Organic Chemistry 1 Questions and Answers - Chemistry Form 3 Topical Revision

Share via Whatsapp
Download PDF for future reference Get on Whatsapp for 50/-

Questions

  1. Use the flow chart below to answer the questions that follow:

    flowchartq1orgchem
    1. What observation would be made in process K?
    2. Name another conditions necessary for process J to take place
    3. Give the name of substance V
  2. But-z-ene undergoes hydrogenation according to the equation given below
    CH3CH = CHCH3 (g) + H2(g) → CH3CH2CH2CH3(g)
    1. Name the product formed when but-z-ene reacts with hydrogen gas
    2. State one industrial use of hydrogenation
  3. Write the structures of the following compounds:-
    1. But-2-yne
    2. 2,2-dimethylpropane
  4.  
    1. What is meant by Isomerism?
    2. Draw and name two Isomers of butane.
  5. Study the information in the table below and answer the questions that follow:
     Ion  No. of protons  No. of electrons
     P3−  7  10
     Q+  19  18
     R2+  12  10

    1. Write the electron arrangement of element P.
    2. Give the group and period to which elements Q and R respectively.
      Q ……………………………………………………
      R ……………………………………………………
  6. Compound W reacted with chlorine to form compound X only. The structural formula of X is shown below:
    compound X
    1. Give the structural formula and name of compound W
    2. Name compound X ……………………………………………………………………
  7. In petrol chemical industries, long chain alkanes are broken down in to simpler substances in a process called cracking
    1. Why is cracking necessary?
    2. State the two conditions required in cracking
    3. Draw the structure of 1-chloro-2, 2-dimethylpropane
  8. In a reaction an alcohol K was converted to hex-1-ene
    Name reagent and condition necessary for the reaction above to occur
  9.  
    1. Give the IUPAC systematic names of compounds Q and R
      Q: CH2CHClCHClCH2CH3
      R: CH3CHClCH2ClCH3
    2. The organic compounds Q and R in (a) above, are formed when one mole of hydrocarbon b reacts with two moles of hydrogen chloride gas;
      1. Structural formula of N
      2. The IUPAC systematic name of N
  10. Distinguish between the isotopes and isomers
  11. Polymerisation of ethene takes place as shown in the equation below
    polymerisation of ethene
    Name the type of polymerisation undergone by ethene in the reaction above
  12. State Gay Lussac’s law
  13. 10cm3 of methane (CH4) gas is exploded with 150cm3 of air containing 20% oxygen and 80% nitrogen. The products were allowed to cool to room temperature. What will be the total volume of the gases at the end of the reaction?
  14. Give the open structures of:-
    1. 3-chlorohex-1-yne
    2. CH3OH
  15. A fixed mass of gas occupies 105cm3 at -14ºC and 650mmHg pressure. At what temperature in degrees Celsius will it have a volume of 15cm3 if the pressure is adjusted to 690mmHg pressure?
  16. Write an equation for the reaction that takes place between ethene and concentrated Sulphuric (VI) acid
  17. Petroleum (crude oil) is a mixture of several compounds which are separated in a Changamwe refinery by means of apparatus as shown below:
    refinery of crude oil
    1.  
      1. What is the name of the apparatus above
      2. What is the name of the process which is used in separation of crude oil
      3. What physical property of compounds in the mixture does the separation depend
      4. Use the letter A to G to describe where the following could be formed:.
        1. The fraction that represents gases
        2. The fraction that represents the largest molecules
        3. The fraction that represents liquids with the lowest boiling points
    2. State the use of product produce at
      G………………………………………………………………………………………
      C……………………………………………………………………………………….
    3. Draw apparatus for the separation of the product produce at D and water
  18. Study the flow chart below and answer the questions that follow:
    flowchartq18orgchem
    1. Give the name of the substance CH ≡ CH …………………………………………
    2. To which group of hydrocarbons does the substance in (i) above belong?
    3. Give two reagents that can be used to prepare the substance named in (i) above
    4. State two physical properties of the substances in (i) above
    5. Give the names to the process in step I and 2
    6. Write an equation to show how substance A is formed
    7. Identify substance B ……………………………………………………
  19. The diagram below represents a large-scale fractional distillation plant used to separate the components A, B, C and D in a mixture
    fractional distillaton plant
    The components have the following average relative molecular masses not necessarily in that order; 282, 184, 44 and 128.
    1. What is the physical state of B at the position marked Q?
    2. Which component has an average relative molecular mass of 128? Explain
    3. State with a reason whether C is pure or impure
    4. Explain how the mixture is separated into its components
    5. Name two naturally occurring mixtures that are separated using this process
  20.  
    1. The table below gives information about the major constituents of crude oil. Study it and answer the questions that follow:
       Constituent  Boiling point oC
       Gases  Below 40
       Petrol  40 -175
       Kerosene  175 - 250
       Diesel  250 - 350
       Lubricating oil  350 - 400
       Bitumen  Above 400

