CHAPTER 8 : SALTS

Meaning and uses of Salts A salt is an ionic compound formed when the hydrogen ion, from an acid is replaced by a metal ion or an ammonium ion Example of salts : (i) sodium chloride (ii) potassium carbonate (iii) copper(II) sulphate

Examples of salts : AcidFormula of acid SaltFormulaCationAnion Hydrochloric acid HClSodium chloride NaClNa + Cl - Carbonic acid H 2 CO 3 Potassium carbonate K 2 CO 3 K+K+ SO 4 2- Sulphuric acid H 2 SO 4 Copper(II) sulphate CuSO 4 Cu 2+ SO 4 2-

Examples of salts : AcidFormula of acid SaltFormulaCationAnion Nitric acid HNO 3 Ammonium nitrate NH 4 NO 3 NH 4 + NO 3 - Ethanoi c acid CH 3 COOHSodium ethanoate CH 3 COONaNa + CH 3 COO - Nitric acid HNO 3 Magnesium nitrate Mg(NO 3 ) 2 Mg 2+ NO 3 -

Salts with their uses. SaltUses Barium sulphate BaSO 4 X-ray ‘meals’ in hospital Calsium sulphate CaSO 4 Plaster of Paris for broken bone Iron sulphate FeSO 4 Iron tablets for anaemia patient Ammonium nitrate NH 4 NO 3 Nitrogenous fertilizer

Salts with their uses. SaltUses Copper(II) sulphate CuSO 4 Fungicide Sodium chloride NaClA flavouring agent sodium hydrogen carbonate Baking powder Sodium nitrite NaNO 2 For preserving food/ food preservative

Salts with their uses. SaltUses Sodium hypochlorite NaOCl Bleaching agent Tin(II) fluoride SnF 2 Toothpaste Lead(II) chromate PbCrO 4 Paint for yellow line on road

Identify soluble and insoluble salt. Na + K + CO 3 2- NH 4 + Water NO 3 - Pb 2+ Ba 2+ SO 4 2- Ca 2+ Pb 2+ Ag + Cl - Hg +

All sodium, potassium and ammonium salts are soluble in water. All nitrate salts are soluble in water. All sulphate salts are soluble in water except lead(II) sulphate, barium sulphate and calcium sulphate. All chloride salts are soluble in water except lead(II) chloride, silver chloride and mercury chloride. All carbonate salts are insoluble in water except sodium carbonate, potassium carbonate and ammonium carbonate

State whether each of the following salt is soluble or insoluble in water Formula of salt Solubility ( / or x) Formula of salt Solubility ( / or x) PbCO 3 xNaCl/ CaSO 4 xAgNO 3 / K 2 CO 3 /FeCl 3 / Na 2 SO 4 /NH 4 NO 3 / CuSO 4 /PbCl 2 x

Chemical and ionic equations for reactions used in the preparation of soluble salts General equation for preparing soluble salts. a. metal + acid  salt + hydrogen b. metal oxide (or metal hydroxide) + acid  salt + water c. alkali + acid  salt + water d. metal carbonate + acid  salt + water + carbon dioxide

Complete the following chemical equation. Mg + H 2 SO 4  MgSO 4 + H 2 CuO + HCl  CuCl 2 + H 2 O Zn(OH) 2 + HNO 3  Zn(NO 3 ) 2 + H 2 O NaOH + HCl  NaCl + H 2 O MgCO 3 + H 2 SO 4  MgSO 4 + CO 2 + H 2 O

Preparation of soluble salt Method of Preparation ReactantsSalt Formed Other Product metal + acidMagnesium + hydrogen chloride Magnesium chloride Hydrogen metal oxide + acid Copper(II) oxide + sulphuric acid Copper(II) sulphate water Metal carbonate + acid Zinc carbonate + sulphuric acid Zinc sulphate Water + carbon dioxide

Preparation of soluble salt Method of Preparation ReactantsSalt Formed Other Product metal hydroxide + acid Potassium hydroxide + nitric acid Potassium nitrate water e) alkali + acid Sodium hydroxide + hydrochloric acid Sodium chloride water

The reactants which are needed to prepare the following soluble salts: Copper(II) sulphate : Copper(II) oxide / hydroxide / carbonate + sulphuric acid Zinc chloride: Zinc / (zinc oxide / hydroxide / carbonate) + hydrochloric acid Potassium nitrate: potassium hydroxide + nitric acid Ammonium sulphate: aqueous ammonia + sulphuric acid Magnesium nitrate: Magnesium / (magnesium oxide / hydroxide / carbonate) + nitric acid

