14. Organic chemistry 1 Questions and Answers

Organic chemistry 1 Questions

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

 (a) What observation would be made in process K?

 (b) Name another conditions necessary for process J to take place  

 (c) Give the name of substance V

2.  But-z-ene undergoes hydrogenation according to the equation given below

CH₃CH = CHCH_3
(g) + H_2(g) CH₃CH₂CH₂CH_3(g)

 (a) Name the product formed when but-z-ene reacts with hydrogen gas

 (b) State one industrial use of hydrogenation  

3.  Write the structures of the following compounds:-

  (a) But—2-yne  

  (b) 2,2-dimethylpropane

4.  a)What is meant by Isomerism?

 b) Draw and name two Isomers of butane.  

5.  Study the information in the table below and answer the questions that follow:

 a) Write the electron arrangement of element P.

 b) 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:

CH₃ – CH – CH – CH₃

Cl Cl

  (a) Give the structural formula and name of compound W

 (b) Name compound X  ……………………………………………………………………

7. In petrol chemical industries, long chain alkanes are broken down in to simpler substances

in a process called cracking

a) Why is cracking necessary?

b) State the two conditions required in cracking

c) Draw the structure of 1-chloro-2, 2-dimethylpropane

8.  In a reaction an alcohol K was converted to hex-1-ene

 a) Name reagent and condition necessary for the reaction in 6 (a) above to occur

9.  (a) Give the IUPAC systematic names of compounds Q and R

Q: CH₂CHClCHlCH₂CH₃

   R: CH₃CHClCH₂ClCH₃

  (b) The organic compounds Q and R in (b) above, are formed when one mole of hydrocarbon

N reacts with two moles of hydrogen chloride gas;

 (i) Structural formula of N

(ii) 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

 Name the type of polymerisation undergone by ethene in the reaction above

12.  (a) 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:-

 (i) 3-chlorohex-l-yne  

 (ii) 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:

(a) (i) What is the name of the apparatus above

(ii) What is the name of the process which is used in separation of crude oil  

(iii) What physical property of compounds in the mixture does the separation depend

(iv) Use the letter A to G to describe where the following could be formed:.

I. The fraction that represents gases

II. The fraction that represents the largest molecules

III. The fraction that represents liquids with the lowest boiling points  

(b) State the use of product produce at

G………………………………………………………………………………………

C……………………………………………………………………………………….

(c) 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:-

(i) Give the name of the substance CH  CH …………………………………………

 (ii) To which group of hydrocarbons does the substance in (i) above belong?

 (iii) Give two reagents that can be used to prepare the substance named in (i) above

 (iv) State two physical properties of the substances in (i) above  

 (v) Give the names to the process in step I and 2

 (vi) Write an equation to show how substance A is formed

(iv) 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

(a) The components have the following average relative molecular masses not necessarily in that

order; 282, 184, 44 and 128.

(a) (i) What is the physical state of B at the position marked Q?

(ii) Which component has an average relative molecular mass of 128? Explain

(iii) State with a reason whether C is pure or impure

(iv) Explain how the mixture is separated into its components

(v) Name two naturally occurring mixtures that are separated using this process

20.  The diagram below represents a large-scale fractional distillation plant used to separate

the components A, B, C and D in a mixture

(a) The components have the following average relative molecular masses not necessarily in that

order; 282, 184, 44 and 128.

(a) (i) What is the physical state of B at the position marked Q?

(ii) Which component has an average relative molecular mass of 128? Explain

(iii) State with a reason whether C is pure or impure

(iv) Explain how the mixture is separated into its components

(v) Name two naturally occurring mixtures that are separated using this process

21.  a) The table below gives information about the major constituents of crude oil. Study it and

answer the questions that follow:

 i) Which of the constituents of crude has molecules with the highest number of carbon

atoms? Explain  

 ii) Name the process you would use to separate a mixture of petrol and diesel and explain how

the separation takes place

 iii) Explain why the constituents of crude oil do not have a sharp boiling point

  iv) Name the gas that is likely to be a constituent of crude oil and write its formula  

 b) i) What condition could cause a poisonous gas to be formed when kerosene is burnt.

