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Equilibrium

Question
CBSEENCH11008102
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In aqueous solution the ionization constants for carbonic acid are
K1 = 4.2 x 10-7 and K2 = 4.8 x 10-11.
Select the correct statement for a saturated 0.034 M solution of the carbonic acid.

  • The concentration of CO32- is 0.034 M

  • The concentration of CO32- is greater than that of HCO3-

  • The concentration of H+ and HCO3- are approximately equal

  • The concentration of H+ is double that of CO32-

Solution

C.

The concentration of H+ and HCO3- are approximately equal

straight H subscript 2 CO subscript 3 space rightwards harpoon over leftwards harpoon with space on top space straight H to the power of plus space plus space HCO subscript 3 superscript minus space semicolon space straight K subscript 1 space equals space 4.2 space straight x space 10 to the power of negative 7 end exponent HCO subscript 3 superscript minus space rightwards harpoon over leftwards harpoon with space on top space straight H to the power of plus space plus space CO subscript 3 superscript 2 minus end superscript space semicolon space straight K subscript 2 space equals space 4.8 space straight x space 10 to the power of negative 11 end exponent straight K subscript 1 space greater than greater than space straight K subscript 2 therefore space left square bracket straight H to the power of plus right square bracket space equals space left square bracket HCO subscript 3 superscript minus right square bracket semicolon space straight K subscript 2 space equals space fraction numerator left square bracket straight H to the power of plus right square bracket left square bracket CO subscript 3 superscript 2 minus end superscript right square bracket over denominator left square bracket HCO subscript 3 superscript minus right square bracket end fraction So comma space left square bracket CO subscript 3 superscript 2 minus end superscript right square bracket space equals space straight K subscript 2 space equals space 4.8 space straight x space 10 to the power of negative 11 end exponent
Second dissociation constant is much smaller than the first one. Just a small fraction of total HCO3- formed will undergo the second stage of ionization. Hence in a saturated solution.

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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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