JK-TK/Newdata huggingface dataset:
M(l) -> M+(l) + e (for cations from molten electrolytes) M(s) -> M+(aq) + e (for cations from electrolytes in aqueous state / solution / dissolved in water) The neutral atoms /molecules form the products of electrolysis at the anode. This is called discharge at anode 10. During electrolysis, free cations are attracted to the cathode where they gain /accept/acquire electrons to form neutral atoms/molecules. X+ (aq) + 2e -> X(s) (for cations from electrolytes in aqueous state / solution / dissolved in water) 2X+ (l) + 2e -> X (l) (for cations from molten electrolytes) The neutral atoms /molecules form the products of electrolysis at the cathode. This is called discharge at cathode. 11. The below set up shows an electrolytic cell. 3 BatteryAnode(+)Cathode(-)ElectrolyteSimple set up of electrolytic cellGaseous product at anodeGaseous product at cathode 12. For a compound /salt containing only two ion/binary salt the products of electrolysis in an electrolytic cell can be determined as in the below examples: a)To determine the products of electrolysis of molten Lead(II)chloride (i)Decomposition of electrolyte into free ions; PbCl2 (l) -> Pb 2+(l) + 2Cl-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); Pb 2+(l) + 2e -> Pb (l) (Cation / Pb 2+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Cl-(l) -> Cl2 (g) + 2e (Anion / Cl- donate/lose electrons to form free atom then a gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid lead metal. II.At the anode pale green chlorine gas.
3 BatteryAnode(+)Cathode(-)ElectrolyteSimple set up of electrolytic cellGaseous product at anodeGaseous product at cathode 12. For a compound /salt containing only two ion/binary salt the products of electrolysis in an electrolytic cell can be determined as in the below examples: a)To determine the products of electrolysis of molten Lead(II)chloride (i)Decomposition of electrolyte into free ions; PbCl2 (l) -> Pb 2+(l) + 2Cl-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); Pb 2+(l) + 2e -> Pb (l) (Cation / Pb 2+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Cl-(l) -> Cl2 (g) + 2e (Anion / Cl- donate/lose electrons to form free atom then a gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid lead metal. II.At the anode pale green chlorine gas. b)To determine the products of electrolysis of molten Zinc bromide
4 (i)Decomposition of electrolyte into free ions; ZnBr2 (l) -> Zn 2+(l) + 2Br-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); Zn 2+(l) + 2e -> Zn(l) (Cation / Zn2+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Br-(l) -> Br2 (g) + 2e (Anion / Br- donate/lose electrons to form free atom then a liquid molecule which change to gas on heating) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid Zinc metal. II.At the anode red bromine liquid / red/brown bromine gas.
II.At the anode pale green chlorine gas. b)To determine the products of electrolysis of molten Zinc bromide
4 (i)Decomposition of electrolyte into free ions; ZnBr2 (l) -> Zn 2+(l) + 2Br-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); Zn 2+(l) + 2e -> Zn(l) (Cation / Zn2+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Br-(l) -> Br2 (g) + 2e (Anion / Br- donate/lose electrons to form free atom then a liquid molecule which change to gas on heating) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid Zinc metal. II.At the anode red bromine liquid / red/brown bromine gas. c)To determine the products of electrolysis of molten sodium chloride (i)Decomposition of electrolyte into free ions; NaCl (l) -> Na +(l) + Cl-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); 2Na+(l) + 2e -> Na (l) (Cation / Na+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Cl-(l) -> Cl2 (g) + 2e (Anion / Cl- donate/lose electrons to form free atom then a gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid sodium metal. II.At the anode pale green chlorine gas.