Chemical equation can be simplified into an ionic equation. Example : Chemical equation : Zn(s) + H 2 SO 4 (aq)  ZnSO 4 (aq) + H 2 (g) Zn(s) + 2H + (aq) + SO 4 2- (aq)  Zn 2+ (aq) + SO 4 2- (aq) + H 2 (g) Ionic equation : Zn(s) + 2H + (aq)  Zn 2+ (aq) + H 2 (g)

Chemical equation can be simplified into an ionic equation. Chemical equation : Mg(s) + 2HCl(aq)  MgCl 2 (aq) + H 2 (g) Mg(s) + 2H + (aq) + 2Cl - (aq) Mg 2+ (aq) + 2Cl - (aq) + H 2 (g) Ionic equation : Mg(s) + 2H + (aq)  Mg 2+ (aq) + H 2 (g)

Chemical equation can be simplified into an ionic equation. Chemical equation :MgO(s) + 2HCl(aq)  MgCl 2 (aq) + H 2 O (l) MgO(s) + 2H + (aq) + 2Cl - (aq) Mg 2+ (aq) + 2Cl - (aq) + H 2 O(l) Ionic equation : MgO(s) + 2H + (aq)  Mg 2+ (aq) + H 2 O (l)

Chemical equation can be simplified into an ionic equation. Chemical equation :NaOH (aq) + HNO 3 (aq)  NaNO 3 (aq) + H 2 O (l) Na + (aq) + OH - (aq) + H + (aq) + NO 3 - (aq) Na + (aq) + NO 3 - (aq) + H 2 O(l) Ionic equation :OH - (aq) + H + (aq)  H 2 O (l)

Chemical equation can be simplified into an ionic equation. Chemical equation :CuCO 3 (s) + H 2 SO 4 (aq)  CuSO 4 (aq) + CO 2 (g) + H 2 O (l) CuCO 3 (s) + 2H + (aq) + SO 4 2- (aq) Cu 2+ (aq) + SO 4 2- (aq) + CO 2 (g) + H 2 O(l) Ionic equation : CuCO 3 (s) + 2H + (aq)  Cu 2+ (aq) + CO 2 (g) + H 2 O (l)

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Soluble saltSodium Chloride, NaCl Name two chemical substances to prepare the salt sodium hydroxide hydrochloric acid Chemical equationNaOH + HCl  NaCl + H 2 O

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 1. A pipette is used to transfer 25.0of sodium hydroxide solution to a conical flask. 2 to 3 drops of phenolphthalein is added. 2. A burette is filled with hydrochloric acid and record the initial burette reading. 3. Titration is carried out carefully by slowly adding the acid into the conical flask and the flask is shaken well. 4. The acid is added continuously until the indicator turns from pink to colourless. The final burette reading is recorded.

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 5. The volume of acid used to neutralize 25.0of the alkali is determined. (let the volume be V) of the same sodium hydroxide solution is pipetted into a conical flask. No indicator is addeded. 7. From the burette, exactly Vof hydrochloric acid is added to the alkali and is shaken well.

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 8. The contents of the conical flask is poured into an evaporating dish. 9. The solution is heated gently to evaporate most of the water to produce a saturated solution.

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 10. The hot saturated salt solution is cooled for crystallization to occur.

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 11.The sodium chloride crystals is filtered, and the salt is rinsed with a little distilled water.

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 12. The crystals are dried by pressing them between filter papers

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description Describe the physical characteristics of the crystals that you obtained Salt crystal characteristic 1. Flat surfaces, straight edges and sharp angles 2. Fixed geometrical shape 3. Fixed angles between two neighbouring surfaces 4. Crystals of some substance have same hapes but maybe in different sizes

Preparation of soluble salts (not sodium, potassium or ammonium salt) Soluble saltCopper(II) sulphate, CuSO 4 Name two chemical substances to prepare the salt copper(II) oxide and sulphuric acid Chemical equationCuO + H 2 SO 4  CuSO 4 + H 2 O

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 1. 50of sulphuric acid 1 mol dm-3 is poured into a beaker. The acid is warmed. 2. By using a spatula, copper(II) oxide powder is added bit by bit into the acid. The mixture is stirred well. 3. Copper(II) oxide is added continuously until some of it no longer dissolves.

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 3. The unreacted copper(II) oxide is removed by filtration

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 4. The filtrate is filtered into an evaporating dish. The solution is heated gently to produce a saturated salt solution.

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 5. The saturated solution is cooled until crystals are formed

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 6. The copper(II) nitrate crystals are filtered, and are then rinsed with a little distilled water.

