JK-TK/Newdata huggingface dataset:
Observation Colour change from black to brown. Excess carbon (II)oxide burn with a blue flame. Flame K Dry carbon(II)oxide
11 Explanation Carbon is a reducing agent. It is used to reduce metal oxide ores to metal, itself oxidized to carbon(IV)oxide gas. Carbon(II)Oxide reduces black copper(II)oxide to brown copper metal Chemical Equation CuO(s) + CO(g) -> Cu(s) + CO2(g) (black) (brown) PbO(s) + CO(g) -> Pb(s) + CO2(g) (brown when hot/ (grey) yellow when cool) ZnO(s) + CO(g) -> Zn(s) + CO2(g) (yellow when hot/ (grey) white when cool) Fe2O3(s) + 3CO(s) -> 2Fe(s) + 3CO2(g) (brown when hot/cool (grey) Fe3O4 (s) + 4CO(g) -> 3Fe(s) + 4CO2(g) (brown when hot/cool (grey) These reaction are used during the extraction of many metals from their ore. 9. Carbon (II) oxide is a pollutant. Explain. Carbon(II)oxide is highly poisonous/toxic.It preferentially combine with haemoglobin to form stable carboxyhaemoglobin in the blood instead of oxyhaemoglobin.This reduces the free haemoglobin in the blood causing nausea , coma then death. 10.The diagram below show a burning charcoal stove/burner/jiko. Use it to answer the questions that follow. 12 Explain the changes that take place in the burner Explanation Charcoal stove has air holes through which air enters. Air oxidizes carbon to carbon(IV)oxide gas at region I. This reaction is exothermic(-∆H) producing more heat. Chemical equation C(s) + O2(g) -> CO2(g) Carbon(IV)oxide gas formed rises up to meet more charcoal which reduces it to Carbon(II)oxide gas. Chemical equation 2CO2 (g) + O2(g) -> 2CO (g) At the top of burner in region II, Carbon (II)oxide gas is further oxidized to Carbon(IV)oxide gas if there is plenty of air but escape if the air is limited poisoning the living things around.
This reaction is exothermic(-∆H) producing more heat. Chemical equation C(s) + O2(g) -> CO2(g) Carbon(IV)oxide gas formed rises up to meet more charcoal which reduces it to Carbon(II)oxide gas. Chemical equation 2CO2 (g) + O2(g) -> 2CO (g) At the top of burner in region II, Carbon (II)oxide gas is further oxidized to Carbon(IV)oxide gas if there is plenty of air but escape if the air is limited poisoning the living things around. Chemical equation 2CO (g) + O2(g) -> 2CO2 (g) (excess air) 11.Describe the test for the presence of carbon(II)oxide gas. Experiment Burn/Ignite the pure sample of the gas. Pass/Bubble the products into lime water/Calcium hydroxide . Observation Colourless gas burns with a blue flame. A white precipitate is formed that dissolve on further bubbling of the products. Chemical equation 2CO (g) + O2(g) -> 2CO2 (g) (gas burns with blue flame) Chemical equation Ca(OH) 2 (aq) + CO2 (g) -> CaCO3 (s) + H2O(l) Chemical equation CO2 (g) + CaCO3 (s) + H2O(l) -> Ca(HCO3) 2 (aq) 12. State the main uses of carbon (II)oxide gas. (i) As a fuel /water gas (ii)As a reducing agent in the blast furnace for extracting iron from iron ore(Magnetite/Haematite) (iii)As a reducing agent in extraction of Zinc from Zinc ore/Zinc blende (iv) As a reducing agent in extraction of Lead from Lead ore/Galena (v) As a reducing agent in extraction of Copper from Copper iron sulphide/Copper pyrites. 13 (iii)Carbonate(IV) (CO32-)and hydrogen carbonate(IV(HCO3-) 1.Carbonate (IV) (CO32-) are normal salts derived from carbonic(IV)acid (H2CO3) and hydrogen carbonate (IV) (HCO3-) are acid salts derived from carbonic(IV)acid.