II.At the anode red bromine liquid / red/brown bromine gas. c)To determine the products of electrolysis of molten sodium chloride (i)Decomposition of electrolyte into free ions; NaCl (l) -> Na +(l) + Cl-(l) (Compound decomposed into free cation and anion in liquid state) (ii)At the cathode/negative electrode(-); 2Na+(l) + 2e -> Na (l) (Cation / Na+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 2Cl-(l) -> Cl2 (g) + 2e (Anion / Cl- donate/lose electrons to form free atom then a gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid sodium metal. II.At the anode pale green chlorine gas. d)To determine the products of electrolysis of molten Aluminium (III)oxide (i)Decomposition of electrolyte into free ions; Al2O3 (l) -> 2Al 3+(l) + 3O2-(l) (Compound decomposed into free cation and anion in liquid state)
5 (ii)At the cathode/negative electrode(-); 4Al 3+ (l) + 12e -> 4Al (l) (Cation / Al 3+ gains / accepts / acquires electrons to form free atom) (iii)At the anode/positive electrode(+); 6O2-(l) -> 3O2 (g) + 12e (Anion /6O2- donate/lose 12 electrons to form free atom then three gas molecule) (iv)Products of electrolysis therefore are; I.At the cathode grey beads /solid aluminium metal. II.At the anode colourless gas that relights/rekindles glowing splint. 13.In industries electrolysis has the following uses/applications: (a)Extraction of reactive metals from their ores. Potassium, sodium ,magnesium, and aluminium are extracted from their ores using electrolytic methods. (b)Purifying copper after exraction from copper pyrites ores. Copper obtained from copper pyrites ores is not pure.
Potassium, sodium ,magnesium, and aluminium are extracted from their ores using electrolytic methods. (b)Purifying copper after exraction from copper pyrites ores. Copper obtained from copper pyrites ores is not pure. After extraction, the copper is refined by electrolysing copper(II)sulphate(VI) solution using the impure copper as anode and a thin strip of pure copper as cathode. Electrode ionization take place there: (i)At the cathode; Cu2+ (aq) + 2e -> Cu(s) (Pure copper deposits on the strip (ii)At the anode; Cu(s) ->Cu2+ (aq) + 2e (impure copper erodes/dissolves) (c)Electroplating The label EPNS(Electro Plated Nickel Silver) on some steel/metallic utensils mean they are plated/coated with silver and/or Nickel to improve their appearance(add their aesthetic value)and prevent/slow corrosion(rusting of iron). Electroplating is the process of coating a metal with another metal using an electric current. During electroplating, the cathode is made of the metal to be coated/impure. Example: During the electroplating of a spoon with silver (i)the spoon/impure is placed as the cathode(negative terminal of battery) (ii)the pure silver is placed as the anode(positive terminal of battery) (iii)the pure silver erodes/ionizes/dissociates to release electrons: Ag(s) ->Ag+ (aq) + e (impure silver erodes/dissolves)
6 (iv) silver (Ag+)ions from electrolyte gain electrons to form pure silver deposits / coat /cover the spoon/impure Ag+ (aq) + e ->Ag(s) (pure silver deposits /coat/cover on spoon)
CARBON AND ITS COMPOUNDS Carbon is an element in Group IV(Group 4)of the Periodic table .It has atomic number 6 and electronic configuration 2:4 and thus has four valence electrons (tetravalent).It does not easily ionize but forms strong covalent bonds with other elements including itself. (a)Occurrence Carbon mainly naturally occurs as: (i)allotropes of carbon i.e graphite, diamond and fullerenes. (ii)amorphous carbon in coal, peat ,charcoal and coke.
Example: During the electroplating of a spoon with silver (i)the spoon/impure is placed as the cathode(negative terminal of battery) (ii)the pure silver is placed as the anode(positive terminal of battery) (iii)the pure silver erodes/ionizes/dissociates to release electrons: Ag(s) ->Ag+ (aq) + e (impure silver erodes/dissolves)
6 (iv) silver (Ag+)ions from electrolyte gain electrons to form pure silver deposits / coat /cover the spoon/impure Ag+ (aq) + e ->Ag(s) (pure silver deposits /coat/cover on spoon)
CARBON AND ITS COMPOUNDS Carbon is an element in Group IV(Group 4)of the Periodic table .It has atomic number 6 and electronic configuration 2:4 and thus has four valence electrons (tetravalent).It does not easily ionize but forms strong covalent bonds with other elements including itself. (a)Occurrence Carbon mainly naturally occurs as: (i)allotropes of carbon i.e graphite, diamond and fullerenes. (ii)amorphous carbon in coal, peat ,charcoal and coke. (iii)carbon(IV)oxide gas accounting 0.03% by volume of normal air in the atmosphere. (b)Allotropes of Carbon Carbon naturally occur in two main crystalline allotropic forms, carbon-graphite and carbon-diamond Carbon-diamond Carbon-graphite Shiny crystalline solid Black/dull crystalline solid Has a very high melting/boiling point because it has a very closely packed giant tetrahedral structure joined by strong covalent bonds Has a high melting/boiling point because it has a very closely packed giant hexagonal planar structure joined by strong covalent bonds Has very high density(Hardest known Soft
2 natural substance) Abrassive Slippery Poor electrical conductor because it has no free delocalized electrons Good electrical conductor because it has free 4th valency delocalized electrons Is used in making Jewels, drilling and cutting metals Used in making Lead-pencils,electrodes in batteries and as a lubricant Has giant tetrahedral structure Has giant hexagonal planar structure c)Properties of Carbon (i)Physical properties of carbon Carbon occur widely and naturally as a black solid It is insoluble in water but soluble in carbon disulphide and organic solvents.