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description 7. The crystals are dried by pressing them between filter papers

The procedure for the preparation of soluble salts of sodium, potassium and ammonium Procedure: (Diagram)Description Describe the purification process of the crystals Purification process – Recrystallisation 1.The copper(II) sulphate crystals are placed in a beaker. 2.Enough distilled water is added to cover the crystals. The solution is gently heated and stirred with a glass rod. Water is added bit by bit until all the crystals are dissolved. 3. Impurities is removed by filtration and filtrate is poured into an evaporating dish. 4.The solution is heated gently to evaporate most of the water to produce a saturated solution. 5.The hot saturated salt solution is cooled for crystallization to occur. 6.The copper(II) nitrate crystals are filtered, and the salt is rinsed with a little distilled water. 7. The crystals are dried by pressing them between filter papers

Chemical and ionic equations for reactions used in the preparation of insoluble salts Insoluble salts can be prepared by precipitation method through double decomposition reaction. In this reaction, two different aqueous solution mutually exchange their ions, to form precipitate. Soluble salt solution + Soluble salt solution  Insoluble salt MX containing cation M + containing anion X - Chemical equation : AgNO 3 (aq) + NaCl (aq)  AgCl (s) + NaNO 3 (aq) Ionic equation : Ag + (aq) + Cl - (aq)  AgCl (s)

Preparation of insoluble salts Example 1: Barium sulphate, Solution 1: Barium chloride/nitrate Solution 2 :sodium/potassium sulphate Chemical equation :BaCl 2 + Na 2 SO 4  BaSO 4 + 2NaCl Ionic Equation : Ba 2+ + SO 4 2-  BaSO 4 Observation : White precipitate formed

Preparation of insoluble salts Example 2 :Copper(II) carbonate, CuCO 3, Solution 1:copper(II) nitrate/sulphate/chloride Solution 2 :Sodium/potassium carbonate Chemical equation :Cu(NO 3 ) 2 + Na 2 CO 3  CuCO 3 + 2NaNO 3 Ionic Equation : Cu 2+ + CO 3 2-  CuCO 3 Observation : Green precipitate formed

Preparation of insoluble salts Example 3 : Lead(II) chromate(VI),PbCrO 4, Solution 1:lead(II) nitrate Solution 2 :Sodium/potassium chromate(VI) Chemical equation :Pb(NO 3 ) 2 (aq) + K 2 CrO 4 (aq)  PbCrO 4 (s) + 2KNO 3 (aq) Ionic Equation : Pb 2+ + CrO 4 2-  PbCrO 4 Observation : Yellow precipitate formed

The preparation of insoluble salts Insoluble salt NameLead(II) iodide, PbI 2 Two chemical substances to prepare the salt (i) Lead(II) nitrate (ii) Sodium/potassium iodide

The preparation of insoluble salts Chemical equationPb(NO 3 ) 2 (aq) + 2KI (aq)  PbI 2 (s) + 2KNO 3 (aq) Ionic equationPb 2+ (aq) + 2I - (aq) PbI 2 (s)

The preparation of insoluble salts Procedure: (Diagram)Description cm 3 of 0.5 mol dm -3 lead(II) nitrate solution is poured into 50 cm 3 of 1.0 mol dm -3 potassium iodide in a beaker 2. The mixture is stirred with a glass rod

The preparation of insoluble salts Procedure: (Diagram)Description 3. A yellow precipitate of lead(II) iodide is formed immediately 4. The resulting mixture is then filtered

The preparation of insoluble salts Procedure: (Diagram)Description 5. The yellow precipitate is rinsed with distilled water to remove impurities

The preparation of insoluble salts Procedure: (Diagram)Description 6. The yellow solid, lead(II) iodide is then pressed between a few pieces of filter papers to be dried

Solve problems involving calculation of quantities of reactants or products in stoichiometric reactions Example 1 : A student prepares copper (II) nitrate by reacting copper (II) oxide with 100 cm3 1.5 mol dm-3 nitric acid. Calculate the mass of copper (II) oxide needed to react completely with the acid. [Relative atomic mass: Cu, 64 ; O, 16] Solution : Chemical equation : CuO + 2HNO3  Cu(NO3)2 + H2O Mole ratio : 1 mole 2 mole 1 mole 1 mole Number of moles of HNO3 = 1.5 x 100 = 0.15 mol 1000 Mole ratio of CuO : HNO3 = 1 : 2 Number of mole of CuO = 1 x 0.15 = mole 2 Mass of CuO = x ( ) = 6 g

Question : 1.Excess zinc powder is added to react completely with 50 cm 3 of 2.0 mol dm -3 hydrochloric acid. (a)Write an ionic equation for the reaction between zinc and hydrochloric acid. Zn + 2HCl  ZnCl 2 + H 2

