JK-TK/Newdata huggingface dataset:
(b) Observations in lime water. A white precipitate is formed that dissolve to a colourless solution later. Lime water/Calcium hydroxide reacts with carbon(IV)0xide produced during the fermentation to form insoluble calcium carbonate and water. More carbon (IV)0xide produced during fermentation react with the insoluble calcium carbonate and water to form soluble calcium hydrogen carbonate. Ca(OH)2(aq) + CO2 (g) -> CaCO3(s) H2O(l) + CO2 (g) + CaCO3(s) -> Ca(HCO3) 2 (aq) (c)Effects on litmus paper Experiment Take the prepared sample and test with both blue and red litmus papers. Repeat the same with pure ethanol and methylated spirit. Sample Observation table Substance/alkanol Effect on litmus paper Prepared sample Blue litmus paper remain blue Red litmus paper remain red Absolute ethanol Blue litmus paper remain blue Red litmus paper remain red Methylated spirit Blue litmus paper remain blue Red litmus paper remain red Explanation Alkanols are neutral compounds/solution that have characteristic sweet smell and taste. They have no effect on both blue and red litmus papers. (d)Solubility in water. Experiment Place about 5cm3 of prepared sample into a clean test tube Add equal amount of distilled water. Repeat the same with pure ethanol and methylated spirit. Observation No layers formed between the two liquids. Explanation Ethanol is miscible in water.Both ethanol and water are polar compounds . 68 The solubility of alkanols decrease with increase in the alkyl chain/molecular mass. The alkyl group is insoluble in water while –OH functional group is soluble in water. As the molecular chain becomes longer ,the effect of the alkyl group increases as the effect of the functional group decreases. e)Melting/boiling point. Experiment Place pure ethanol in a long boiling tube .Determine its boiling point. Observation Pure ethanol has a boiling point of 78oC at sea level/one atmosphere pressure. Explanation The melting and boiling point of alkanols increase with increase in molecular chain/mass . This is because the intermolecular/van-der-waals forces of attraction between the molecules increase. More heat energy is thus required to weaken the longer chain during melting and break during boiling.
Explanation The melting and boiling point of alkanols increase with increase in molecular chain/mass . This is because the intermolecular/van-der-waals forces of attraction between the molecules increase. More heat energy is thus required to weaken the longer chain during melting and break during boiling. f)Density Density of alkanols increase with increase in the intermolecular/van-der-waals forces of attraction between the molecule, making it very close to each other. This reduces the volume occupied by the molecule and thus increase the their mass per unit volume (density). Summary table showing the trend in physical properties of alkanols Alkanol Melting point (oC) Boiling point (oC) Density gcm-3 Solubility in water Methanol -98 65 0.791 soluble Ethanol -117 78 0.789 soluble Propanol -103 97 0.803 soluble Butanol -89 117 0.810 Slightly soluble Pentanol -78 138 0.814 Slightly soluble Hexanol -52 157 0.815 Slightly soluble Heptanol -34 176 0.822 Slightly soluble Octanol -15 195 0.824 Slightly soluble Nonanol -7 212 0.827 Slightly soluble Decanol 6 228 0.827 Slightly soluble
69 g)Burning Experiment Place the prepared sample in a watch glass. Ignite. Repeat with pure ethanol and methylated spirit. Observation/Explanation Fermentation produce ethanol with a lot of water(about a ratio of 1:3)which prevent the alcohol from igniting. Pure ethanol and methylated spirit easily catch fire / highly flammable. They burn with an almost colourless non-sooty/non-smoky blue flame to form carbon(IV) oxide (in excess air/oxygen)or carbon(II) oxide (limited air) and water. Ethanol is thus a saturated compound like alkanes.