(ii)amorphous carbon in coal, peat ,charcoal and coke. (iii)carbon(IV)oxide gas accounting 0.03% by volume of normal air in the atmosphere. (b)Allotropes of Carbon Carbon naturally occur in two main crystalline allotropic forms, carbon-graphite and carbon-diamond Carbon-diamond Carbon-graphite Shiny crystalline solid Black/dull crystalline solid Has a very high melting/boiling point because it has a very closely packed giant tetrahedral structure joined by strong covalent bonds Has a high melting/boiling point because it has a very closely packed giant hexagonal planar structure joined by strong covalent bonds Has very high density(Hardest known Soft
2 natural substance) Abrassive Slippery Poor electrical conductor because it has no free delocalized electrons Good electrical conductor because it has free 4th valency delocalized electrons Is used in making Jewels, drilling and cutting metals Used in making Lead-pencils,electrodes in batteries and as a lubricant Has giant tetrahedral structure Has giant hexagonal planar structure c)Properties of Carbon (i)Physical properties of carbon Carbon occur widely and naturally as a black solid It is insoluble in water but soluble in carbon disulphide and organic solvents. It is a poor electrical and thermal conductor. (ii)Chemical properties of carbon I. Burning Experiment Introduce a small piece of charcoal on a Bunsen flame then lower it into a gas jar containing Oxygen gas. Put three drops of water. Swirl. Test the solution with blue and red litmus papers. Observation -Carbon chars then burns with a blue flame -Colourless and odourless gas produced -Solution formed turn blue litmus paper faint red. Red litmus paper remains red. Explanation Carbon burns in air and faster in Oxygen with a blue non-sooty/non-smoky flame forming Carbon (IV) oxide gas. Carbon burns in limited supply of air with a blue non-sooty/non-smoky flame forming Carbon (IV) oxide gas. Carbon (IV) oxide gas dissolve in water to form weak acidic solution of Carbonic (IV)acid.
Explanation Carbon burns in air and faster in Oxygen with a blue non-sooty/non-smoky flame forming Carbon (IV) oxide gas. Carbon burns in limited supply of air with a blue non-sooty/non-smoky flame forming Carbon (IV) oxide gas. Carbon (IV) oxide gas dissolve in water to form weak acidic solution of Carbonic (IV)acid. Chemical Equation C(s) + O2(g) -> CO2(g) (in excess air) 2C(s) + O2(g) -> 2CO(g) (in limited air) CO2(g) + H2O (l) -> H2CO3 (aq) (very weak acid) II. Reducing agent Experiment Mix thoroughly equal amounts of powdered charcoal and copper (II)oxide into a crucible. Heat strongly. Observation Colour change from black to brown Explanation
3 Carbon is a reducing agent. For ages it has been used to reducing metal oxide ores to metal, itself oxidized to carbon(IV)oxide gas.
