethylamine is 5·4 × 10–4. Calculate its degree of ionisation in its 0-02M solution. What percentage of dimethylamine is ionised if the solution is also 0·1M in NaOH?

Some More Questions From Equilibrium Chapter

What kind of molecules in a liquid can evaporate?

Name the factors on which vapour pressure of any liquid depends.

Which measurable property becomes constant in water vapour equilibrium?

Give an example from daily life in which there is gas solution equilibrium?

A crystal of common salt of a given mass is kept in its aqueous solution. After 24 hours, its mass remains the same. Is the crystal in equilibrium with the solution?

What is the role of forward and backward reactions at equilibrium of a reversible reaction?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

The ionisation constant of dimethylamine is 5·4 × 10^–4. Calculate its degree of ionisation in its 0-02M solution. What percentage of dimethylamine is ionised if the solution is also 0·1M in NaOH?