      1. Which of the constituents of crude has molecules with the highest number of carbon atoms? Explain
      2. Name the process you would use to separate a mixture of petrol and diesel and explain how the separation takes place
      3. Explain why the constituents of crude oil do not have a sharp boiling point
      4. Name the gas that is likely to be a constituent of crude oil and write its formula
    2.  
      1. What condition could cause a poisonous gas to be formed when kerosene is burnt. Explain
      2. Give one use of bitumen
  21.  
    1. The set-up below was used to prepare ethyne gas
      preparation of ethyne gas
      1. Identify solid E
      2. Complete the diagram to show how the gas can be collected
      3. Write an equation to show how the gas is formed
      4. Complete the equation below: 
        C2H2 + 2I2 →
      5. What is the role of sand in the experiment?
    2.  
      1. Explain the meaning of esterification
      2. Complete the equation below :
        CH3COOCH3 + H2O →
      3. What type of reaction is occurring above
    3. Given the reaction:
                 solid F
      C8H18    →     N + C2H4
      1. Identify substance:
        F………………………………… N………………………………
      2. Name the process represented above?
    4. Give one use of substance N
  22.  
    1.  
      flowchartq22orgchem
      1. Name another source of hydrogen apart from electrolysis of water
      2. What conditions are necessary for step III to occur?
      3. Write the equation for the formation of colourless gas Q
      4. Give one use of nitric (V) acid
    2. State and explain the observations that would be made if a sample of copper metal is heated with concentrated nitric (V) acid
  23.  
    1. Give the systematic names of the following compounds:-

      1. 2 bromo propene
        ..........................................................................
      2. CH3CH2CH2C ≡ CH .................................................................
    2. State the observations made when butan-1-ol reacts with:-
      1. Acidified potassium dichromate (VI) solution
      2. Potassium metal
    3. Ethanol obtained from glucose can be converted to ethene as shown below:-
                   Step I                Step II
      C6H12O6   →    C2H5OH    →   CH2 = CH2
      Name and describe the processes that take place in steps I and II
    4. Compounds A and B have the same molecular formula C3H6O2. Compound A librates Carbon (IV) Oxide on addition of aqueous sodium carbonate while compound B does not. Compound B has a sweet smell. Draw the possible structures of:-
      1. Compound A
      2. Compound B
    5. Give two ways how the disposal of polymers such as polychloroethene by burning pollutes the environment
  24.  
    1. Name the following compounds (CH3)3CCH2CH2CH3
      Use the flow chart below to answer the questions that follow:-
      flowchartq24aorgchem
    2.  
      1. Name the following :-
        1. Gas S ……………………………………………………………….…….
        2. Gas P …………………………………………………………………
        3. J ……………………………………………………………………….
      2. Name the processes involved in the following steps:
        1. Step I …………………………………………………………………………..
        2. Step II …………………………………………………………………………….
        3. Step III …………………………………………………………………………….
      3. Write a chemical equation for the complete combustion of substance M
      4. Name the condition and reagent in step III
        Condition ……………………………………………………………………………………
        Reagent …………………………………………………………………………………….
      5. Calculate the mass of salt R that would be formed by using 21.9 tonnes of N when it reacts with excess sodium hydroxide ( C= 12.0 H= 1.0 Na = 23)
      6.  
        1. Draw the structure of polymer K
        2. State one use of the above polymer
          ………………………………………………………………………………………………….
    3.  
      1. Name the class to which the following cleansing agents belong:-
        1. R – COONa+ ……………………………………………………