Heat strongly. Observation Colour change from black to brown Explanation
3 Carbon is a reducing agent. For ages it has been used to reducing metal oxide ores to metal, itself oxidized to carbon(IV)oxide gas. Carbon reduces black copper(II)oxide to brown copper metal Chemical Equation 2CuO(s) + C(s) -> 2Cu(s) + CO2(g) (black) (brown) 2PbO(s) + C(s) -> 2Pb(s) + CO2(g) (brown when hot/ (grey) yellow when cool) 2ZnO(s) + C(s) -> 2Zn(s) + CO2(g) (yellow when hot/ (grey) white when cool) Fe2O3(s) + 3C(s) -> 2Fe(s) + 3CO2(g) (brown when hot/cool (grey) Fe3O4 (s) + 4C(s) -> 3Fe(s) + 4CO2(g) (brown when hot/cool (grey)
4 B: COMPOUNDS OF CARBON The following are the main compounds of Carbon (i)Carbon(IV)Oxide(CO2) (ii)Carbon(II)Oxide(CO) (iii)Carbonate(IV) (CO32-)and hydrogen carbonate(IV(HCO3-) (iv)Sodium carbonate(Na2CO3) (i) Carbon(IV)Oxide (CO2) (a)Occurrence Carbon(IV)oxide is found: -in the air /atmosphere as 0.03% by volume. -a solid carbon(IV)oxide mineral in Esageri near Eldame Ravine and Kerita near Limuru in Kenya. (b)School Laboratory preparation In the school laboratory carbon(IV)oxide can be prepared in the school laboratory from the reaction of marble chips(CaCO3)or sodium hydrogen carbonate(NaHCO3) with dilute hydrochloric acid. 5 (c)Properties of carbon(IV)oxide gas(Questions) 1.Write the equation for the reaction for the school laboratory preparation of carbon (IV)oxide gas. Any carbonate reacted with dilute hydrochloric acid should be able to generate carbon (IV)oxide gas.
(b)School Laboratory preparation In the school laboratory carbon(IV)oxide can be prepared in the school laboratory from the reaction of marble chips(CaCO3)or sodium hydrogen carbonate(NaHCO3) with dilute hydrochloric acid. 5 (c)Properties of carbon(IV)oxide gas(Questions) 1.Write the equation for the reaction for the school laboratory preparation of carbon (IV)oxide gas. Any carbonate reacted with dilute hydrochloric acid should be able to generate carbon (IV)oxide gas. Chemical equations CaCO3(s) + 2HCl(aq) -> CaCO3 (aq) + H2O(l) + CO2 (g) ZnCO3(s) + 2HCl(aq) -> ZnCO3 (aq) + H2O(l) + CO2 (g) MgCO3(s) + 2HCl(aq) -> MgCO3 (aq) + H2O(l) + CO2 (g) CuCO3(s) + 2HCl(aq) -> CuCO3 (aq) + H2O(l) + CO2 (g) NaHCO3(s) + HCl(aq) -> Na2CO3 (aq) + H2O(l) + CO2 (g) KHCO3(s) + HCl(aq) -> K2CO3 (aq) + H2O(l) + CO2 (g) 2.What method of gas collection is used in preparation of Carbon(IV)oxide gas. Explain. Downward delivery /upward displacement of air/over mercury Carbon(IV)oxide gas is about 1½ times denser than air. 3.What is the purpose of : (a)water? To absorb the more volatile hydrogen chloride fumes produced during the vigorous reaction. (b)sodium hydrogen carbonate? To absorb the more volatile hydrogen chloride fumes produced during the vigorous reaction and by reacting with the acid to produce more carbon (IV)oxide gas . 6 Chemical equation NaHCO3(s) + HCl(aq) -> Na2CO3 (aq) + H2O(l) + CO2 (g) (c)concentrated sulphuric(VI)acid? To dry the gas/as a drying agent 4.Describe the smell of carbon(IV)oxide gas Colourless and odourless 5. Effect on lime water.