Pure ethanol and methylated spirit easily catch fire / highly flammable. They burn with an almost colourless non-sooty/non-smoky blue flame to form carbon(IV) oxide (in excess air/oxygen)or carbon(II) oxide (limited air) and water. Ethanol is thus a saturated compound like alkanes. Chemica equation C2 H5OH(l) + 3O2 (g) -> 3H2O(l) + 2CO2 (g) ( excess air) C2 H5OH(l) + 2O2 (g) -> 3H2O(l) + 2CO (g) ( limited air) 2CH3OH(l) + 3O2 (g) -> 4H2O(l) + 2CO2 (g) ( excess air) 2 CH3OH(l) + 2O2 (g) -> 4H2O(l) + 2CO (g) ( limited air) 2C3 H7OH(l) + 9O2 (g) -> 8H2O(l) + 6CO2 (g) ( excess air) C3 H7OH(l) + 3O2 (g) -> 4H2O(l) + 3CO (g) ( limited air) 2C4 H9OH(l) + 13O2 (g) -> 20H2O(l) + 8CO2 (g) ( excess air) C4 H9OH(l) + 3O2 (g) -> 4H2O(l) + 3CO (g) ( limited air) Due to its flammability, ethanol is used; (i) as a fuel in spirit lamps (ii) as gasohol when blended with gasoline (h)Formation of alkoxides Experiment Cut a very small piece of sodium. Put it in a beaker containing about 20cm3 of the prepared sample in a beaker. Test the products with litmus papers. Repeat with absolute ethanol and methylated spirit.
Put it in a beaker containing about 20cm3 of the prepared sample in a beaker. Test the products with litmus papers. Repeat with absolute ethanol and methylated spirit. Sample observations Substance/alkanol Effect of adding sodium Fermentation prepared sample (i)effervescence/fizzing/bubbles
70 (ii)colourless gas produced that extinguish burning splint with explosion/ “Pop” sound (iii)colourless solution formed (iv)blue litmus papers remain blue (v)red litmus papers turn blue Pure/absolute ethanol/methylated spirit (i)slow effervescence/fizzing/bubbles (ii)colourless gas slowly produced that extinguish burning splint with explosion/ “Pop” sound (iii)colourless solution formed (iv)blue litmus papers remain blue (v)red litmus papers turn blue Explanations Sodium/potassium reacts slowly with alkanols to form basic solution called alkoxides and producing hydrogen gas. If the alkanol has some water the metals react faster with the water to form soluble hydroxides/alkalis i.e.
Repeat with absolute ethanol and methylated spirit. Sample observations Substance/alkanol Effect of adding sodium Fermentation prepared sample (i)effervescence/fizzing/bubbles
70 (ii)colourless gas produced that extinguish burning splint with explosion/ “Pop” sound (iii)colourless solution formed (iv)blue litmus papers remain blue (v)red litmus papers turn blue Pure/absolute ethanol/methylated spirit (i)slow effervescence/fizzing/bubbles (ii)colourless gas slowly produced that extinguish burning splint with explosion/ “Pop” sound (iii)colourless solution formed (iv)blue litmus papers remain blue (v)red litmus papers turn blue Explanations Sodium/potassium reacts slowly with alkanols to form basic solution called alkoxides and producing hydrogen gas. If the alkanol has some water the metals react faster with the water to form soluble hydroxides/alkalis i.e. Sodium + Alkanol -> Sodium alkoxides + Hydrogen gas Potassium + Alkanol -> Potassium alkoxides + Hydrogen gas Sodium + Water -> Sodium hydroxides + Hydrogen gas Potassium + Water -> Potassium hydroxides + Hydrogen gas Examples 1.Sodium metal reacts with ethanol to form sodium ethoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2OH(l) + 2Na(s) -> 2CH3CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) 2.Potassium metal reacts with ethanol to form Potassium ethoxide Potassium metal reacts with water to form Potassium Hydroxide 2CH3CH2OH(l) + 2K(s) -> 2CH3CH2OK (aq) + H2 (s) 2H2O(l) + 2K(s) -> 2KOH (aq) + H2 (s) 3.Sodium metal reacts with propanol to form sodium propoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2OH(l) + 2Na(s) -> 2CH3CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s)
71 4.Potassium metal reacts with propanol to form Potassium propoxide Potassium metal reacts with water to form Potassium Hydroxide 2CH3CH2 CH2OH(l) + 2K(s) -> 2CH3CH2 CH2OK (aq) + H2 (s) 2H2O(l) + 2K(s) -> 2KOH (aq) + H2 (s) 5.Sodium metal reacts with butanol to form sodium butoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2 CH2OH(l) + 2Na(s) -> 2CH3CH2 CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) 6.Sodium metal reacts with pentanol to form sodium pentoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2 CH2 CH2OH(l)+2Na(s) -> 2CH3CH2 CH2 CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) (i)Formation of Esters/Esterification Experiment Place 2cm3 of ethanol in a boiling tube.
