This document discusses the preparation and classification of salts. Salts are formed through the replacement of hydrogen ions in acids by metal ions or ammonium ions. There are two main methods for preparing salts - neutralization and precipitation. Neutralization involves reacting an acid with a metal, alkali, oxide or carbonate to form a soluble salt. Precipitation involves mixing two aqueous solutions of soluble salts to form an insoluble salt precipitate. The document provides examples of preparing various salts such as potassium chloride and lead chloride. It also discusses classifying salts as soluble or insoluble and purifying soluble salts through recrystallization.

1. CHAPTER 8: SALTS

2. WHO IS SALT ?

3. WHAT IS SALT ? WHO IS SALT ? Ionic compound – formed when the hydrogen ion, H+ from an acid is replaced by a metal ion or an ammonium ion, NH4+ REFER TEXT BOOK : PAGE 138

4. EXAMPLE : replace Na+ Na+ Cl- Metal ions Sodium chloride H Cl replace NH4+ NH4+ Cl- Ammonium ion Ammonium chloride

5. SALTS CONSIST ANION PART COMES FROM THE ACID WHILE CATION PART COMES FROM BASES Common anions (parent acids) Common cations HCl Na+ Ca2+ Mg2+ Fe2+ HNO3 K+ Cu2+ Al3+ Zn2+ H2CO3 NH4+ Fe3+ Pb2+ H2SO4

6. METAL ION DISPLACE H+ ION IN ACIDS

8. All nitrate salts ; soluble salts ALL NO3- SOLUBLE SALT

9. All Na+, K+, NH4+ salts ; soluble salts ALL Na+, K+, NH4+ SOLUBLE SALT

10. All carbonate salts ; insoluble salts EXCEPT CO32- ALL INSOLUBLE SALT EXCEPT Na+, K+, NH4+

11. All SO42-, Cl- salts ; soluble salts EXCEPT EXCEPT EXCEPT ALL ALL Pb2+ Ag+ Hg2+ Pb2+ Ca 2+ Ba2+ Cl- SO42- SOLUBLE SALT SOLUBLE SALT

13. INSOLUBLE SALT SOLUBLE SALT PbSO4 ALL SO42- CaSO4 ALL BaSO4 ALL NO3- CO32- ALL Cl- AgCl ALL PbCl2 Na+, K+, NH4+ CLASSIFICATION OF SALTS

14. PREPARATION OF SALTS SOLUBLE SALTS INSOLUBLE SALTS NEUTRALISATION OTHER METHOD PRECIPITATION ACID + METAL ACID + ALKALI SOLUBLE SALT + SOLUBLE SALT ACID + METAL OXIDE [SPA] Sodium ,Na+ salts Potassium, K+ salts Ammonium, NH4+ salts INSOLUBLE SALT & SOLUBLE SALT ACID + METAL CARBONATE OTHER SOLUBLE SALTS

15. PREPARATION OF SOLUBLE SALTS [ SODIUM SALTS / POTASSIUM SALTS / AMMONIUM SALTS ] NEUTRALISATION REACTION EXAMPLE PREPARATION OF POTASSIUM CHLORIDE K OH H Cl Cl K H2O ALKALI ACID SALTS TITRATION METHOD – FIND OUT THE EXACTLY VOLUME OF ACID REQUIRED TO NEUTRALISE ALKALI. END POINT – POINT WHEN INDICATOR CHANGES COLOUR DURING TITRATION NOTE : CONCENTRATION AND VOLUME OF ALKALI ARE KNOWN.

16. LET DO THIS: PREPARATION OF POTASSIUM CHLORIDE APPARATUS : Pipette 25mL, Burette 50mL, Conical Flask 250 mL MATERIALS : Potassium hydroxide 1.0 M, Hydrochloric acid 1.0 M, Phenolphthalein Use a pipette to transfer 25.0 cm3 of potassium hydroxide solution to a conical flask. Add 2 to 3 drops of phenolphthalein Fill a burette with hydrochloric acid and record the initial burette reading. Slowly adding the acid into the conical flask and swirls- until the indicator turns from pink to colourless. Record the volume of acid used. (V cm3) Record the final burette reading in 2d.p Colourless KOH turn to pink. Record the burette reading in 2d.p

17. PREPARATION OF POTASSIUM CHLORIDE START OVER AGAIN BUT WITHOUT INDICATOR : To get the pure and neutral salt solution Pipette 25.0 cm3 of the same potassium hydroxide solution into a conical flask. Do not add any indicator. From the burette, add exactly V cm3 of hydrochloric acid to the alkali and swirls and shake well. RECRYSTALLISATION PROCESS [PURIFIED SOLUBLE SALTS] HEATING/EVAPORATE COOLING FILTRATION DRY Solution salt contains impurities continuous with recrystallisation process CRYSTAL SALT

