a. The principal equilibrium in a solution of NaHCO 3 is HCO 3 − ( a q ) + HCO 3 − ( a q ) ⇌ H 2 CO 3 ( a q ) + CO 3 2 − ( a q ) Calculate the value of the equilibrium constant for this reaction. b. At equilibrium, what is the relationship between [H 2 CO 3 ] and [CO 3 2− ]? c. Using the equilibrium H 2 CO 3 ( a q ) ⇌ 2 H + ( a q ) + CO 3 2 − ( a q ) derive an expression for the pH of the solution in terms of K a 1 and K a 2 using the result from part b. d. What is the pH of a solution of NaHCO 3 ?

Interpretation: The value of equilibrium constant, relationship between [H2CO3] and [CO32−] at equilibrium,. expression for pH in terms of Ka1 and Ka2, pH of NaHCO3.

Concept introduction: The equilibrium constant is defined as the numeric number that describes the relationship between amount of product and amount of reactant at equilibrium. The pH is the scale that measures the power of hydrogen ion concentration of a species.

To determine: The value of equilibrium constant.

Explanation

The given reaction is,

HCO3−+HCO3−⇌H2CO3+CO32−

The equilibrium constant expression is,

Keq=[concentration of product][concentration of reactants]

The equilibrium constant expression for the given reaction is,

Keq=[H2CO3][CO32−][HCO3−][HCO3−]

Multiply numerator and denominator by [H+].

Keq=[H2CO3][CO32−][HCO3−][HCO3−] [H+][H+] (1)

Rearrange the above equation (1)

Keq=[H+][CO32−][H2CO3][HCO3−][H+

Interpretation: The value of equilibrium constant, relationship between [H2CO3] and [CO32−] at equilibrium,. expression for pH in terms of Ka1 and Ka2, pH of NaHCO3.

Concept introduction: The equilibrium constant is defined as the numeric number that describes the relationship between amount of product and amount of reactant at equilibrium. The pH is the scale that measures the power of hydrogen ion concentration of a species.

To determine: The relationship between [H2CO3] and [CO32−] at equilibrium.

Interpretation: The value of equilibrium constant, relationship between [H2CO3] and [CO32−] at equilibrium,. expression for pH in terms of Ka1 and Ka2, pH of NaHCO3.

Concept introduction: The equilibrium constant is defined as the numeric number that describes the relationship between amount of product and amount of reactant at equilibrium. The pH is the scale that measures the power of hydrogen ion concentration of a species.

To determine: The expression for pH in terms of Ka1 and Ka2.

Interpretation: The value of equilibrium constant, relationship between [H2CO3] and [CO32−] at equilibrium,. expression for pH in terms of Ka1 and Ka2, pH of NaHCO3.

Concept introduction: The equilibrium constant is defined as the numeric number that describes the relationship between amount of product and amount of reactant at equilibrium. The pH is the scale that measures the power of hydrogen ion concentration of a species.

To determine: The pH of NaHCO3.