Using dissociation constants from Appendix D, determine the value for the equilibrium constant for each of the following reactions. (i) HCO3-1aq2 + OH-1aq2 ΔCO32-1aq2 + H2O1l2 (ii) NH4+1aq2 + CO32-1aq2 ΔNH31aq2 + HCO3-1aq2

Verified step by step guidance

1. Identify the dissociation reactions and their constants (Ka or Kb) for each species involved in the given reactions. For reaction (i), look up the Ka for HCO3- dissociating to CO3^2- and H+, and the Kb for OH- reacting to form H2O and O2-. For reaction (ii), find the Kb for NH4+ dissociating to NH3 and H+, and the Ka for CO3^2- dissociating to HCO3- and OH-.
2. Write the equilibrium expressions for each dissociation reaction using the formula Ka = [Products]/[Reactants] for acid dissociation and Kb = [Products]/[Reactants] for base dissociation. Ensure to exclude water (H2O) in the expression as its concentration remains relatively constant.
3. Combine the expressions from step 2 to form the overall equilibrium constant (K) for the given reactions. For reaction (i), multiply the Ka of HCO3- by the reciprocal of the Kb of OH- (since OH- is a base and its reaction is the reverse of dissociation). For reaction (ii), multiply the Kb of NH4+ by the reciprocal of the Ka of CO3^2-.
4. Simplify the expressions obtained in step 3 to get the final form of the equilibrium constant for each reaction. This involves canceling out any common species and simplifying the mathematical expression.
5. Use the values of Ka and Kb from Appendix D to substitute into the simplified expressions from step 4 to calculate the numerical values of the equilibrium constants for reactions (i) and (ii).

Key Concepts

Dissociation Constants

Dissociation constants (K) are equilibrium constants that describe the extent to which a compound dissociates into its ions in solution. For acids and bases, these constants help quantify the strength of the acid or base. The larger the dissociation constant, the stronger the acid or base, indicating a greater tendency to donate or accept protons.

Equilibrium Constant (K_eq)

The equilibrium constant (K_eq) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction. It is calculated using the formula K_eq = [products]/[reactants], where the concentrations are raised to the power of their coefficients in the balanced equation. Understanding K_eq is essential for predicting the direction of a reaction and its extent.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. This principle is crucial in understanding how changes in concentration, temperature, or pressure affect the position of equilibrium in chemical reactions, including those involving acids and bases.