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Equilibrium

Question
CBSEENCH11006527
Wired Faculty App

Comment on the statement: An acidic solution contains OH– ions and even a basic solution contains H3O+ ions.
Or
How the values of Kw, [H3O+] and [OH–] are affected if acid or base is added to pure water at 298K?

Solution

We know, [H3O+][OH–] = Kw
For pure water, [H3O+] =[OH–]
= 1 × 10–7 mol L–1
On adding few drops of an acid (say HCl) to water, the concentration of H3O+ increases and thus concentration OH– decreases accordingly in order to maintain Kw constant.
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Hence acidic solution contains both hydronium and hydroxyl ions. But open vertical bar straight H subscript 3 straight O to the power of plus close vertical bar space greater than space open vertical bar OH to the power of minus close vertical bar But on adding. 
But on adding few drops of a base (say NaOH) to water, the concentration of OH–increases and thus the concentration of H3O+ decreases accordingly in order to maintain Kw constant.
NaOH space space rightwards harpoon over leftwards harpoon space space space space Na to the power of plus space plus space space OH to the power of minus open square brackets straight H subscript 3 straight O to the power of plus close square brackets space equals space fraction numerator straight K subscript straight w over denominator open square brackets OH to the power of minus close square brackets end fraction
Hence basic solution contains both hydronium and hydroxyl ions.
But [H3O+] < [OH–]
In general, in neutral solution,
[H3O+] = [OH–]
In acidic solution, [H3O+] > [OH–]
In basic solution, [H3O+] < [OH–]

 

Some More Questions From Equilibrium Chapter

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?

What is a forward reaction?

What condition favours a reversible reaction?

What is a backward reaction?

What type of equilibrium is attained in a reversibe chemical change?

What is meant by a system at dynamic equilibrium?

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