Question : (b) Calculate the number of moles of hydrochloric acid used. No of mole of HCl mol = 2.0 x 50 = 0.1 mol 1000

Question : (c)Calculate the volume of hydrogen gas liberated at room conditions. [Molar volume: 24 dm 3 mol -1 ] Mole ratio HCl : H 2 = 2 : 1 No of mole of H 2 = 1/2 x 0.1 = 0.05 mol Volume of H 2 = 0.05 x 24 dm 3 = 1.2 dm 3

Question : 2Excess of magnesium carbonate powder, MgCO 3, is reacted with 100 cm 3 of a 1 mol dm -3 sulphuric acid H 2 SO 4, What is the mass of magnesium sulphate formed? [Relative atomic mass : Mg =24, O=16, S = 32 ]

Question : No of mole of H 2 SO 4 = 1.0 x 100 = 0.1 mol 1000 Mole ratio H 2 SO 4 : MgSO 4 = 1 : 1 No of mole of MgSO 4 = 0.1 mol Mass of MgSO 4 = 0.1 x ( x16) g = 12.0 g

Question : g of magnesium reacts with excess hydrochloric acid to produce hydrogen gas. Given that the relative molecular mass of H=1, Mg = 24, CI =35.5 and 1 mol of gas occupies 24 dm 3 at room temperature and pressure. Find the (a) mass of salt formed

Question : No of mole of Mg = 0.12 = No of mole of MgCl 2 = Mass of MgCl 2 = x ( x 35.5) = g

Question : (b) volume of gas produced No of mole of H 2 = mole Volume of H 2 = x 24 dm 3 = 0.12 dm 3 or 120 cm 3

Question : Example 2 : A sample of insoluble lead (II) sulphate is prepared by mixing 50 cm 3 of 1.0 mol dm -3 lead (II) nitrate solution and y of 1.5 mol dm -3 sulphuric acid. [Relative atomic mass: O, 16 ; S, 32 ; Pb, 207] (a)Calculate the volume, y, of the sulphuric acid needed to react completely with the lead (II) nitrate solution.

Question : Solution : Chemical equation : Pb(NO 3 ) 2 + H 2 SO 4  PbSO HNO 3 Mole ratio : 1 mole 1 mole 1 mole 2 mole Number of moles of Pb(NO 3 ) 2 = 1.0 x 50 = 0.05 mol 1000 Mole ratio of Pb(NO 3 ) 2 : H 2 SO 4 = 1 : 1  Number of mole of H 2 SO 4 reacted = 0.05 mol 1.5 x y = 0.05 mole 1000 y = 0.05 x 1000 = cm 3 1.5

Question : (b)Calculate the mass of lead (II) sulphate obtained. Solution : Number of mole of PbSO 4 = Number of moles of Pb(NO 3 ) 2 = 0.05 mol Mass of PbSO 4 = 0.05 x ( x 16) g = g

Question : 4. A sample of insoluble silver chloride is prepared by mixing 50 cm 3 of 1.0 mol dm -3 silver nitrate solution and z cm 3 of 0.5 mol dm -3 sodium chloride solution. [Relative atomic mass: Ag 108; Cl 35.5] (a)Write the chemical equation for the reaction between silver nitrate and sodium chloride. AgNO 3 + NaCl  AgCl + NaNO 3

Question : (b) Calculate the volume, z, of the sodium chloride needed to react completely with the silver nitrate solution Number of moles of AgNO 3 = 1.0 x 50 = 0.05 mol 1000 Mole ratio of AgNO 3 : NaCl = 1 : 1 Number of mole of NaCl = 0.5 x z = 0.05 mole 1000 Z = 0.05 x 1000 = 100 cm 3 0.5

Question : (c) Calculate the mass of silver chloride obtained. Number of mole of AgCl = Number of moles of AgNO 3 = 0.05 mol Mass of AgCl = 0.05 x ( ) g = g

Qualitative Analysis Qualtitative analysis of a salt is a chemical technique used to identify the ions that are present in a salt by analysing its physical and chemical properties.