Sample observations Substance/alkanol Effect of adding sodium Fermentation prepared sample (i)effervescence/fizzing/bubbles
70 (ii)colourless gas produced that extinguish burning splint with explosion/ “Pop” sound (iii)colourless solution formed (iv)blue litmus papers remain blue (v)red litmus papers turn blue Pure/absolute ethanol/methylated spirit (i)slow effervescence/fizzing/bubbles (ii)colourless gas slowly produced that extinguish burning splint with explosion/ “Pop” sound (iii)colourless solution formed (iv)blue litmus papers remain blue (v)red litmus papers turn blue Explanations Sodium/potassium reacts slowly with alkanols to form basic solution called alkoxides and producing hydrogen gas. If the alkanol has some water the metals react faster with the water to form soluble hydroxides/alkalis i.e. Sodium + Alkanol -> Sodium alkoxides + Hydrogen gas Potassium + Alkanol -> Potassium alkoxides + Hydrogen gas Sodium + Water -> Sodium hydroxides + Hydrogen gas Potassium + Water -> Potassium hydroxides + Hydrogen gas Examples 1.Sodium metal reacts with ethanol to form sodium ethoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2OH(l) + 2Na(s) -> 2CH3CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) 2.Potassium metal reacts with ethanol to form Potassium ethoxide Potassium metal reacts with water to form Potassium Hydroxide 2CH3CH2OH(l) + 2K(s) -> 2CH3CH2OK (aq) + H2 (s) 2H2O(l) + 2K(s) -> 2KOH (aq) + H2 (s) 3.Sodium metal reacts with propanol to form sodium propoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2OH(l) + 2Na(s) -> 2CH3CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s)
71 4.Potassium metal reacts with propanol to form Potassium propoxide Potassium metal reacts with water to form Potassium Hydroxide 2CH3CH2 CH2OH(l) + 2K(s) -> 2CH3CH2 CH2OK (aq) + H2 (s) 2H2O(l) + 2K(s) -> 2KOH (aq) + H2 (s) 5.Sodium metal reacts with butanol to form sodium butoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2 CH2OH(l) + 2Na(s) -> 2CH3CH2 CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) 6.Sodium metal reacts with pentanol to form sodium pentoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2 CH2 CH2OH(l)+2Na(s) -> 2CH3CH2 CH2 CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) (i)Formation of Esters/Esterification Experiment Place 2cm3 of ethanol in a boiling tube. Add equal amount of ethanoic acid.To the mixture add carefully 2drops of concentrated sulphuric(VI)acid.
If the alkanol has some water the metals react faster with the water to form soluble hydroxides/alkalis i.e. Sodium + Alkanol -> Sodium alkoxides + Hydrogen gas Potassium + Alkanol -> Potassium alkoxides + Hydrogen gas Sodium + Water -> Sodium hydroxides + Hydrogen gas Potassium + Water -> Potassium hydroxides + Hydrogen gas Examples 1.Sodium metal reacts with ethanol to form sodium ethoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2OH(l) + 2Na(s) -> 2CH3CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) 2.Potassium metal reacts with ethanol to form Potassium ethoxide Potassium metal reacts with water to form Potassium Hydroxide 2CH3CH2OH(l) + 2K(s) -> 2CH3CH2OK (aq) + H2 (s) 2H2O(l) + 2K(s) -> 2KOH (aq) + H2 (s) 3.Sodium metal reacts with propanol to form sodium propoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2OH(l) + 2Na(s) -> 2CH3CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s)
71 4.Potassium metal reacts with propanol to form Potassium propoxide Potassium metal reacts with water to form Potassium Hydroxide 2CH3CH2 CH2OH(l) + 2K(s) -> 2CH3CH2 CH2OK (aq) + H2 (s) 2H2O(l) + 2K(s) -> 2KOH (aq) + H2 (s) 5.Sodium metal reacts with butanol to form sodium butoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2 CH2OH(l) + 2Na(s) -> 2CH3CH2 CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) 6.Sodium metal reacts with pentanol to form sodium pentoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2 CH2 CH2OH(l)+2Na(s) -> 2CH3CH2 CH2 CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) (i)Formation of Esters/Esterification Experiment Place 2cm3 of ethanol in a boiling tube. Add equal amount of ethanoic acid.To the mixture add carefully 2drops of concentrated sulphuric(VI)acid. Warm/Heat gently.