State the main uses of carbon (II)oxide gas. (i) As a fuel /water gas (ii)As a reducing agent in the blast furnace for extracting iron from iron ore(Magnetite/Haematite) (iii)As a reducing agent in extraction of Zinc from Zinc ore/Zinc blende (iv) As a reducing agent in extraction of Lead from Lead ore/Galena (v) As a reducing agent in extraction of Copper from Copper iron sulphide/Copper pyrites. 13 (iii)Carbonate(IV) (CO32-)and hydrogen carbonate(IV(HCO3-) 1.Carbonate (IV) (CO32-) are normal salts derived from carbonic(IV)acid (H2CO3) and hydrogen carbonate (IV) (HCO3-) are acid salts derived from carbonic(IV)acid. Carbonic(IV)acid(H2CO3) is formed when carbon(IV)oxide gas is bubbled in water. It is a dibasic acid with two ionizable hydrogens. H2CO3(aq) ->2H+(aq) + CO32-(aq) H2CO3(aq) -> H+(aq) + HCO3 - (aq) 2.Carbonate (IV) (CO32-) are insoluble in water except Na2CO3 , K2CO3 and (NH4)2CO3 3.Hydrogen carbonate (IV) (HCO3-) are soluble in water. Only five hydrogen carbonates exist. Na HCO3 , KHCO3 ,NH4HCO3 Ca(HCO3)2 and Mg(HCO3)2 Ca(HCO3)2 and Mg(HCO3)2 exist only in aqueous solutions. 3.The following experiments show the effect of heat on Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) salts: Experiment In a clean dry test tube place separately about 1.0 of the following: Zinc(II)carbonate(IV), sodium hydrogen carbonate(IV), sodium carbonate(IV), Potassium carbonate(IV) ammonium carbonate(IV), potassium hydrogen carbonate(IV), Lead(II)carbonate(IV), Iron(II)carbonate(IV), and copper(II)carbonate(IV). Heat each portion gently the strongly. Test any gases produced with lime water.
3.The following experiments show the effect of heat on Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) salts: Experiment In a clean dry test tube place separately about 1.0 of the following: Zinc(II)carbonate(IV), sodium hydrogen carbonate(IV), sodium carbonate(IV), Potassium carbonate(IV) ammonium carbonate(IV), potassium hydrogen carbonate(IV), Lead(II)carbonate(IV), Iron(II)carbonate(IV), and copper(II)carbonate(IV). Heat each portion gently the strongly. Test any gases produced with lime water. Observation (i)Colorless droplets form on the cooler parts of test tube in case of sodium carbonate(IV) and Potassium carbonate(IV). (ii)White residue/solid left in case of sodium hydrogen carbonate(IV), sodium carbonate(IV), Potassium carbonate(IV) and potassium hydrogen carbonate(IV). (iii)Colour changes from blue/green to black in case of copper(II)carbonate(IV). (iv) Colour changes from green to brown/yellow in case of Iron (II)carbonate(IV). (v) Colour changes from white when cool to yellow when hot in case of Zinc (II) carbonate(IV). (vi) Colour changes from yellow when cool to brown when hot in case of Lead (II) carbonate(IV). (vii)Colourless gas produced that forms a white precipitate with lime water in all cases. Explanation 1. Sodium carbonate(IV) and Potassium carbonate(IV) exist as hydrated salts with 10 molecules of water of crystallization that condenses and collects on cooler parts of test tube as a colourless liquid. Chemical equation Na2CO3 .10H2O(s) -> Na2CO3 (s) + 10H2O(l)
14 K2CO3 .10H2O(s) -> K2CO3 (s) + 10H2O(l) 2. Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) salts decompose on heating except Sodium carbonate(IV) and Potassium carbonate(IV). (a) Sodium hydrogen carbonate(IV) and Potassium hydrogen carbonate(IV) decompose on heating to form sodium carbonate(IV) and Potassium carbonate(IV).Water and carbon(IV)oxide gas are also produced.
Chemical equation Na2CO3 .10H2O(s) -> Na2CO3 (s) + 10H2O(l)
14 K2CO3 .10H2O(s) -> K2CO3 (s) + 10H2O(l) 2. Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) salts decompose on heating except Sodium carbonate(IV) and Potassium carbonate(IV). (a) Sodium hydrogen carbonate(IV) and Potassium hydrogen carbonate(IV) decompose on heating to form sodium carbonate(IV) and Potassium carbonate(IV).Water and carbon(IV)oxide gas are also produced. Chemical equation 2NaHCO3 (s) -> Na2CO3 (s) + H2O(l) + CO2 (g) (white) (white) 2KHCO3 (s) -> K2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (b) Calcium hydrogen carbonate(IV) and Magnesium hydrogen carbonate(IV) decompose on heating to form insoluble Calcium carbonate(IV) and Magnesium carbonate(IV).Water and carbon(IV)oxide gas are also produced. Chemical equation Ca(HCO3)2 (aq) -> CaCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) Mg(HCO3)2 (aq) -> MgCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) (c) Ammonium hydrogen carbonate(IV) decompose on heating to form ammonium carbonate(IV) .Water and carbon(IV)oxide gas are also produced. Chemical equation 2NH4HCO3 (s) -> (NH4)2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (d)All other carbonates decompose on heating to form the metal oxide and produce carbon(IV)oxide gas e.g.
