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Equilibrium

Question
CBSEENCH11006597
Wired Faculty App

Determine the pH of a solution obtained by mixing equal volumes of 0·015N NH4OH and 0·15N NH4NO3 solutions. (Kb for NH4OH is 1·8 × 10–5).

Solution
For a basic buffer, Henderson equation is
pOH space equals space pK subscript straight b space plus space log space fraction numerator open square brackets Salt close square brackets over denominator open square brackets Base close square brackets end fraction space space space space... left parenthesis 1 right parenthesis
Here,  on mixing equal volumes of two solutions,
     open square brackets NH subscript 4 OH close square brackets space equals space space fraction numerator 0.015 over denominator 2 end fraction space equals 0.0075 space straight N open square brackets NH subscript 4 NO subscript 3 close square brackets space equals space fraction numerator 0.015 over denominator 2 end fraction equals space 0.075 space straight N space space space space space space pK subscript straight b space equals space log space straight K subscript straight b space space space space space space space space space space space space space equals log space left parenthesis 1.8 space cross times space 10 to the power of negative 5 end exponent right parenthesis space space space space space space space space space space space
Substituting the values in equation (1), we get,
 
    pOH space equals space 4.7447 space plus space log space fraction numerator 0.075 over denominator 0.0075 end fraction space space space space space space space equals 4.7447 space plus space log space 10 space space space space space space space equals 4.7447 space plus 1 space equals space 5.7447 But space pH space plus space pOH space equals space 14 therefore space space space space pH space equals space 14 space minus space pOH space space space space space space space space space space space space equals space 14 minus 5.7447 space equals space 8.2553

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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