Sodium + Alkanol -> Sodium alkoxides + Hydrogen gas Potassium + Alkanol -> Potassium alkoxides + Hydrogen gas Sodium + Water -> Sodium hydroxides + Hydrogen gas Potassium + Water -> Potassium hydroxides + Hydrogen gas Examples 1.Sodium metal reacts with ethanol to form sodium ethoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2OH(l) + 2Na(s) -> 2CH3CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) 2.Potassium metal reacts with ethanol to form Potassium ethoxide Potassium metal reacts with water to form Potassium Hydroxide 2CH3CH2OH(l) + 2K(s) -> 2CH3CH2OK (aq) + H2 (s) 2H2O(l) + 2K(s) -> 2KOH (aq) + H2 (s) 3.Sodium metal reacts with propanol to form sodium propoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2OH(l) + 2Na(s) -> 2CH3CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s)
71 4.Potassium metal reacts with propanol to form Potassium propoxide Potassium metal reacts with water to form Potassium Hydroxide 2CH3CH2 CH2OH(l) + 2K(s) -> 2CH3CH2 CH2OK (aq) + H2 (s) 2H2O(l) + 2K(s) -> 2KOH (aq) + H2 (s) 5.Sodium metal reacts with butanol to form sodium butoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2 CH2OH(l) + 2Na(s) -> 2CH3CH2 CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) 6.Sodium metal reacts with pentanol to form sodium pentoxide Sodium metal reacts with water to form sodium Hydroxide 2CH3CH2 CH2 CH2 CH2OH(l)+2Na(s) -> 2CH3CH2 CH2 CH2 CH2ONa (aq) + H2 (s) 2H2O(l) + 2Na(s) -> 2NaOH (aq) + H2 (s) (i)Formation of Esters/Esterification Experiment Place 2cm3 of ethanol in a boiling tube. Add equal amount of ethanoic acid.To the mixture add carefully 2drops of concentrated sulphuric(VI)acid. Warm/Heat gently. Pour the mixture into a beaker containing about 50cm3 of cold water.
Add equal amount of ethanoic acid.To the mixture add carefully 2drops of concentrated sulphuric(VI)acid. Warm/Heat gently. Pour the mixture into a beaker containing about 50cm3 of cold water. Smell the products. Repeat with methanol Sample observations Substance/alkanol Effect on adding equal amount of ethanol/concentrated sulphuric(VI)acid Absolute ethanol Sweet fruity smell Methanol Sweet fruity smell Explanation Alkanols react with alkanoic acids to form a group of homologous series of sweet smelling compounds called esters and water. This reaction is catalyzed by concentrated sulphuric(VI)acid in the laboratory. Alkanol + Alkanoic acid –Conc. H2SO4-> Ester + water Naturally esterification is catalyzed by sunlight. Each ester has a characteristic smell derived from the many possible combinations of alkanols and alkanoic acids that
72 create a variety of known natural(mostly in fruits) and synthetic(mostly in juices) esters . Esters derive their names from the alkanol first then alkanoic acids. The alkanol “becomes” an alkyl group and the alkanoic acid “becomes” alkanoate hence alkylalkanoate. e.g. Ethanol + Ethanoic acid -> Ethylethanoate + Water Ethanol + Propanoic acid -> Ethylpropanoate + Water Ethanol + Methanoic acid -> Ethylmethanoate + Water Ethanol + butanoic acid -> Ethylbutanoate + Water Propanol + Ethanoic acid -> Propylethanoate + Water Methanol + Ethanoic acid -> Methyethanoate + Water Methanol + Decanoic acid -> Methyldecanoate + Water Decanol + Methanoic acid -> Decylmethanoate + Water During the formation of the ester, the “O” joining the alkanol and alkanoic acid comes from the alkanol. R1 -COOH + R2 –OH -> R1 -COO –R2 + H2O e.g. 1. Ethanol reacts with ethanoic acid to form the ester ethyl ethanoate and water. Ethanol + Ethanoic acid --Conc.
