ORGANIC REACTIONS BY EXPERIMENTS with answersNAME........................................................................C...
2) Dehydration of ethanol   a) What is the name of this reaction?      ......................................................
3) Oxidation of ethanol      a) By refer to diagram (a) What is the function of acidified potassium dichromate (VI)       ...
j) How do you confirm that the products is ethanoic acid?             ………………………………………………………………………………………..4) Preparation of...
.............................................................................................................................
b) C 2 H 5 OH + 2[O ] → CH 3 COOH + H 2 Oc) It requires long heating, so avoid the mixture from drying out .( organic reac...
h) i) to remove acid, shake with calcium carbonateii) to remove water , use drying agent such as anhydrous calcium chlorid...
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Organic reactions by experiments with answers 1

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Organic reactions by experiments with answers 1

  1. 1. ORGANIC REACTIONS BY EXPERIMENTS with answersNAME........................................................................CLASS..............TEACHER..............................1.Fermentation of glucose a)a)In diagram (a) what is the function of i) Yeast ..................................................................................................... ii) Lime water ............................................................................................. b) How long do you leave the mixture of glucose and yeast to react? ........................................................................................................................................... c) Explain why the other end of the test tube in diagram (a) must be dipped the lime water at all the times? ........................................................................................................................................... d) Suggest an optimum temperature to carry out the fermentation of glucose .......................................................................................................................................... e) Write chemical equation for fermentation of glucose ........................................................................................................................................... f) What is the products formed at the end of fermentation process? ........................................................................................................................................... g) What is the purpose of carrying out distillation process of ethanol in diagram (b)? ........................................................................................................................................... h) At what temperature do you collect the liquid during distillation process? ........................................................................................................................................... i) State 2 physical properties of the distillate formed ........................................................................................................................................... j) Suggest 2 method to confirm that the product formed is ethanol. ..........................................................................................................................................
  2. 2. 2) Dehydration of ethanol a) What is the name of this reaction? ........................................................................................................................................ b) What is the function of porcelain chip? ........................................................................................................................................ c) Why do you need to soaked ethanol with glass wool? Can glass wool be replaced with cotton wool? ........................................................................................................................................ d) Why do you need to heat the porcelain chips first before you can heat ethanol? ......................................................................................................................................... e) Name another substance that can replace porcelain chips. ........................................................................................................................................ f) Write chemical equation for the reaction that occur in the boiling tube .......................................................................................................................................... g) How do you test the presence of ethane gas? ......................................................................................................................................... h) Draw structural formula of ethene and state its homologous series i) If ethanol is replaced by propanol, name the gas that is produced ...........................................................................................................................................
  3. 3. 3) Oxidation of ethanol a) By refer to diagram (a) What is the function of acidified potassium dichromate (VI) solution? ............................................................................................................................. b) Write chemical equation for the reaction to produce ethanoic acid ............................................................................................................................ c) Why is the reflux method necessary for this experiment? ............................................................................................................................ d) Why does the flow of water in that direction? What if the flow is reversed ? ........................................................................................................................... ............................................................................................................................ e) State one observation from this experiment. .............................................................................................................................. f) Write chemical equation for the reaction to produce ethanoic acid. ............................................................................................................................... g) By refer to diagram (b), why does the distillation method necessary to obtain the product formed? ................................................................................................................................ h) At what temperature do you distil the ethanoic acid? .................................................................................................................................. i) Write 2 physical properties of the distillate formed ..................................................................................................................................
  4. 4. j) How do you confirm that the products is ethanoic acid? ………………………………………………………………………………………..4) Preparation of ester Reflux method a) What is the function of concentrated sulphuric acid? ............................................................................................................................................... b) Name the ester formed ............................................................................................................................................. c) Write chemical equation for the reaction to produce the ester in this experiment ............................................................................................................................................ d) Why is the reflux method necessary for this experiment? ............................................................................................................................................. Distillation method e) After doing the reflux method, the mixture of products formed is distilled through distillation method. Why does the distillation method necessary to obtain the product formed? ............................................................................................................................................ ............................................................................................................................................ f) At what temperature do you distil the ester formed? ............................................................................................................................................ g) State 3 observations from the experiment .......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... h) The ester formed still contains some water and acid. Describe briefly how you would purify the ester
  5. 5. ........................................................................................................................................ ....................................................................................................................................... ANSWERS:1)a) i) reacts with glucose to form ethanol. ii) to detect the presence of carbon dioxide b) 2-3 days c) To prevent air from entering the mixture, because yeast undergoes anaerobic respiration d) 25 -30 oC ( room temperature) e) C6H12O6  2C2H5OH + 2CO2 f) ethanol and carbon dioxide g) to produce pure ethanol from the mixture of glucose and yeast h) boiling point of ethanol that is 78 oC i) has low mp and bp, completely miscible in water, colorless liquid, sharp smell, volatile j) warm the liquid with acidified K2Cr2O7, color change from orange to green2) a) Dehydration b) As a catalyst and drying agent c) To avoid ethanol from flowing out. Cannot use cotton wool because it burns easily d) because the ethanol is very volatile, so evaporate easily e) Aluminium oxide or alumina, OR concentrated sulphuric acid f) C2H5OH  C2H4 + H2O g) Bubble the gas into bromine water brown bromine change to colourless h) alkene propene, C3H6 3) a) to oxidize ethanol to ethanoic acid
  6. 6. b) C 2 H 5 OH + 2[O ] → CH 3 COOH + H 2 Oc) It requires long heating, so avoid the mixture from drying out .( organic reaction takes a long time to complete)d) i) to make sure that the condenser is filled up ii) water going up will absorbs heat, so water is cooler If the flow is reversed, the condenser is not filled up and the water is not so coole) Acidified potassium dichromate change orange to greenf) C 2 H 5 OH + 2[O] → CH 3COOH + H 2 Og) To obtain pure ethanoic acid from mixture of ethanol and acidified potassiumdichromateh) boiling point of ethanoic acid is 118 o Ci) colourless liquid, sharp smell, smell like vinegar (product), soluble in waterj) i) add calcium carbonate to acidbubbles of gas that turns lime water chalkyii) Add magnesium ribbon to acidbubbles of gas that gives a ‘pop’ sound to burning wooden splinter4) a) Act as a catalyst for this reaction, a drying agentb) ethylethanoatec)CH 3COOH + C2 H 5OH → CH 3COOC2 H 5 + H 2Oethanoic acid ethanol ethylethanoated) to prevent the mixture from drying out, and to prevent loss of the producte) To obtain pure ethylethanoate from the mixture of ethanol and ethanoic acidf) boiling point of ethylethanoate is 77-80 o Cg) sweet smelling liquid is formed, colourless liquid, floats on water.
  7. 7. h) i) to remove acid, shake with calcium carbonateii) to remove water , use drying agent such as anhydrous calcium chlorideend.. tq

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