6 Chemical equation NaHCO3(s) + HCl(aq) -> Na2CO3 (aq) + H2O(l) + CO2 (g) (c)concentrated sulphuric(VI)acid? To dry the gas/as a drying agent 4.Describe the smell of carbon(IV)oxide gas Colourless and odourless 5. Effect on lime water. Experiment Bubbled carbon(IV)oxide gas into a test tube containing lime water for about three minutes Observation White precipitate is formed. White precipitate dissolved when excess carbon(IV)oxide gas is bubbled . Explanation Carbon(IV)oxide gas reacts with lime water(Ca(OH)2) to form an insoluble white precipitate of calcium carbonate. Calcium carbonate reacts with more Carbon(IV) oxide gas to form soluble Calcium hydrogen carbonate. Chemical equation Ca(OH)2(aq) + CO2 (g) -> CaCO3 (s) + H2O(l) CaCO3 (aq) + H2O(l) + CO2 (g) -> Ca(HCO3) 2 (aq) 6. Effects on burning Magnesium ribbon Experiment Lower a piece of burning magnesium ribbon into a gas jar containing carbon (IV)oxide gas. Observation The ribbon continues to burn with difficulty White ash/solid is formed. Black speck/solid/particles formed on the side of gas jar. Explanation Carbon(IV)oxide gas does not support combustion/burning.Magnesium burn to produce/release enough heat energy to decompose Carbon(IV) oxide gas to carbon and oxygen.Magnesium continues to burn in Oxygen forming white Magnesium Oxide solid/ash.Black speck/particle of carbon/charcoal residue forms on the sides of reaction flask. During the reaction Carbon(IV) oxide is reduced(Oxidizing agent)to carbon while Magnesium is Oxidized to Magnesium Oxide. Chemical equation 2Mg(s) + CO2 (g) -> C (s) + 2MgO(l)
7 7. Dry and wet litmus papers were separately put in a gas jar containing dry carbon (IV)oxide gas. State and explain the observations made.
Chemical equation 2Mg(s) + CO2 (g) -> C (s) + 2MgO(l)
7 7. Dry and wet litmus papers were separately put in a gas jar containing dry carbon (IV)oxide gas. State and explain the observations made. Observation Blue dry litmus paper remain blue Red dry litmus paper remain Red Blue wet/damp/moist litmus paper turn red Red wet/damp/moist litmus paper remain red Explanation Dry Carbon (IV) oxide gas is a molecular compound that does not dissociate/ionize to release H+ and thus has no effect on litmus papers. Wet/damp/moist litmus papers contains water that dissolves/react with dry carbon (IV) oxide gas to form the weak solution of carbonic (IV) acid(H2CO3). Carbonic (IV) acid dissociate/ionizes to a few /little free H+ and CO32-. The few H+ (aq) ions are responsible for turning blue litmus paper to faint red showing the gas is very weakly acidic. Chemical equation H2CO3(aq) -> 2H+ (aq) + CO32-(aq) 8. Explain why Carbon (IV)oxide cannot be prepared from the reaction of: (i) marble chips with dilute sulphuric(VI)acid. Explanation Reaction forms insoluble calcium sulphate(VI)that cover/coat unreacted marble chips stopping further reaction Chemical equation CaCO3(s) + H2SO4 (aq) -> CaSO4 (s) + H2O(l) + CO2 (g) PbCO3(s) + H2SO4 (aq) -> PbSO4 (s) + H2O(l) + CO2 (g) BaCO3(s) + H2SO4 (aq) -> BaSO4 (s) + H2O(l) + CO2 (g) (ii) Lead(II)carbonate with dilute Hydrochloric acid. Reaction forms insoluble Lead(II)Chloride that cover/coat unreacted Lead(II) carbonate stopping further reaction unless the reaction mixture is heated. Lead(II)Chloride is soluble in hot water. Chemical equation PbCO3(s) + 2HCl (aq) -> PbCl2 (s) + H2O(l) + CO2 (g) 9.
Reaction forms insoluble Lead(II)Chloride that cover/coat unreacted Lead(II) carbonate stopping further reaction unless the reaction mixture is heated. Lead(II)Chloride is soluble in hot water. Chemical equation PbCO3(s) + 2HCl (aq) -> PbCl2 (s) + H2O(l) + CO2 (g) 9. Describe the test for the presence of Carbon (IV)oxide. Using burning splint Lower a burning splint into a gas jar suspected to contain Carbon (IV)oxide gas.The burning splint is extinguished. Using Lime water. Bubble the gas suspected to be Carbon (IV)oxide gas.A white precipitate that dissolve in excess bubbling is formed. 8 Chemical equation Ca(OH)2(aq) + CO2 (g) -> CaCO3 (s) + H2O(l) CaCO3 (aq) + H2O(l) + CO2 (g) -> Ca(HCO3) 2 (aq) 10.State three main uses of Carbon (IV)oxide gas (i)In the Solvay process for the manufacture of soda ash/sodium carbonate (ii)In preservation of aerated drinks (iii)As fire extinguisher because it does not support combustion and is denser than air. (iv)In manufacture of Baking powder. (ii) Carbon(II)Oxide (CO) (a)Occurrence Carbon(II)oxide is found is found from incomplete combustion of fuels like petrol charcoal, liquefied Petroleum Gas/LPG. (b)School Laboratory preparation In the school laboratory carbon(II)oxide can be prepared from dehydration of methanoic acid/Formic acid(HCOOH) or Ethan-1,2-dioic acid/Oxalic acid(HOOCCOOH) using concentrated sulphuric(VI) acid. Heating is necessary.