Chemical equation 2NaHCO3 (s) -> Na2CO3 (s) + H2O(l) + CO2 (g) (white) (white) 2KHCO3 (s) -> K2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (b) Calcium hydrogen carbonate(IV) and Magnesium hydrogen carbonate(IV) decompose on heating to form insoluble Calcium carbonate(IV) and Magnesium carbonate(IV).Water and carbon(IV)oxide gas are also produced. Chemical equation Ca(HCO3)2 (aq) -> CaCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) Mg(HCO3)2 (aq) -> MgCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) (c) Ammonium hydrogen carbonate(IV) decompose on heating to form ammonium carbonate(IV) .Water and carbon(IV)oxide gas are also produced. Chemical equation 2NH4HCO3 (s) -> (NH4)2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (d)All other carbonates decompose on heating to form the metal oxide and produce carbon(IV)oxide gas e.g. Chemical equation MgCO3 (s) -> MgO (s) + CO2 (g) (white solid) (white solid) Chemical equation BaCO3 (s) -> BaO (s) + CO2 (g) (white solid) (white solid) Chemical equation CaCO3 (s) -> CaO (s) + CO2 (g) (white solid) (white solid) Chemical equation CuCO3 (s) -> CuO (s) + CO2 (g) (blue/green solid) (black solid) Chemical equation ZnCO3 (s) -> ZnO (s) + CO2 (g) (white solid) (white solid when cool/
15 Yellow solid when hot) Chemical equation PbCO3 (s) -> PbO (s) + CO2 (g) (white solid) (yellow solid when cool/ brown solid when hot) 4.The following experiments show the presence of Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) ions in sample of a salt: (a)Using Lead(II) nitrate(V) I.
Chemical equation Ca(HCO3)2 (aq) -> CaCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) Mg(HCO3)2 (aq) -> MgCO3 (s) + H2O(l) + CO2 (g) (Colourless solution) (white) (c) Ammonium hydrogen carbonate(IV) decompose on heating to form ammonium carbonate(IV) .Water and carbon(IV)oxide gas are also produced. Chemical equation 2NH4HCO3 (s) -> (NH4)2CO3 (s) + H2O(l) + CO2 (g) (white) (white) (d)All other carbonates decompose on heating to form the metal oxide and produce carbon(IV)oxide gas e.g. Chemical equation MgCO3 (s) -> MgO (s) + CO2 (g) (white solid) (white solid) Chemical equation BaCO3 (s) -> BaO (s) + CO2 (g) (white solid) (white solid) Chemical equation CaCO3 (s) -> CaO (s) + CO2 (g) (white solid) (white solid) Chemical equation CuCO3 (s) -> CuO (s) + CO2 (g) (blue/green solid) (black solid) Chemical equation ZnCO3 (s) -> ZnO (s) + CO2 (g) (white solid) (white solid when cool/
15 Yellow solid when hot) Chemical equation PbCO3 (s) -> PbO (s) + CO2 (g) (white solid) (yellow solid when cool/ brown solid when hot) 4.The following experiments show the presence of Carbonate (IV) (CO32-) and Hydrogen carbonate (IV) (HCO3-) ions in sample of a salt: (a)Using Lead(II) nitrate(V) I. Using a portion of salt solution in a test tube .add four drops of Lead(II)nitrate(V)solution.Preserve. Observation inference White precipitate/ppt CO32- ,SO32- ,SO42- ,Cl- - II. To the preserved solution ,add six drops of dilutte nitric(V)acid. Preserve.