Qualitative Analysis Colour (solid or solution) Substance or cation or anion Green powder,CuCO 3 Blue powderFe 2+ Cu 2+ Brown powderFe 3+ Black powderCuO, MnO 2

Qualitative Analysis Colour (solid or solution) Substance or cation or anion Yellow powder when hot and white when cold ZnO Brown powder when hot and yellow when cold PbO Blue solutionCu 2+ Pale green solutionFe 2+

Qualitative Analysis Colour (solid or solution) Substance or cation or anion Brown solutionFe3+ Solid : White Solution : colourless Cation : Ca 2+, Al 3+, Mg 2+, Pb 2+, Zn 2+ NH 4 + Solid : White Solution : colourless Anion : Cl -, CO 3 2-, SO 4 2-, NO 3 -

Qualitative Analysis SaltsSolubility in waterColour Lead(II) chloride, silver chloride, barium sulphate, lead(II) sulphate and calcium sulphate Insolublewhite Copper(II) carbonateInsolublegreen Iron(II) sulphatesolublegreen Iron(III) salts except carbonate SolubleBrown

Qualitative Analysis SaltsSolubility in water Colour Lead(II) sulphate Insolublewhite Zinc chloridesolublewhite Magnesium carbonate Insolublewhite

Qualitative Analysis SaltsSolubility in water Colour Ammonium carbonate solublewhite Lead(II) iodide / chromate(VI) InsolubleYellow

Confirmatory Tests for gases GasMethodDiagramObservation Carbon dioxide Bubble the gas produced into lime water Lime water turn milky/chalky

Confirmatory Tests for gases GasMethodDiagramObservation OxygenInsert a glowing splinter into the test tube Glowing splinter will be relighted

Confirmatory Tests for gases GasMethodDiagramObservation Nitrogen dioxide Observe the colour of gas produced. Bring a piece of moist blue litmus paper to the mouth of the test tube Brown gas, blue litmus paper change to red

Confirmatory Tests for gases GasMethodDiagramObservation ChlorineObserve the colour of the gas.Bring a piece of moist blue litmus paper to the mouth of the test tube Greenish yellow gas The colour of litmus paper change from blue  red  white

Confirmatory Tests for gases GasMethodDiagramObservation AmmoniaDip a glass rod into concentrated hydrochloric acid and bring a drop of acid to the mouth of the test tube/place moist red litmus paper at the mouth of the test tube White fume formed Red litmus paper change to blue.

Confirmatory Tests for gases GasMethodDiagramObservation HydrogenBring a lighted splinter to the mouth of the test tube. Mg + HCl release hydrogen gas ‘Pop' sound is heard

Confirmatory Tests for gases GasMethodDiagramObservation Hydrogen chloride Dip a glass rod into concentrate d ammonia solution and bring a drop of ammonia to the mouth of test tube White fume formed

Action of Heat On Carbonate Salts Carbonate salts (except Na + & K + ) decompose on heating giving off carbon dioxide gas and residue metal oxide

Action of Heat On Carbonate Salts Lime water turns chalky Metal oxidecolour Copper(II) oxide Black Zinc oxideHot : Yellow Cold : White Lead(II) oxide Hot : Brown Cold : Yellow Iron(III) oxide Brown

Action of Heat On Carbonate Salts Carbonate saltAction of heat Potassium carbonate K 2 CO 3, Sodium carbonate Na 2 CO 3 Not decompose by heat

Action of Heat On Carbonate Salts Carbonate saltAction of heat Metal Carbonate  metal oxide + carbon dioxide Calcium carbonate CaCO 3  CaO + CO 2 Observation : White solid formed. Gas liberated turn lime water chalky

Action of Heat On Carbonate Salts Carbonate saltAction of heat Magnesium carbonate MgCO 3  MgO + CO 2 Observation : White solid formed. Gas liberated turn lime water chalky Aluminium carbonate Al 2 (CO 3 ) 3  Al 2 O 3 + 3CO 2 Observation : White solid formed. Gas liberated turn lime water chalky

Action of Heat On Carbonate Salts Carbonate salt Action of heat Zinc carbonate ZnCO 3  ZnO + CO 2 Observation : The residue is yellow when hot and white when cold. Gas liberated turn lime water chalky Lead(II) carbonate PbCO 3  PbO + CO 2 Observation : The residue is brown when hot and yellow when cold. Gas liberated turn lime water chalky

Action of Heat On Carbonate Salts Carbonate saltAction of heat Copper(II) carbonate CuCO 3  CuO + CO 2 Observation : Black solid formed. Gas liberated turn lime water chalky

Action of Heat On Nitrate Salts Nitrates Salts - Decompose on heating liberate nitrogen dioxide gas and oxygen gas except NaNO 3 and KNO 3 which liberate oxygen gas only.

