Question

An industrial chemist converts Zn(H₂O)₄²⁺ to the more stable Zn(H₃O)₄²⁺ by mixing 50.0 L of 0.0020 M Zn(H₂O)₄²⁺ and 25.0 L of 0.15 M NH₃. What is the final [Zn(H₂O)₄²⁺] at equilibrium? Kf of Zn(H₃O)₄ is 7.8x10⁸

Answer 1

To find the equilibrium concentration of Zn(H2O)4(2+), the initial moles of reactants are calculated, an ICE table is constructed, and the formation constant Kf is applied. The calculation assumes the reaction goes nearly to completion due to the high Kf value.

Step-by-step explanation:

The student wants to determine the equilibrium concentration of Zn(H2O)42+ after it has been converted to a more stable complex ion by reaction with ammonia. Given the total volume and initial molarity, we must first calculate the number of moles of Zn(H2O)42+ and NH3. Then we use the formation constant (Kf) to find the equilibrium concentrations of the species involved.

Calculation Steps

1. Calculate the initial moles of Zn(H2O)42+ using volume and concentration.
2. Calculate the initial moles of NH3 similarly.
3. Set up an ICE (Initial, Change, Equilibrium) table to determine the changes in concentrations as the reaction reaches equilibrium.
4. Apply the Kf value for Zn(H3O)42+ to find the equilibrium concentrations.
5. From the equilibrium concentration, ascertain the final concentration of Zn(H2O)42+ using the stoichiometry of the reaction.

Note that due to the high Kf value, it's assumed that the reaction goes to completion. Detailed calculations will reveal how much of the original Zn(H2O)42+ remains unreacted at equilibrium and therefore, its final concentration.