- What is a homologous series of compounds? List any two characteristics of a homologous series.
- What would be observed on adding a 5% alkaline potassium permanganate solution drop by drop to some warm ethanol in a test tube?
- Write the name of the compound formed during the chemical reaction.
- How would you distinguish experimentally between an alcohol and a carboxylic acid on the basis of a chemical property?
(a) A group of organic compounds that can be represented by the same general formula with the same functional group and which show more or less similar trends in their properties is known as homologous series.
Example: The homologous series of straight-chain alkanes can be represented by the general formula CnH 2n+2.
Two characteristics of a homologous series are:
- Each member of the series can be represented by a general formula.
- All the members of the series can be prepared by the same general methods.
(b) (i) On adding 5% alkaline potassium permanganate solution drop by drop to some warm ethanol, we would observe that the purple color of potassium permanganate starts disappearing.
(ii) The product formed by this process is ethanoic acid that can turn blue litmus red.
(c) Experimentally, we can distinguish between alcohol and carboxylic acid by conducting a litmus test.
Step 1: Take two test tubes and pour about 2 ml of carboxylic acid in one, and 2 ml of alcohol in the other.
Step 2: Add one drop of blue litmus solution in each of the test tubes.
The solution which shows no effect is alcohol. The solution that turns the blue litmus red is carboxylic acid.
Related Articles
- (a) What would be observed on adding a 5% alkaline potassium permanganate solution drop by drop to some warm ethanol in a test-tube? Write the name of the compound formed during the chemical reaction. Also write chemical equation of the reaction which takes place.(b) How would you distinguish experimentally between an alcohol and a carboxylic acid on the basis of a chemical property?
- What happens when 5% alkaline potassium permanganate solution is added drop by drop to warm propyl alcohol (propanol) taken in a test tube? Explain with the help of a chemical equation.
- How would you distinguish experimentally between an alcohol and a carboxylic acid?
- 3 mL of ethanol is taken in a test tube and warmed gently in a water bath. A 5% solution of alkaline potassium permanganate is added first drop by drop to this solution, then in excess.(I) How is 5% solution of KMn04 prepared?(ii) State the role of alkaline potassium permanganate in this reaction. What happens on adding it in excess?(iii) Write chemical equation of this reaction.
- A compound X is formed by the reaction of a carboxylic acid C2H4O2 and an alcohol in the presence of a few drops of H2SO4. The alcohol on oxidation with alkaline KMnO4 followed by acidification gives the same carboxylic acid as used in this reaction. Give the names and structures of (a) carboxylic acid, (b) alcohol and (c) the compound X. Also, write the reaction.
- (a) How is ethanoic acid obtained from ethanol? Write down the chemical equation of the reaction involved. (b) How would you distinguish between ethanol and ethanoic acid by chemical test? (c) Explain the formation of scum when hard water is treated with soap.
- What is a homologous series of carbon compounds? Give an example and list its three characteristics.
- (a) What is homologous series? Explain with an example.(b) State two characteristics of a homologous series. (c) The molecular formula of an organic compound is C18H36. Name its homologous series. (d) Select the hydrocarbons which belong to the same homologous series. Give the name of each series. CH4, C2H2 ,C3H4 ,C2H6 ,C4H10, C3H4, C3H6 . (e) What is meant by 'heteroatom'? Give examples. Write the names and formulae of two organic compounds containing different heteroatoms.
- What is a homologous series of carbon compounds?
- (a) Give one example of a chemical reaction.(b) State two characteristics of the chemical reaction which takes place when dilute sulphuric acid is poured over zinc granules. (c) Give two characteristics of the chemical reaction which occurs on adding potassium iodide solution to lead nitrate solution.
- (a) Write the name and formula of an organic compound containing a ketone functional group.(b) Write the names and formulae for the first three members of the homologous series of chloroalkanes. (c) How would you name the following compound? CH3-CH2-Br
- When potassium iodide solution is added to a solution of lead (II) nitrate in a test tube, a precipitate is formed.(a) What is the colour of this precipitate? Name the compound precipitated.(b) Write the balanced chemical equation for this reaction.(c) List two types of reactions in which this reaction can be placed.
- On adding dilute hydrochloric acid to copper oxide powder, the solution formed is blue-green.(a) Predict the new compound formed which imparts a blue-green colour to solution.(b) Write a balanced chemical equation of the reaction which takes place.(c) On the basis of the above reaction, what can you say about the nature of copper oxide?
- (a) Define a homologous series. Give the name and structural formula of one homologue of the following: CH3OH.(b) Write the molecular formula of the third member of the homologous series of carbon compounds with general formula CnH2n+ 1OH. (c) Name any two fossil fuels.
- Lead nitrate solution is added to a test tube containing potassium iodide solution.(a) Write the name and colour of the compound precipitated.(b) Write the balanced chemical equation for the reaction involved.(c) Name the type of this reaction justifying your answer.
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