        2. soapless detergent
          ……………………………………………………….
      2. Which cleaning agent above is not environmental friendly? Explain
  25. The molecular formula of a hydrocarbon is C6H14. The hydrocarbon can be converted into two other hydrocarbon as shown by the equation below:
    C6H14 → C2H6 + X
    1. Name and draw the possible structural formula of X
    2. State and explain the observations that would be made if a few drops of bromine water were added to a sample of X
    3. Write an equation for the complete combustion of C3H8
  26.  
    1. Give the names of the following
      1. CH3CH2CH3
      2. CH3CCCH3
    2. Ethene is used in making polyethene bag in a process called polymerization
      1. Name the type of polymer that is formed when ethane polymerise
      2. Describe a simple chemical test that can be used to identify ethane gas in the laboratory
    3. Study the information in the table below and answer the questions that follow:-
       No. of carbon atoms  R.M.M of the Hydrocarbon
       2  28
       3  42
       4  56

      1. Write the general formula of the hydrocarbons in the table above
      2. Determine the molecular of a hydrocarbon with 5 carbon atoms and draw its structural formula
        Molecular formula
        Structural formula
    4. Study the scheme below and answer the questions that follow
      schemeq26dorgchem
      1.  Name the reagents in
        Step I ……………………………
        Step II ……………………………
        Step IV ………………
      2. Write an equation for the complete combustion of CH≡CH
      3. Give two uses of CH4
  27. Give the systematic names of the following compounds;
    1.  
      2 methyl prop 1 ene
    2. CH3CH2CH2C≡ CH
  28. Study the data given in the following table and answer the questions that follow. The letters are not the actual symbols of elements.
     Element  Number of protons  Melting Point  Bpt oC
     A  11  98  890
     B  12  650  1110
     C  13  60  2470
     D  14  1410  2360
     E

     15  442
     590
     280
     F

     16  113
     119
     445
     G  17  -101  -35
    H 18  -189  -386

    1. State and explain the trend in melting point in A B C
    2. Explain why the melting point and boiling points of element D is the highest
    3. Explain why the element represented by letter E has two melting point values
    4. Write down the chemical formula between element C and sulphate ions
    5. Name the chemical family in which H belong and state one use of the element
    6. What is the nature of the oxide of the elements represented by letters C and F?
  29. Study the information in the table below and answer the questions that follow
     No. of carbon atoms  R.M.M of the Hydrocarbon
     2  28
     3  42
     4  56

    1. Write the general formula of the hydrocarbons in the table
    2. Predict the relative atomic mass of the hydrocarbons with 5 carbon atoms
    3. Determine the relative atomic mass of the hydrocarbon in (ii) above and draw its structural formula (H=1.0, C=12.0)
  30. Substance “M” with a general formula C2Hy burnt in chlorine gas with a red flame producing a cloud of black specks and colourless gas G.
    1. State the collective name for compounds which ‘M’ belongs
    2. With reason, state the identity of the black specks and colour gas “G”.
  31.  
    1. 2.63g of a solution of sodium chloride at 20.0oC was reacted with silver nitrate. After filtration, washing and drying, 2.36g of silver chloride was obtained. Determine the solubility of sodium chloride at 20.0oC . (Na=23, Cl= 35.5, Ag = 108)
    2. Determine the number of moles of carbon (IV) Oxide gas produced when sodium carbonate reacted with dilute sulphuric (VI) acid (Molar gas volume =24dm3)
  32. Write down all the isomers of but-z-ene and give their IUPAC names
  33.  A hydrocarbon compound Z decolourizes bromine liquid in the presence of light but does not decolourize acidified potassium manganate (VII). Name and draw the structural formula of the eighth member of this homologous series
  34.  
    1. What is meant by isomerism?
    2. Draw and name two isomers of Butyne