Observation inference White precipitate/ppt CO32- ,SO32- ,SO42- ,Cl- - II. To the preserved solution ,add six drops of dilutte nitric(V)acid. Preserve. Observation inference White precipitate/ppt persists White precipitate/ppt dissolves SO42- ,Cl- CO32- ,SO32- II. To the preserved sample( that forms a precipitate ),heat to boil. Observation inference White precipitate/ppt persists White precipitate/ppt dissolves SO42- Cl- II. To the preserved sample( that do not form a precipitate ),add three drops of acidified potassium manganate(VII)/lime water Observation inference Effervescence/bubbles/fizzing colourless gas produced Acidified KMnO4 decolorized/no white precipitate on lime water Effervescence/bubbles/fizzing colourless gas produced Acidified KMnO4 not decolorized/ white precipitate on lime water SO32- CO32-
16 Experiments/Observations: (b)Using Barium(II)nitrate(V)/ Barium(II)chloride I. To about 5cm3 of a salt solution in a test tube add four drops of Barium(II) nitrate (V) / Barium(II)chloride. Preserve. Observation Inference White precipitate/ppt SO42- , SO32- , CO32- ions II. To the preserved sample in (I) above, add six drops of 2M nitric(V) acid . Preserve. Observation 1 Observation Inference White precipitate/ppt persists SO42- , ions Observation 2 Observation Inference White precipitate/ppt dissolves SO32- , CO32- , ions III.To the preserved sample observation 2 in (II) above, add 4 drops of acidified potassium manganate(VII) /dichromate(VI).
To the preserved sample in (I) above, add six drops of 2M nitric(V) acid . Preserve. Observation 1 Observation Inference White precipitate/ppt persists SO42- , ions Observation 2 Observation Inference White precipitate/ppt dissolves SO32- , CO32- , ions III.To the preserved sample observation 2 in (II) above, add 4 drops of acidified potassium manganate(VII) /dichromate(VI). Observation 1 Observation Inference (i)acidified potassium manganate(VII)decolorized (ii)Orange colour of acidified potassium dichromate(VI) turns to green SO32- ions Observation 2 Observation Inference (i)acidified potassium manganate(VII) not decolorized (ii)Orange colour of acidified potassium dichromate(VI) does not turns to green CO32- ions Explanations Using Lead(II)nitrate(V)
17 (i)Lead(II)nitrate(V) solution reacts with chlorides(Cl-), Sulphate (VI) salts (SO42- ), Sulphate (IV)salts (SO32-) and carbonates(CO32-) to form the insoluble white precipitate of Lead(II)chloride, Lead(II)sulphate(VI), Lead(II) sulphate (IV) and Lead(II)carbonate(IV). Chemical/ionic equation: Pb2+(aq) + Cl- (aq) -> PbCl2(s) Pb2+(aq) + SO42+ (aq) -> PbSO4 (s) Pb2+(aq) + SO32+ (aq) -> PbSO3 (s) Pb2+(aq) + CO32+ (aq) -> PbCO3 (s) (ii)When the insoluble precipitates are acidified with nitric(V) acid, - Lead(II)chloride and Lead(II)sulphate(VI) do not react with the acid and thus their white precipitates remain/ persists. - Lead(II) sulphate (IV) and Lead(II)carbonate(IV) reacts with the acid to form soluble Lead(II) nitrate (V) and produce/effervesces/fizzes/bubbles out sulphur(IV)oxide and carbon(IV)oxide gases respectively. .
Chemical/ionic equation: Pb2+(aq) + Cl- (aq) -> PbCl2(s) Pb2+(aq) + SO42+ (aq) -> PbSO4 (s) Pb2+(aq) + SO32+ (aq) -> PbSO3 (s) Pb2+(aq) + CO32+ (aq) -> PbCO3 (s) (ii)When the insoluble precipitates are acidified with nitric(V) acid, - Lead(II)chloride and Lead(II)sulphate(VI) do not react with the acid and thus their white precipitates remain/ persists. - Lead(II) sulphate (IV) and Lead(II)carbonate(IV) reacts with the acid to form soluble Lead(II) nitrate (V) and produce/effervesces/fizzes/bubbles out sulphur(IV)oxide and carbon(IV)oxide gases respectively. . Chemical/ionic equation: PbSO3 (s) + 2H+(aq) -> H2 O (l) + Pb2+(aq) + SO2 (g) PbCO3 (s) + 2H+(aq) -> H2 O (l) + Pb2+(aq) + CO2 (g) (iii)When Lead(II)chloride and Lead(II)sulphate(VI) are heated/warmed; - Lead(II)chloride dissolves in hot water/on boiling(recrystallizes on cooling) - Lead(II)sulphate(VI) do not dissolve in hot water thus its white precipitate persists/remains on heating/boiling. (iv)When sulphur(IV)oxide and carbon(IV)oxide gases are produced; - sulphur(IV)oxide will decolorize acidified potassium manganate(VII) and / or Orange colour of acidified potassium dichromate(VI) will turns to green. Carbon(IV)oxide will not.