Action of Heat On Nitrate Salts Brown gas turn moist blue litmus to red (NO 2 ) Colourless gas relighted glowing splinter (O 2 ) Heat

Action of Heat On Nitrates Salts Nitrate salt Action of heat Metal Nitrate  metal nitrite + oxygen Potassium nitrate 2KNO 3  2 KNO 2 + O 2 Observation : white solid formed, gas released relighted glowing splinter Sodium nitrate 2NaNO 3  2 NaNO 2 + O 2 Observation : white solid formed, gas released relighted glowing splinter

Action of Heat On Nitrates Salts Nitrate salt Action of heat Metal Nitrate  metal oxide + nitrogen dioxide + oxygen Calcium nitrate 2Ca(NO 3 ) 2  2CaO + 4NO 2 + O 2 Observation : white solid formed, Brown gas which turns moist blue litmus red released. Another gas released relighted glowing splinter

Action of Heat On Nitrates Salts Nitrate saltAction of heat Magnesium nitrate 2Mg(NO 3 ) 2  2MgO + 4NO 2 + O 2 Observation : white solid formed, Brown gas which turns moist blue litmus red released. Another gas released relighted glowing splinter Zinc nitrate2Zn(NO 3 ) 2  2ZnO + 4NO 2 + O 2 Observation : The residue is yellow when hot and white when cold., Brown gas which turns moist blue litmus red released. Another gas released relighted glowing splinter

Action of Heat On Nitrates Salts Nitrate saltAction of heat Lead(II) nitrate 2Pb(NO 3 ) 2  2PbO + 4NO 2 + O 2 Observation : The residue is brown when hot and yellow when cold, Brown gas which turns moist blue litmus red released. Another gas released relighted glowing splinter Copper(II) nitrate 2Cu(NO 3 ) 2  2CuO + 4NO 2 + O 2 Observation : black solid formed, Brown gas which turns moist blue litmus red released. Another gas released relighted glowing splinter

Confirmatory Tests for Anions ANIONS CO 3 2- Cl - SO 4 2- NoClueSoNothing NO 3 - Cl - SO 4 2- Observation : White precipitate Observation : Brown ring

Confirmatory Tests for Anions TEST FOR ANIONS Anion test ClueSoNothing Cl - SO 4 2- NO 3 - Reagent No Reagent ClueSo NO 3 - Cl - SO 4 2- HatiH+H+ NO 3 - AgongAg + NO 3 - BalikBa 2+ Cl - HajiH+H+ Cl - HendakH+H+ SO 4 2- FetrahFe 2+ SO 4 2- HartaH+H+ SO 4 2-

Confirmatory Tests for Anions Anions CO 3 2- Cl - SO 4 2- NO HNO 3 + AgNO 3 + Dilute acid + HCl + BaCl 2 + dilute H 2 SO 4 + FeSO 4 + concentrated H 2 SO 4 Effervescence – CO 2 Lime water turns milky Ionic equation : 2H + + CO 3 2-  H 2 O + CO 2 White precipitate Ionic equation : Ag + + Cl -  AgCl White precipitate Ionic equation : Ba 2+ + SO 4 2-  BaSO 4 Brown ring

Confirmatory Tests for Anions Salt K1 Add BaCl 2 solution + HCl acid Inference : sulphate ion White precipitate formed

Confirmatory Tests for Anions Inference : chloride ion Add AgNO 3 solution + HNO 3 acid White precipitate formed Salt K2

Confirmatory Tests for Anions Inference : Nitrate ion Brown ring formed Add FeSO 4 solution + concentrated sulphuric acid Salt K3

Confirmatory Tests for Anions Effervescence, Gas bubbles, Gas turn lime water chalky Add sulphuric acid Inference : Carbonate ion Salt K4

CONFIRMATORY TEST FOR CATIONS (SODIUM HYDROXIDE AS REAGENT)

CATION Colourless / Unchanges Add/put in NaOH SOLUTIONWhite precipitate Precipitate Coloured Green Brown Blue Fe 2+ Fe 3+ Cu 2+ NH 4 + White Pb 2+ Zn 2+ Al 3+ Mg 2+ Ca 2+ PZAL MgC Undissolved / not soluble In excess NaOH solution Dissolved / soluble In excess NaOH solution Add / Put in EXCESS NaOH solution Pb 2+ Zn 2+ Al 3+ Ca 2+ Mg 2+ MgCPZAL

Dissolved / soluble in excess NaOH solution Undissolved / not soluble in excess NaOH solution Al 3+ Pb 2+ Zn 2+ Mg 2+ MgC Ca 2+ PZAL DissolvedUndissolved WhiteUnchanged Ca 2+ Mg 2+ Calcium sulphate [ undissolved salt ] White YellowUnchanged Add KI solution Add ion SO 4 2- solution Pb 2+ Zn 2+ Al 3+ Lead (II) sulphate [ undissolved salt ] Dissolved Unchanged Zn 2+ Al 3+ ZnMAP Add / put in NH 3 solution