Answers

  1.   
    1. Bromine decolorized immediately in ethane gas √1
    2. Temperature between150°C - 250°C or temperature of 180°C
    3. arbon (IV) oxide or CO2(g)
  2.  
    1. Butane
    2. Manufactures of cooking fats and margarine
  3.  
    orgchemans3 
  4.   
    1. Existence of cpds with the same molecular formula but different structural formula/arrangement of atoms
    2.  
      orgchem4b
  5.   
    1. 2.5
    2. Q Group 1 ✓½, Period 4 ✓½
      R Group 2 ✓½, Period 3 ✓½
  6.   
    1.  
      structural formula of W
    2. 2,3 dichlorobutane
    1. To produce simpler hydrocarbons of industrial importance e.g. ethane which is widely used
    2. - Elevated temperature / high temperature 900 C
      - Catalyst
    3.  
      1 chloro dimethyl propane
  7. Reagent: concentrated sulphuric acid
    Condition: temperature 180o C
  8.   
    1. H2CHClCHClCH2CH3
      Name: 2, 3 dichloropentane
    2.   
      1. Structural Formula
        pent 13 diene
      2. IUPAC name
        pent – 1,3 – diene
  9. Isotopes are atoms of the same element with same atomic number but different mass numbers while isomers are compounds with the same molecular formula but different structural formula
  10. Addition polymerization. 1
  11.   
    1. When gases combine they do so in volume which bear a simple ratio to one another and to the product if gaseous under standard temperature and pressure
  12. CH  +  2O2(g) → CO2(g) + 2H2(l)
    10cm3   20cm3      10cm3✓½
    Volume of O2 = 20/100 x 150
    = 30cm3
    Remaining volume of O2 = 30 − 20=10 cm3
    Total volume of the gases = 20+10+10
    = 40cm3
  13.  
    orgchemans14
  14. T2 = 690 × 15 × 259
              650 × 105
    = 39.3K
    = - 233.7° C
  15. CH2 =CH2(g) + H2SO4(l) → CH3CH2OSO3H(aq) 1 mark
  16.   
      1. Fractional Column.
      2. fractional distillation.
      3. different boiling points.
        1. A
        2. F
        3. B
    1. G – road making or water proofing
      C jet fuel or cooking and lighting.
    2.  
      orgchem17c
  17.   
    1. ethyne
    2. Alkynes – because it has triple bond between the two carbon atoms
    3. Water and calcium carbide
    4. - Colourless, odourless
      - less denser than air
      - Insoluble in water but soluble in organic solvents
    5. Step 1 - Hydrogenation
      Step 2 - Halogenations
    6.  
      orgchemans18vi
    7. Carbon (IV) Oxide
  18.   
    1. Gas /vapour
    2.  B - It has the second lowest boiling point thus second lowest molecular mass
    3. C is impure since it boils over a range of temperature
    4. It is boiled heated and the vapour of the components condense at different temperatures
    5. - Liquid air
      - Crude oil
  19.   
    1.   
      1. Bitumen it has the highest boiling point
      2.  Fractional distillation; during distillation petrol would distill off at 175oC, while diesel will distill at 350C
      3. Each component is a mixture of hydrocarbons which have different boiling points
      4. Methane, CH4, EthaneC2H6 propane, C3H8, Butane C4H10
    2.   
      1. Burning in limited amount of air will produce carbon monoxide (carbon (II) Oxide) which is poisonous
      2. Manufacture of Tar used in road tarmacking sealing of leakages on roofs
  20.   
    1.   
      1. Calcium carbide – CaC2
      2. Over water method
        collection of ethyne
      3. CaC2(s)+ 2H2O(s)+ 2H2O(l) → Ca(OH)2(aq) + C2H2(g)
      4. C2H2 + 2I2 → C2H2I2
      5. The reaction if highly exothermic hence sand helps to absorb excess heat.
    2.   
      1. A reaction in which an organism acid reacts with an alkanol to form a sweet smelling compound called ester.
      2. CH3COOCH3 + H2O → CH3COOH + CH3OH
      3. Hydrolysis
    3.   
      1. F – Aluminium oxide – Al2O3
        N – C6H14 – Hexane
      2. Cracking
    4. A fuel
  21.   
    1.   
      1. Cracking of crude oil fractions. 1
      2. Temp – 400 – 5000c
        Pressure – 200 – 500 atmospheric Any 2 = 1
        Catalyst – Finally divided iron.
      3. 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(l)
      4. - Manufacture of nitrate fertilizers. 1
        - Manufacture of explosives.
        - Purification of metals.
    2. - Red brown gas 1 with pungent irritating smell due to reduction of HNO3 to NO2
      - Blue 1 solution due to formation of Cu (NO3)2
  22.   
    1.   
      1. 2-bromo propene or 2- bromo prop-i-ene
      2. Pent-i-ene
    2.   
      1. Changes form orange to Green
      2. Effervescence//bubbles of gas produced
    3. Step 1
      - Fermentation of glucose
      Glucose broken down in obscene of oxygen using enzymes
      - Dehydration of ethanol; using concentrated sulphuric (VI) acid and high temperature of 170oC