Chemical/ionic equation: PbSO3 (s) + 2H+(aq) -> H2 O (l) + Pb2+(aq) + SO2 (g) PbCO3 (s) + 2H+(aq) -> H2 O (l) + Pb2+(aq) + CO2 (g) (iii)When Lead(II)chloride and Lead(II)sulphate(VI) are heated/warmed; - Lead(II)chloride dissolves in hot water/on boiling(recrystallizes on cooling) - Lead(II)sulphate(VI) do not dissolve in hot water thus its white precipitate persists/remains on heating/boiling. (iv)When sulphur(IV)oxide and carbon(IV)oxide gases are produced; - sulphur(IV)oxide will decolorize acidified potassium manganate(VII) and / or Orange colour of acidified potassium dichromate(VI) will turns to green. Carbon(IV)oxide will not. Chemical equation: 5SO32-(aq) + 2MnO4- (aq) +6H+(aq) -> 5SO42-(aq) + 2Mn2+(aq) + 3H2O(l) (purple) (colourless) 3SO32-(aq) + Cr2O72-(aq) +8H+(aq) -> 3SO42-(aq) + 2Cr3+(aq) + 4H2O(l) (Orange) (green) - Carbon(IV)oxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place. Sulphur(IV)oxide will not. Chemical equation: Ca(OH)2(aq) + CO2 (g) -> CaCO3(s) + H2O(l) These tests should be done immediately after acidifying to ensure the gases produced react with the oxidizing agents/lime water.
Chemical equation: 5SO32-(aq) + 2MnO4- (aq) +6H+(aq) -> 5SO42-(aq) + 2Mn2+(aq) + 3H2O(l) (purple) (colourless) 3SO32-(aq) + Cr2O72-(aq) +8H+(aq) -> 3SO42-(aq) + 2Cr3+(aq) + 4H2O(l) (Orange) (green) - Carbon(IV)oxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place. Sulphur(IV)oxide will not. Chemical equation: Ca(OH)2(aq) + CO2 (g) -> CaCO3(s) + H2O(l) These tests should be done immediately after acidifying to ensure the gases produced react with the oxidizing agents/lime water. 18 Using Barium(II)nitrate(V)/ Barium(II)Chloride (i)Barium(II)nitrate(V) and/ or Barium(II)chloride solution reacts with Sulphate (VI) salts (SO42- ), Sulphate (IV)salts (SO32-) and carbonates(CO32-) to form the insoluble white precipitate of Barium(II)sulphate(VI), Barium(II) sulphate (IV) and Barium(II)carbonate(IV). Chemical/ionic equation: Ba2+(aq) + SO42+ (aq) -> BaSO4 (s) Ba2+(aq) + SO32+ (aq) -> BaSO3 (s) Ba2+(aq) + CO32+ (aq) -> BaCO3 (s) (ii)When the insoluble precipitates are acidified with nitric(V) acid, - Barium (II)sulphate(VI) do not react with the acid and thus its white precipitates remain/ persists. - Barium(II) sulphate (IV) and Barium(II)carbonate(IV) reacts with the acid to form soluble Barium(II) nitrate (V) and produce /effervesces /fizzes/ bubbles out sulphur(IV)oxide and carbon(IV)oxide gases respectively. .
Chemical/ionic equation: Ba2+(aq) + SO42+ (aq) -> BaSO4 (s) Ba2+(aq) + SO32+ (aq) -> BaSO3 (s) Ba2+(aq) + CO32+ (aq) -> BaCO3 (s) (ii)When the insoluble precipitates are acidified with nitric(V) acid, - Barium (II)sulphate(VI) do not react with the acid and thus its white precipitates remain/ persists. - Barium(II) sulphate (IV) and Barium(II)carbonate(IV) reacts with the acid to form soluble Barium(II) nitrate (V) and produce /effervesces /fizzes/ bubbles out sulphur(IV)oxide and carbon(IV)oxide gases respectively. . Chemical/ionic equation: BaSO3 (s) + 2H+(aq) -> H2 O (l) + Ba2+(aq) + SO2 (g) BaCO3 (s) + 2H+(aq) -> H2 O (l) + Ba2+(aq) + CO2 (g) (iii) When sulphur(IV)oxide and carbon(IV)oxide gases are produced; - sulphur(IV)oxide will decolorize acidified potassium manganate(VII) and / or Orange colour of acidified potassium dichromate(VI) will turns to green. Carbon(IV)oxide will not. Chemical equation: 5SO32-(aq) + 2MnO4- (aq) +6H+(aq) -> 5SO42-(aq) + 2Mn2+(aq) + 3H2O(l) (purple) (colourless) 3SO32-(aq) + Cr2O72-(aq) +8H+(aq) -> 3SO42-(aq) + 2Cr3+(aq) + 4H2O(l) (Orange) (green) - Carbon(IV)oxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place. Sulphur(IV)oxide will not.