1. Ethanol reacts with ethanoic acid to form the ester ethyl ethanoate and water. Ethanol + Ethanoic acid --Conc. H2SO4 -->Ethylethanoate + Water C2H5OH (l) + CH3COOH(l) --Conc. H2SO4 --> CH3COO C2H5(aq) +H2O(l) CH3CH2OH (l)+ CH3COOH(l) --Conc. H2SO4 --> CH3COOCH2CH3(aq) +H2O(l) 2. Ethanol reacts with propanoic acid to form the ester ethylpropanoate and water. Ethanol + Propanoic acid --Conc. H2SO4 -->Ethylethanoate + Water C2H5OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 -->CH3CH2COO C2H5(aq) +H2O(l) CH3CH2OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 --> CH3 CH2COOCH2CH3(aq) +H2O(l) 3. Methanol reacts with ethanoic acid to form the ester methyl ethanoate and water. Methanol + Ethanoic acid --Conc. H2SO4 -->Methylethanoate + Water CH3OH (l) + CH3COOH(l) --Conc. H2SO4 --> CH3COO CH3(aq) +H2O(l) 4. Methanol reacts with propanoic acid to form the ester methyl propanoate and water. Methanol + propanoic acid --Conc. H2SO4 -->Methylpropanoate + Water CH3OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 --> CH3 CH2COO CH3(aq) +H2O(l) 5. Propanol reacts with propanoic acid to form the ester propylpropanoate and water. 73 Propanol + Propanoic acid --Conc.
H2SO4 --> CH3 CH2COO CH3(aq) +H2O(l) 5. Propanol reacts with propanoic acid to form the ester propylpropanoate and water. 73 Propanol + Propanoic acid --Conc. H2SO4 -->Ethylethanoate + Water C3H7OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 -->CH3CH2COO C3H7(aq) +H2O(l) CH3CH2 CH2OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 --> CH3 CH2COOCH2 CH2CH3(aq) +H2O(l) (j)Oxidation Experiment Place 5cm3 of absolute ethanol in a test tube.Add three drops of acidified potassium manganate(VII).Shake thoroughly for one minute/warm.Test the solution mixture using pH paper. Repeat by adding acidified potassium dichromate(VII). Sample observation table Substance/alkanol Adding acidified KMnO4/K2Cr2O7 pH of resulting solution/mixture Nature of resulting solution/mixture Pure ethanol (i)Purple colour of KMnO4decolorized (ii) Orange colour of K2Cr2O7turns green. pH= 4/5/6 pH = 4/5/6 Weakly acidic Weakly acidic Explanation Both acidified KMnO4 and K2Cr2O7 are oxidizing agents(add oxygen to other compounds.
Repeat by adding acidified potassium dichromate(VII). Sample observation table Substance/alkanol Adding acidified KMnO4/K2Cr2O7 pH of resulting solution/mixture Nature of resulting solution/mixture Pure ethanol (i)Purple colour of KMnO4decolorized (ii) Orange colour of K2Cr2O7turns green. pH= 4/5/6 pH = 4/5/6 Weakly acidic Weakly acidic Explanation Both acidified KMnO4 and K2Cr2O7 are oxidizing agents(add oxygen to other compounds. They oxidize alkanols to a group of homologous series called alkanals then further oxidize them to alkanoic acids.The oxidizing agents are themselves reduced hence changing their colour: (i) Purple KMnO4 is reduced to colourless Mn2+ (ii)Orange K2Cr2O7is reduced to green Cr3+ The pH of alkanoic acids show they have few H+ because they are weak acids i.e Alkanol + [O] -> Alkanal + [O] -> alkanoic acid NB The [O] comes from the oxidizing agents acidified KMnO4 or K2Cr2O7 Examples 1.When ethanol is warmed with three drops of acidified KMnO4 there is decolorization of KMnO4 Ethanol + [O] -> Ethanal + [O] -> Ethanoic acid CH3CH2OH + [O] -> CH3CH2O + [O] -> CH3COOH 2.When methanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green. 74 methanol + [O] -> methanal + [O] -> methanoic acid CH3OH + [O] -> CH3O + [O] -> HCOOH 3.When propanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green.