CONFIRMATORY TEST FOR CATIONS (AMMONIA AS REAGENT)

CATION SOLUTION Colourless / UnchangedPrecipitate Add / put in NH 3 NH 4 + Ca 2+ ColouredWhite Green Brown Blue Fe 2+ Fe 3+ Cu 2+ Zn 2+ Mg 2+ Al 3+ Pb 2+ Dissolved / soluble in excess NH 3 solution Undissolved / not soluble in excess NH 3 Add / put in EXCESS NH 3 Zn 2+ Mg 2+ Al 3+ Pb 2+ ZnMAP DissolvedUndissolved

ZnMAP Mg 2+ Al 3+ Pb 2+ Dissolved Undissolved WhiteSoluble / colourless Add / put in SO 4 2- solution Lead (II) sulphate [ undissolved salt ] Pb 2+ Mg 2+ Al 3+ Colourless / unchangesWhite Mg 2+ Al 3+ Add / put in EXCESS NaOH

Reaction of Cations with alkali solution 1. Positive ions are identified by their reactions with a. sodium hydroxide NaOH solution b. Ammonia solution NH 3 2.In these reactions, the cations (positive metal ions) produce different coloured precipitate which may or may not be soluble in excess alkali.

Reaction of Cations with alkali solution See if Precipitate dissolves 5 drops of alkali (NaOH or NH 3 ) Solution of cations Look for precipitate

Reaction of Cations with alkali solution NaOH solution A littleIn excess Soluble ( , X ) Ca 2+ White precipitateX Zn 2+ White precipitate  Al 3+ White precipitate  Pb 2+ White precipitate  Mg 2+ White precipitateX Cu 2+ Blue precipitateX Fe 2+ Green precipitateX Fe 3+ Brown precipitateX

Reaction of Cations with alkali solution Ammonia solution, NH 3 A littleIn excess Soluble ( , X ) Ca 2+ No change  Zn 2+ White precipitate  Al 3+ White precipitateX Pb 2+ White precipitateX Mg 2+ White precipitateX Cu 2+ Blue precipitateX Fe 2+ Green precipitateX Fe 3+ Brown precipitateX

Reaction of Cations with alkali solution Salt K5 Add excess NaOH solution White precipitate formed Inference 2 : zinc, aluminium and lead(II) ions White precipitate Dissolves in excess NaOH solution alkali White precipitate does not dissolve in excess NaOH solution Inference 3: magnesium or calcium ions Inference 1 : ammonium ion Add 5 drops of NaOH solution

Reaction of Cations with alkali solution Salt K6 Add 5 drops of NH 3 solution Add NH 3 solution in excess Inference 5 : zinc ion White precipitate Dissolve in excess NH 3 solution White precipitate does not dissolve in excess NH 3 solution White precipitate formed Inference 6: magneisum, aluminium, lead(II) ions No White precipitate formed Inference 4 : calcium ion

Confirmatory Tests for Fe 2+, Fe 3+, Pb 2+ and NH 4 + CationName of ReagentObservation Pb 2+ Add a few drops of potassium iodide to the test tube containing 2 cm 3 of lead(II) nitrate solution (Pb 2+ ions) Add 2 cm 3 of distilled water and boil the mixture. Cool the contents using running water from the tap. Yellow precipitate is formed Which dissolve in the hot water and is reappear on cooling

Confirmatory Tests for Fe 2+, Fe 3+, Pb 2+ and NH 4 + CationName of ReagentObservation Fe 2+ Add a few drops of Potassium hexacyanoferrate(III) solution to the test tube containing 2 cm 3 of iron(II) sulphate solution (Fe 2+ ions) Dark blue precipitate is formed

Confirmatory Tests for Fe 2+, Fe 3+, Pb 2+ and NH 4 + CationName of ReagentObservation Fe 3+ Add a few drops of potassium thiocyanate solution to the test tube containing 2 cm 3 of iron(III) sulphate solution (Fe 3+ ions) Blood red solution is formed

Confirmatory Tests for Fe 2+, Fe 3+, Pb 2+ and NH 4 + CationName of ReagentObservation NH 4 + Add a few drops of Nessler reagent to the test tube containing 2 cm 3 of ammonium chloride solution ( NH 4 + ions) Brown precipitate is formed

Chemical test of Fe 2+ ions and Fe 3+ ions. Solution contains Fe 2+ ions or Fe 3+ ions. Light blue precipitate Dark blue precipitate Fe 2+ ions Fe 3+ ions K 4 Fe(CN) 6 Potassium hexacyanoferrate(II) Test I

