An aqueous precipitation reaction is described by the balanced net-ionic equation…
CHEMISTRY · Multi-part · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
An aqueous precipitation reaction is described by the balanced net-ionic equation
Ag⁺(aq) + Cl⁻(aq) → AgCl(s)
A particulate diagram of a 100-mL reaction mixture shows the following.
• 6 solvated Ag⁺ ions (depicted as gray spheres with a “+” sign).
• 4 solvated Cl⁻ ions (depicted as green spheres with a “–” sign).
• 4 solid AgCl units clustered together (each unit represented as a touching gray–green pair).
Assume the diagram intends to represent the system after the reaction has proceeded as far as possible under the given stoichiometry.
Apply the law of conservation of both mass and charge to assess and correct the representation.
(a) Calculate the number of Ag⁺ ions and Cl⁻ ions that must have combined to produce the 4 units of solid AgCl shown.
(b) Using your result from part (a), determine how many excess (unreacted) ions of each type should be present in the solution after precipitation is complete.
(c) Compare the required numbers from parts (a) and (b) with the actual counts given in the diagram. Identify every inconsistency with respect to (i) stoichiometric ratios and (ii) overall charge balance.
(d) Specify the exact changes (adding or removing particular ions or solid units) needed to correct the diagram so it accurately represents the reaction mixture at completion.