Carbon(IV)oxide will not. Chemical equation: 5SO32-(aq) + 2MnO4- (aq) +6H+(aq) -> 5SO42-(aq) + 2Mn2+(aq) + 3H2O(l) (purple) (colourless) 3SO32-(aq) + Cr2O72-(aq) +8H+(aq) -> 3SO42-(aq) + 2Cr3+(aq) + 4H2O(l) (Orange) (green) - Carbon(IV)oxide forms an insoluble white precipitate of calcium carbonate if three drops of lime water are added into the reaction test tube when effervescence is taking place. Sulphur(IV)oxide will not. Chemical equation: Ca(OH)2(aq) + CO2 (g) -> CaCO3(s) + H2O(l)
19 These tests should be done immediately after acidifying to ensure the gases produced react with the oxidizing agents/lime water. (iii) Sodium carbonate(IV) (Na2CO3) (a)Extraction of sodium carbonate from soda ash Sodium carbonate naturally occurs in Lake Magadi in Kenya as Trona.trona is the double salt ; sodium sesquicarbonate. NaHCO3 .Na2CO3 .H2O.It is formed from the volcanic activity that takes place in Lake Naivasha, Nakuru ,Bogoria and Elementeita .All these lakes drain into Lake Magadi through underground rivers. Lake Magadi has no outlet. Solubility of Trona decrease with increase in temperature.High temperature during the day causes trona to naturally crystallize .It is mechanically scooped/dredged/dug and put in a furnace. Inside the furnace, trona decompose into soda ash/sodium carbonate.
Lake Magadi has no outlet. Solubility of Trona decrease with increase in temperature.High temperature during the day causes trona to naturally crystallize .It is mechanically scooped/dredged/dug and put in a furnace. Inside the furnace, trona decompose into soda ash/sodium carbonate. Chemical equation 2NaHCO3 .Na2CO3 .H2O (s) -> 3Na2CO3 (s) + 5H2O(l) + CO2 (g) (trona) (soda ash) Soda ash is then bagged and sold as Magadi soda.It is mainly used: (i)in making glass to lower the melting point of raw materials (sand/SiO2 from 1650oC and CaO from 2500oC to around 1500oC) (ii)in softening hard water (iii)in the manufacture of soapless detergents. (iv)Swimming pool “pH increaser” Sodium chloride is also found dissolved in the lake. Solubility of sodium chloride decrease with decreases in temperature/ sodium chloride has lower solubility at lower temperatures. When temperatures decrease at night it crystallize out .The crystals are then mechanically dug/dredged /scooped then packed for sale as animal/cattle feeds and seasoning food. Summary flow diagram showing the extraction of Soda ash from Trona Sodium chloride and Trona dissolved in the sea Natural fractional crystallization Crystals of Trona (Day time) Dredging /scooping/ digging Crushing Furnace (Heating) Carbon(IV) oxide
20 b)The Solvay process for industrial manufacture of sodium carbonate(IV) (i)Raw materials. -Brine /Concentrated Sodium chloride from salty seas/lakes. -Ammonia gas from Haber. -Limestone /Calcium carbonate from chalk /limestone rich rocks. -Water from rivers/lakes. (ii)Chemical processes Ammonia gas is passed up to meet a downward flow of sodium chloride solution / brine to form ammoniated brine/ammoniacal brine mixture in the ammoniated brine chamber The ammoniated brine mixture is then pumped up, atop the carbonator/ solvay tower. In the carbonator/ solvay tower, ammoniated brine/ammoniacal brine mixture slowly trickle down to meet an upward flow of carbon(IV)oxide gas.