Chemical test of Fe 2+ ions and Fe 3+ ions. (i) Pour 2 cm 3 of iron(II) sulphate solution and 2 cm 3 of iron(III) chloride solution into two test tubes respectively. Then add a few drops of potassium hexacyanoferrate(II) solution to two test tubes, Fe 2+ ions solution will form light blue precipitate whereas Fe 3+ ions solution will form dark blue precipitate

Chemical test of Fe 2+ ions and Fe 3+ ions. Test II Solution contains Fe 2+ ions or Fe 3+ ions. No change Blood red solution Fe 2+ ions Fe 3+ ions Potassium thiocyanate KSCN

Chemical test of Fe 2+ ions and Fe 3+ ions. (i) Pour 2 cm 3 of iron(II) sulphate solution and 2 cm 3 of iron(III) chloride solution into two test tube respectively. Then add a few drops of potassium thiocyanate solution to two test tubes, there is no change in Fe 2+ ions solution whereas Fe 3+ ions solution will form blood red solution.

Qualitative analysis to identify salts Identify the salt S1 The following tests were carried out to identify salt S1. Based on the observations given for each test, state its inference. Finally, identify salt S1

Qualitative analysis to identify salts TestObservationInference 1. Heat S1 strongly in a test tube. Identify any gas liberated.Brown gas and a gas relights a glowing splinter are liberated. Residue is brown when hot and yellow when cold Nitrogen dioxide gas, oxygen gas released. Residue is lead(II) oxide 2. Dissolve a spatulaful of S1 in distilled water. Divide into four portions and carry out the following tests: Residue dissolve in acid to produce colourless solution Fe 2+, Fe 3+ or Cu 2+ ions may not be present

Qualitative analysis to identify salts TestObservationInference (a) add solution until excess. White precipitate, dissolve in excess NaOH solution Zn 2+, Al 3+ or Pb 2+ ions may be present (b) add solution until excess White precipitate, insoluble in excess ammonia solution Pb 2+ or Al 3+ ion may be present

Qualitative analysis to identify salts TestObservationInference (c) add potassium iodide solution Yellow precipitate formed Confirm lead(II), Pb 2+ ions present (d) add dilute, H 2 SO 4 followed by FeSO 4 solution. Carefully add about 1cm 3 of concentrated H 2 SO 4 Brown ring formed Confirm nitrate, NO 3 - ions present

Conclusion for salt S1 : Lead(II) nitrate

Identify the salt S2 TestObservationInference 1. Pour about 2 cm 3 of S2 into a test tube. Add NaOH solution until excess White precipitate, dissolve in excess NaOH solution Zn 2+, Al 3+ or Pb 2+ ions may be present 2. Pour about 2 cm 3 of S2 into a test tube. Add NH 3 solution until excess White precipitate, dissolve in excess ammonia solution Zn 2+ ions may be present

Qualitative analysis to identify salts TestObservationInference 3. Pour about 2 cm 3 of S2 into a test tube. Add dilute, HNO 3 followed by silver nitrate, AgNO 3 solution No changeCl - ions not present 4. Pour about 2 cm 3 of S2 into a test tube. Add dilute HCl solution, then add BaCl 2 solution White precipitate SO 4 2- ions may be present

Conclusion for salt S2 : Zinc sulphate

SODIUM CARBONATE AND SODIUM NITRATE

Test 1 Add dilute (any acid) Test 2 add dilute H 2 SO 4 followed by FeSO 4 solution. Carefully add 1of concentrated H 2 SO 4 Test 3 Add dilute, followed by silver nitrate, solution Test 4 Add dilute HCl, followed by barium chloride, BaCl 2 solution S O D I U M C A R B O N A T E S O D I U M N I T R A T E Result 1 Efferves cence Result 2 No change Result 3 No change Result 4 No change Result 1 No change Result 2 Brown ring Result 3 No change Result 4 No change

SODIUM CHLORIDE AND SODIUM SULPHATE

Test 1 Add dilute (any acid) Test 2 add dilute H 2 SO 4 followed by FeSO 4 solution. Carefully add 1of concentrated H 2 SO 4 Test 3 Add dilute, followed by silver nitrate, solution Test 4 Add dilute HCl, followed by barium chloride, BaCl 2 solution S O D I U M C H L O R I D E S O D I U M S U L P H A T E Result 1 No change Result 2 No change Result 3 White precipitate Result 4 No change Result 1 No change Result 2 No change Result 3 No change Result 4 White precipitate

Exercise : Page 144: Quick Review A Page 147: Quick Review B