91Ó°ÊÓ

A metal forms the fluoride \(\mathrm{MF}_{3}\) .. Electrolysis of the molten fluoride by a current of 3.86 A for 16.2 minutes deposits 1.25 g of the metal. Calculate the molar mass of the metal.

A sample of impure tin of mass 0.535 g is dissolved in strong acid to give a solution of \(S n^{2+} .\) The solution is then titrated with a 0.0448 \(\mathrm{M}\) solution of \(\mathrm{NO}_{3}^{-},\) which is reduced to \(\mathrm{NO}(g) .\) The equivalence point is reached upon the addition of 0.0344 L of the \(\mathrm{NO}_{3}^{-}\) solution. Find the percent by mass of tin in the original sample, assuming that it contains no other reducing agents.

A 0.0251 \(\mathrm{L}\) sample of a solution of \(\mathrm{Cu}^{+}\) requires 0.0322 \(\mathrm{L}\) of 0.129 \(\mathrm{M} \mathrm{KM} \mathrm{nO}_{4}\) solution to reach the equivalence point. The products of the reaction are \(\mathrm{Cu}^{2+}\) and \(\mathrm{Mn}^{2+} .\) What is the concentration ofthe \(\mathrm{Cu}^{2+}\) solution?

Which oxidizing agent oxidizes \(\mathrm{Br}^{-}\) but not \(\mathrm{Cl}^{-}?\) a. \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}(\mathrm{inacid}) \quad\) b. \(\mathrm{KMnO}_{4}(\mathrm{in}\) acid \()\) \(\mathbf{c} \cdot \mathrm{HNO}_{3}\)

A redox reaction employed in an electrochemical cell has a negative \(\Delta G_{\mathrm{rxn}}^{\circ}\) Which statement is true? a. \(E_{\mathrm{cell}}^{\circ}\) is positive; \(K<1\) b. \(E_{\text { cell }}^{\circ}\) is positive; \(K>1\) c. \(E_{\text { cell }}^{\circ}\) is negative; \(K>1\) d. \(E_{\text { cell }}^{\circ}\) is negative; \(K<1\) A redox reaction has an equilibrium constant of \(K=0.055 .\) What is true of \(\Delta G_{\mathrm{ran}}^{\circ}\) and \(E_{\text { cell }}^{\circ}\) for this reaction?