18. PREPARATION OF SOLUBLE SALTS [ OTHER SALTS EXCEPT Na+, K+, NH4+] OTHER METHOD : DISSOLVE METAL IN ACID Pour 50 cm3of sulphuric acid into a beaker. Warm the acid Use a spatula to add copper(II) oxide powder bit by bit into the acid. Stir the mixture well. Continue adding copper(II) oxide until some of it no longer dissolves(excess unreacted metal Metal/ metal oxide/ metal carbonate Excess unreactedmetal (residue) Glass rod Acid Evaporating basin with salt solution (filtrate) Solution salt contains impurities continuous with recrystallisation process See the change of metal solid colour and dissolve

19. RECRYSTALLISATION PROCESS [PURIFIED SOLUBLE SALTS] HEATING/EVAPORATE COOLING Salt solution Evaporating basin Crystal salt

21. Flat faces, straight edges and sharp angles.

22. Same angle between adjacent faces.Glass rod Rinse with distilled water Filter Paper Salt Cystals The crystals are filtered and rinsed with a little cold distilled water.

23. DISSOLVE SOLUTE IN ACID PREPARATION OF SOLUBLE SALTS NEUTRALISATION REACTION 1ST TITRATION WITH INDICATOR FIND VOLUME OF ACID HEATING DISSOLVE METAL IN ACID TRANSFER TO EVAPORATING BASIN EXCESS METAL NOT DISSOLVE COMPLETE REACT 2ND TITRATION NO INDICATOR GET PURE SALT recrystalisation HEATING/EVAPORATE COOLING FILTRATION DRY CRYSTAL SALT

24. PREPARATION OF INSOLUBLE SALTS [ ALL CARBONATE SALTS except Na+/K+/NH4+ ] PbSO4 / CaSO4/ BaSO4/PbCl2/ AgCl] PRECIPITATION REACTION PREPARATION OF LEAD(II) CHLORIDE EXAMPLE Pb NO3 Na Cl Cl2 Pb NO3 Na SOLUBLE SALTS SOLUBLE SALTS INSOLUBLE SALTS DOUBLE DECOMPOSITION METHOD – TWO AQUOUES SOLUTIONS/SOLUBLE SALTS WERE MIX TOGETHER INTERCHANGE TO PRODUCE TWO NEW COMPOUND WHICH IS INSOLUBLESALT OR PRECIPITATE, AND AQUEOUS SOLUTION/SOLUBLE SALTS

25. PRECIPITATION REACTION two aquoues solutions/soluble salts were mix together [one of the solutions contains the cations of the insoluble salt] [one of the solutions contains the anions of the insoluble salt] the ions of the two aqueous solutions above interchange to produce two new compound which is insoluble salt or precipitate, and aqueous solution

26. PRECIPITATION REACTION Glass rod Glass rod Distilled water Mixture solutions Filter paper Precipitate (residue) Precipitate (residue) Filter funnel Retort stand Aqueous Solution (filterate) Rinse : remove other ions from precipitate Filtration : Remove solution from precipitate FILTRATION RINSE

27. PRECIPITATION REACTION FLOW CHART : PREPARATION OF INSOLUBLE SALTS Precipitate/Soluble salts Filter paper MIX - STIR TWO SOLUBLE SALTS Dry : Dried by pressing between two pieces of filter paper. FILTRATION REMOVE FILTRATE RINSE REMOVE OTHER IONS DRY PRESS BETWEEN FILTER PAPER

28. PREPARATION OF SALTS REMEMBER : METAL ION DISPLACE HYDROGEN ION IN ACID TO FORMED SALTS HCl [H+/Cl-] Hydrochloric acid METAL / AMMONIUM ION Na+ Ca2+ Zn2+ HNO3 [H+/NO3-] Nitric Acid K+ Al3+ Pb2+ H2SO4 [2H+/SO42-] Nitric Acid NH4+ Mg2+ Cu2+ H2CO3 [2H+/CO32-] Nitric Acid Fe2+ Fe3+

29. SUMMARIES OF REACTION

30. EXTRA INFO : REMEMBER Reactive metal is magnesium, aluminium, and zinc. Unreactivemetal is iron, lead, silver Metal that is less reactive from hydrogen such as copper, lead and silver did not react with dilute acid. Soluble salts of sodium, potassium and ammonium can be prepared by the reaction between an acid and alkali.

31. EXTRA INFO : REMEMBER Metal, metal oxide and metal carbonate is a solid that cannot dissolves in water, hence during reaction that solid must be added excessively to make sure all hydrogen ions in acid is completely reacted. Excess solid can be expelling through filtration. Unreactive metal such as lead (Pb), copper (Cu), and silver (Ag) cannot react with dilute acid. So to prepare salt contains lead ions (Pb2+), copper ions (Cu2+) or silver ions (Ag+), we must use either oxide powder or carbonate powder only. Impure soluble salt can be purified through crystallization process

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