An ore sample with a total mass of contains by mass of lead(II) iodide, PbI

CHEMISTRY · Multi-part · AP · Chemistry · Equilibrium · Equilibrium

Problem

An ore sample with a total mass of

2.50\,\text{g}

contains

55.0\%

by mass of lead(II) iodide, PbI

_2

. The remainder of the sample consists of inert, insoluble material. The sample is finely ground and added to

150\,\text{mL}

of pure water at 25 °C. The dissolution of PbI

_2

is characterized by

K_{sp}=7.1\times10^{-9}

at this temperature. (a) Calculate the mass of PbI

_2

(in grams) present in the ore sample. (b) Determine the molar solubility of PbI

_2

(in mol L

^{-1}

) at 25 °C and hence the maximum mass of PbI

_2

that can dissolve in

150\,\text{mL}

of water. (c) Using your answers from parts (a) and (b), compute the mass of PbI

_2

(in grams) that remains undissolved after equilibrium is reached. (d) Calculate the equilibrium concentration of Pb

^{2+}

ions (in mol L

^{-1}

) in the saturated solution.