      Step II
      - Dehydration of ethanol; using concentrated sulphuric (VI) acid and high temperature of 170oC
    4. Compound A
    5. - release chlorine gas which destroy ozone layer
      - Chlorine gas combines with vapour in atmosphere to form acid rain which destroy vegetation
      - Chlorine gas can cause respiratory diseases
  23.   
    1. 2,2 – dimethyl pentane
    2.   
      1.   
        1. carbon IV oxide.
        2. Hydrogen gas.
        3. Propane.
      2.   
        1. Hydrogenation.
        2. Neutralization
        3. substitution
      3. CH3CH2CH2O(l) + 902 (g) → 6 CO2 (g)+ 8 H2O(l)
      4. Condition Presence of U.V light
        Reagents – Chlorine gas
      5. CH3CH2COOH + NaOH → CH3CH2COONa + H2O(l)
        Mole ratio :
        74 tones of acid  =  96 tones of salt
        21.9                  = ?            
        21.9 × 96 = 28.4 tones
              74
        Or 21.9 = 0.29 moles of salt
              74
        = 0.29 × 96 = 28.4 tones
      6.   
        1.  
          orgchemans24vi
        2. use in making – Plastic crates plastic boxes plastic ropes

    3.   
      1.   
        1. soapy detergent
        2. Soap less detergent
      2. Soap less Detergent - non biodegradable.
  24.   
    1.  
      orgchemans25
    2. Bromine water is decolourised because X is unsaturated or has a (-C = C-) double bond.
    3. C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)
  25.   
    1.   
      1. Propane
      2. But - 2 - yne
    2.   
      1. Ploythene
      2. Bubble pass ethane gas in acidified KMnO4 or acidified K2Cr2O7
    3.   
      1. CnH2n
      2. C5H10
    4.   
      1. Step I – hydrogen
        Step II – Hydrogen chloride
        Step IV – Sodalime
      2. 2CH = CH(g) + O2(g) → 4CO2(g) + 2H2O(l)
        - A fuel
        - Manufacture of methanol
        - Manufacture of methanol
  26.   
    1. 2 – Methylprop – 1 - ene 
    2. Pent – 4 – yne
      ✓ 1 mark
      ✓ 1 mark [Total 12 marks]
  27.   
    1. The melting point increases from A to C this is due to increase in number delocalized electron hence increase in the strength of metallic bond.
    2. forms a giant structure with strong covalent bonds. Hence high melting.
    3. It exhibits allotopy ie may exist as two different form in the same state.
    4. C2(SO4)3
    5. Noble gases or inert
      - Used in filament bubls
      - Used to produce an inert atmosphere in high temperature inetallurgical processes e.g welding.
    6. C is amphoteric oxide
      - F acidic it is non –metal oxide.
  28.    
    1. CnH2n, where n = No. of carbon atoms
    2. 70
    3. C5H10, CH3CH=CHCH2CH3
      OR CH3CH2CHCH2= CH2
  29.   
    1. Hydrocarbon. 1
    2. Black specks is carbon
      Colourless gas is steam 1 3
      Hydrocarbon burn in air to form carbon ½ and water½
  30.   
    1. NaCl(aq)AgNO3(aq) → NaNO3(aq)+ AgCl(s)
      Moles of AgCl= Mass
                            R.F.M
      = 2.36/143.5
      = 0.016446moles
      Mole ratio NaCl : AgCl
                         1  : 1
      Moles of NaCl = 0.61446moles
      Mass of NaCl = RFM x moles
      = 58.5 x 0.016446
      = 0.962091g
      Mass of solvent (water) = 2.63 – 0.962091
      = 1.667909g
      1.667909g of water dissolves 0.962091g of NaCl
      100g of water dissolves = 100 x 0.962091g
                                              1.667909
      = 57.68/100g of water
    2. 24000cm3= 1mol
      80cm3 = 80x1
                   2400
      = 0.00333moles
  31.   
    1. CH3CH = CHCH3 – But-2-ene
    2. 2– methyl 1 prop-2-ene
    3. CH2 = CHCH2CH3 – But-1-ene
  32. Octane
    or CH3CH2CH2CH2CH2CH2CH2CH3
  33.   
    1. Existence of same molecular formula but different structural formula √1
    2.  
      isomers of butyne

Download Organic Chemistry 1 Questions and Answers - Chemistry Form 3 Topical Revision.


Tap Here to Download for 50/-





Join our whatsapp group for latest updates
Read 4641 times Last modified on Friday, 16 July 2021 07:57
Print PDF for future reference