pH= 4/5/6 pH = 4/5/6 Weakly acidic Weakly acidic Explanation Both acidified KMnO4 and K2Cr2O7 are oxidizing agents(add oxygen to other compounds. They oxidize alkanols to a group of homologous series called alkanals then further oxidize them to alkanoic acids.The oxidizing agents are themselves reduced hence changing their colour: (i) Purple KMnO4 is reduced to colourless Mn2+ (ii)Orange K2Cr2O7is reduced to green Cr3+ The pH of alkanoic acids show they have few H+ because they are weak acids i.e Alkanol + [O] -> Alkanal + [O] -> alkanoic acid NB The [O] comes from the oxidizing agents acidified KMnO4 or K2Cr2O7 Examples 1.When ethanol is warmed with three drops of acidified KMnO4 there is decolorization of KMnO4 Ethanol + [O] -> Ethanal + [O] -> Ethanoic acid CH3CH2OH + [O] -> CH3CH2O + [O] -> CH3COOH 2.When methanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green. 74 methanol + [O] -> methanal + [O] -> methanoic acid CH3OH + [O] -> CH3O + [O] -> HCOOH 3.When propanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green. Propanol + [O] -> Propanal + [O] -> Propanoic acid CH3CH2 CH2OH + [O] -> CH3CH2 CH2O + [O] -> CH3 CH2COOH 4.When butanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green.
They oxidize alkanols to a group of homologous series called alkanals then further oxidize them to alkanoic acids.The oxidizing agents are themselves reduced hence changing their colour: (i) Purple KMnO4 is reduced to colourless Mn2+ (ii)Orange K2Cr2O7is reduced to green Cr3+ The pH of alkanoic acids show they have few H+ because they are weak acids i.e Alkanol + [O] -> Alkanal + [O] -> alkanoic acid NB The [O] comes from the oxidizing agents acidified KMnO4 or K2Cr2O7 Examples 1.When ethanol is warmed with three drops of acidified KMnO4 there is decolorization of KMnO4 Ethanol + [O] -> Ethanal + [O] -> Ethanoic acid CH3CH2OH + [O] -> CH3CH2O + [O] -> CH3COOH 2.When methanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green. 74 methanol + [O] -> methanal + [O] -> methanoic acid CH3OH + [O] -> CH3O + [O] -> HCOOH 3.When propanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green. Propanol + [O] -> Propanal + [O] -> Propanoic acid CH3CH2 CH2OH + [O] -> CH3CH2 CH2O + [O] -> CH3 CH2COOH 4.When butanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green. Butanol + [O] -> Butanal + [O] -> Butanoic acid CH3CH2 CH2 CH2OH + [O] ->CH3CH2 CH2CH2O +[O] -> CH3 CH2COOH Air slowly oxidizes ethanol to dilute ethanoic acid commonly called vinegar. If beer is not tightly corked, a lot of carbon(IV)oxide escapes and there is slow oxidation of the beer making it “flat”.
Propanol + [O] -> Propanal + [O] -> Propanoic acid CH3CH2 CH2OH + [O] -> CH3CH2 CH2O + [O] -> CH3 CH2COOH 4.When butanol is warmed with three drops of acidified K2Cr2O7 ,the orange colour of acidified K2Cr2O7 changes to green. Butanol + [O] -> Butanal + [O] -> Butanoic acid CH3CH2 CH2 CH2OH + [O] ->CH3CH2 CH2CH2O +[O] -> CH3 CH2COOH Air slowly oxidizes ethanol to dilute ethanoic acid commonly called vinegar. If beer is not tightly corked, a lot of carbon(IV)oxide escapes and there is slow oxidation of the beer making it “flat”. (k)Hydrolysis /Hydration and Dehydration I. Hydrolysis/Hydration is the reaction of a compound/substance with water. Alkenes react with water vapour/steam at high temperatures and high pressures in presence of phosphoric acid catalyst to form alkanols.i.e. Alkenes + Water - H3PO4 catalyst-> Alkanol Examples (i)Ethene is mixed with steam over a phosphoric acid catalyst at 300oC temperature and 60 atmosphere pressure to form ethanol Ethene + water ---60 atm/300oC/ H3PO4 --> Ethanol H2C =CH2 (g) + H2O(l) --60 atm/300oC/ H3PO4 --> CH3 CH2OH(l) This is the main method of producing large quantities of ethanol instead of fermentation (ii) Propene + water ---60 atm/300oC/ H3PO4 --> Propanol CH3C =CH2 (g) + H2O(l) --60 atm/300oC/ H3PO4 --> CH3 CH2 CH2OH(l) (iii) Butene + water ---60 atm/300oC/ H3PO4 --> Butanol CH3 CH2 C=CH2 (g) + H2O(l) --60 atm/300oC/ H3PO4 --> CH3 CH2 CH2 CH2OH(l) II.