(ii) Carbon(II)Oxide (CO) (a)Occurrence Carbon(II)oxide is found is found from incomplete combustion of fuels like petrol charcoal, liquefied Petroleum Gas/LPG. (b)School Laboratory preparation In the school laboratory carbon(II)oxide can be prepared from dehydration of methanoic acid/Formic acid(HCOOH) or Ethan-1,2-dioic acid/Oxalic acid(HOOCCOOH) using concentrated sulphuric(VI) acid. Heating is necessary. METHOD 1:Preparation of Carbon (IV)Oxide from dehydration of Oxalic/ethan-1,2-dioic acid METHOD 2:Preparation of Carbon (IV)Oxide from dehydration of Formic/Methanoic acid
9 (c)Properties of Carbon (II)Oxide(Questions) 1.Write the equation for the reaction for the preparation of carbon(II)oxide using; (i)Method 1; Chemical equation HOOCCOOH(s) –Conc.H2SO4--> CO(g) + CO2 (g) + H2O(l) H2C2O4(s) –Conc.H2SO4--> CO(g) + CO2 (g) + H2O(l) (ii)Method 2; Chemical equation HCOOH(s) –Conc.H2SO4--> CO(g) + H2O(l) H2CO2(s) –Conc.H2SO4--> CO(g) + H2O(l) 2.What method of gas collection is used during the preparation of carbon (II) oxide. Over water because the gas is insoluble in water. Downward delivery because the gas is 1 ½ times denser than air . 3.What is the purpose of : (i) Potassium hydroxide/sodium hydroxide in Method 1 To absorb/ remove carbon (II) oxide produced during the reaction. 2KOH (aq) + CO2 (g) -> K2CO3 (s) + H2O(l) 2NaOH (aq) + CO2 (g) -> Na2CO3 (s) + H2O(l) (ii) Concentrated sulphuric(VI)acid in Method 1 and 2.
Downward delivery because the gas is 1 ½ times denser than air . 3.What is the purpose of : (i) Potassium hydroxide/sodium hydroxide in Method 1 To absorb/ remove carbon (II) oxide produced during the reaction. 2KOH (aq) + CO2 (g) -> K2CO3 (s) + H2O(l) 2NaOH (aq) + CO2 (g) -> Na2CO3 (s) + H2O(l) (ii) Concentrated sulphuric(VI)acid in Method 1 and 2. Dehydrating agent –removes the element of water (Hydrogen and Oxygen in ratio 2:1) present in both methanoic and ethan-1,2-dioic acid. 10 4. Describe the smell of carbon(II)oxide. Colourless and odourless. 5. State and explain the observation made when carbon(IV)oxide is bubbled in lime water for a long time. No white precipitate is formed. 6. Dry and wet/moist/damp litmus papers were separately put in a gas jar containing dry carbon(IV)oxide gas. State and explain the observations made. Observation -blue dry litmus paper remains blue -red dry litmus paper remains red - wet/moist/damp blue litmus paper remains blue - wet/moist/damp red litmus paper remains red Explanation Carbon(II)oxide gas is a molecular compound that does not dissociate /ionize to release H+ ions and thus has no effect on litmus papers. Carbon(II)oxide gas is therefore a neutral gas. 7. Carbon (II)oxide gas was ignited at the end of a generator as below. (i)State the observations made in flame K. Gas burns with a blue flame (ii)Write the equation for the reaction taking place at flame K. 2CO(g) + O2 (g) -> 2CO2 (g) 8. Carbon(II)oxide is a reducing agent. Explain Experiment Pass carbon(II)oxide through glass tube containing copper (II)oxide. Ignite any excess poisonous carbon(II)oxide. 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.