Salts：練習題

All salts of which group or ion are consistently soluble in water?

A student wishes to prepare a sample of potassium sulfate. Which pair of reagents would be most appropriate for a titration method?

Which of the following procedures would be most successful for preparing a pure, dry sample of lead(II) chloride, \( PbCl_{2} \), starting from lead(II) carbonate, \( PbCO_{3} \)?

Which reagent could be used to differentiate between a solution of sodium chloride and a solution of sodium iodide?

A salt is prepared by reacting an excess of an insoluble metal oxide with a dilute acid. The mixture is then filtered. What is the correct sequence of steps to obtain pure crystals of the salt from the filtrate?

Identify which of the following chloride salts is insoluble in cold water: \( NaCl \), \( MgCl_{2} \), \( PbCl_{2} \), or \( CaCl_{2} \).

A student needs to prepare a pure sample of the insoluble salt, barium sulfate, \( BaSO_{4} \).

Suggest the names of two suitable aqueous starting reagents and the name of the technique used to separate the salt from the reaction mixture.

A student is asked to prepare a pure, dry sample of the insoluble salt lead(II) sulfate, \( PbSO_{4} \), starting from lead(II) oxide powder.

(a) Explain why lead(II) oxide cannot be converted directly into lead(II) sulfate by adding dilute sulfuric acid.
(b) A two-step method is required. Name the reagent that should be added to lead(II) oxide in the first step to produce a soluble intermediate, and name a suitable reagent for the second step to precipitate the lead(II) sulfate.
(c) In an experiment, \( 11.15\text{ g} \) of lead(II) oxide is completely reacted to form a solution of the soluble intermediate. Calculate the volume of \( 0.50\text{ mol/dm}^3 \) sodium sulfate solution required to react exactly with this solution. [\( A_r \): \( Pb = 207, O = 16 \)]
(d) Briefly describe how the student can obtain a pure, dry sample of lead(II) sulfate from the mixture produced in step (b) after the reaction is complete.

A student aims to prepare a pure sample of the salt zinc sulfate using two different methods.

(a) Identify a suitable metal and a dilute acid that can react together to produce zinc sulfate. Write a balanced chemical equation for this reaction, including state symbols.
(b) Describe the steps the student should take to obtain pure, dry crystals of zinc sulfate from the reaction mixture in part (a), starting from the point where the reaction is complete.
(c) Explain why the method of reacting an excess of zinc metal with dilute sulfuric acid is preferred over reacting exactly stoichiometric amounts of the reactants.

The preparation of salts depends on their solubility in water. Consider the following two salts: barium sulfate and sodium nitrate.

(a) State whether each of these salts is soluble or insoluble in water.
(b) Suggest a method to prepare a pure, dry sample of barium sulfate. In your answer, name the two starting aqueous solutions required and describe the experimental procedure involved.
(c) To prepare sodium nitrate, the method of titration is typically used. Explain why the method used for barium sulfate in part (b) cannot be used to prepare sodium nitrate.
(d) Write the ionic equation, with state symbols, for the formation of barium sulfate from your chosen reactants in part (b).