A solution containing potassium bromide is mixed with one containing lead acetate to form a solution that is 0.013 M in KBr and 0.0035 M in Pb(C2H3O2)2. Does a precipitate form in the mixed solution? If so, identify the precipitate.

Name: Chemistry: A Molecular Approach
Author: Tro
ISBN: 9780134874371

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Identify the possible reaction: When potassium bromide (KBr) and lead acetate (Pb(C_2H_3O_2)_2) are mixed, the possible reaction is the formation of lead bromide (PbBr_2) and potassium acetate (K(C_2H_3O_2)).

Write the balanced chemical equation: KBr + Pb(C_2H_3O_2)_2 \(\rightarrow\) PbBr_2 + 2K(C_2H_3O_2).

Determine the solubility product (K_sp) for PbBr_2: Look up the K_sp value for lead bromide (PbBr_2) in a solubility table.

Calculate the ion product (Q) for PbBr_2: Use the concentrations of Pb^{2+} and Br^- ions in the mixed solution to calculate Q. The concentration of Br^- is twice that of KBr, and the concentration of Pb^{2+} is the same as Pb(C_2H_3O_2)_2.

Compare Q with K_sp: If Q > K_sp, a precipitate of PbBr_2 will form. If Q < K_sp, no precipitate will form.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Solubility Product Constant (Ksp)

The solubility product constant (Ksp) is a numerical value that represents the equilibrium between a solid and its ions in a saturated solution. It is specific to a particular compound at a given temperature. For a precipitate to form, the product of the concentrations of the ions in solution must exceed the Ksp value of the potential precipitate.

Precipitation Reactions

Precipitation reactions occur when two soluble salts react in solution to form an insoluble compound, known as a precipitate. This process is driven by the formation of a solid that separates from the liquid phase, often indicated by a change in color or turbidity. Identifying the ions involved helps predict whether a precipitate will form.

Ion Concentration and Reaction Quotient (Q)

The reaction quotient (Q) is calculated using the current concentrations of the ions in solution. By comparing Q to the Ksp of a potential precipitate, one can determine if a precipitate will form. If Q exceeds Ksp, a precipitate will form; if Q is less than Ksp, no precipitate will form.

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