Chapter 18

Describe two principal solvent extraction systems for metal ions. Give examples of each.

What is the basis of accelerated solvent extraction?

How does solid-phase extraction differ from solvent extraction?

In deriving Equation \(18.8,\) we neglected the fact that benzoic acid partially forms a dimer in the organic phase \(\left(2 \mathrm{HBz} \rightleftharpoons(\mathrm{HBz})_{2} ; K_{p}=\left[(\mathrm{HBz})_{2}\right] /[\mathrm{HBz}]^{2}\right.\), where \(K_{n}\) is the dimerization constant). Derive an expression for the distribution ratio taking this into account.

The distribution ratio between \(3 M \mathrm{HCl}\) and tri-n-butylphosphate for \(\mathrm{PdCl}_{2}\) is 2.3. What percent \(\mathrm{PdCl}_{2}\) will be extracted from \(25.0 \mathrm{~mL}\) of a \(7.0 \times 10^{-4} \mathrm{M}\) solution into \(10.0 \mathrm{~mL}\) tri- \(n\) -butylphosphate?

Ninety percent of a metal chelate is extracted when equal volumes of aqueous and organic phases are used. What will be the percent extracted if the volume of the organic phase is doubled?

For a solute with a distribution ratio of \(25.0,\) show by calculation which is more effective, extraction of \(10 \mathrm{~mL}\) of an aqueous solution with \(10 \mathrm{~mL}\) organic solvent or extraction with two separate 5.0 -mL portions of organic solvent.

Arsenic(III) is \(70 \%\) extracted from \(7 M \mathrm{HCl}\) into an equal volume of toluene. What percentage will remain unextracted after three individual extractions with toluene?