Explain

 ii) Give one use of bitumen

22.  (a) The set-up below was used to prepare ethyne gas

(i) Identify solid E  

(ii) Complete the diagram to show how the gas can be collected  

(iii) Write an equation to show how the gas is formed

(iv) Complete the equation below: )

C₂H₂ + 2I₂  

(v) What is the role of sand in the experiment?

(b) (i) Explain the meaning of esterification  

(ii) Complete the equation below  :  

CH₃COOCH₃ + H₂O

(iii) What type of reaction is occurring above

(c) Given the reaction:

C₈H₁₈ N + C₂H₄

(i) Identify substance:

F………………………………… N………………………………

(ii) Name the process represented above?  

(d) Give one use of substance N

23.

(i) Name another source of hydrogen apart from electrolysis of water

(ii) What conditions are necessary for step III to occur?

(iii) Write the equation for the formation of colourless gas Q  

(iv) Give one use of nitric (V) acid

(b) State and explain the observations that would be made if a sample of copper metal is

heated with concentrated nitric (V) acid  

24.  (a) Give the systematic names of the following compounds:-

(i) CH₂ = C – CH₃  ………………………………………………………………..

Br

  (ii) CH₃CH₂CH₂C  CH ………………………………………………………..

 (b) State the observations made when buton-l-ol reacts with:-

  (i) Acidified potassium dichromate (VI) solution

(ii) Potassium metal

 (c) Ethanol obtained from glucose can be converted to ethene as shown below:-

C₆H₁₂O₆ C₂H₅OH C H₂ = CH₂

Name and describe the processes that take place in steps I and II

 (d) 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:-

 (e) Give two ways how the disposal of polymers such as polychloroethene by burning pollutes

  the environment  

25.  (a) Name the following compounds (CH₃)₃ C CH₂ CH₂ CH₃    

 Use the flow chart below to answer the questions that follow:-

(b) (i) Name the following :-

I. Gas S ……………………………………………………………….……. ( )

II. Gas P …………………………………………………………………

III. J ……………………………………………………………………….

(ii) Name the processes involved in the following steps:

I. Step I  …………………………………………………………………………..  

II. Step II  …………………………………………………………………………….  

III. Step III …………………………………………………………………………….  

(iii) Write a chemical equation for the complete combustion of substance M

(iv) Name the condition and reagent in step III

Condition ……………………………………………………………………………………  

Reagent …………………………………………………………………………………….  

(v) 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)  

(vi) Draw the structure of polymer K

II. State one use of the above polymer

………………………………………………………………………………………………….

(c) (i) Name the class to which the following cleansing agents belong:-

i) ……………………………………………………  

(ii) ……………………………………………………….  

II. Which cleaning agent above is not environmental friendly? Explain  

26.   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

(i) Name and draw the possible structural formula of X

(ii) State and explain the observations that would be made if a few drops of bromine water

were added to a sample of X

(iii) Write an equation for the complete combustion of C₃H₈

27.  (a) Give the names of the following

 (i) CH₃CH₂CH₃

 (ii) CH₃CCCH₃

 (b) Ethene is used in making polyethene bag in a process called polymerization

  (i) Name the type of polymer that is formed when ethane polymerise

 (ii) Describe a simple chemical test that can be used to identify ethane gas in the laboratory

(c) Study the information in the table below and answer the questions that follow:-

  i. Write the general formula of the hydrocarbons in the table above

  ii. Determine the molecular of a hydrocarbon with 5 carbon atoms and draw its structural formula

Molecular formula

   Structural formula

 (d) Study the scheme below and answer the questions that follow

(i) Name the reagents in  

 Step I ……………………………

Step II ……………………………

Step IV ………………

 (ii) Write an equation for the complete combustion of CH CH  

 (iii) Give two uses of CH₄

28. Give the systematic names of the following compounds;

  i)CH₃ = C-CH₃  

CH₃

  ii)CH₃CH₂CH₂C≡ CH

29.  Study the data given in the following table and answer the questions that follow. The letters

are not the actual symbols of elements.

 (i) State and explain the trend in melting point in A B C

 (ii) Explain why the melting point and boiling points of element D is the highest

 (iii) Explain why the element represented by letter E has two melting point values

 (iv) Write down the chemical formula between element C and sulphate ions

 (v) Name the chemical family in which H belong and state one use of the element

 (vi) What is the nature of the oxide of the elements represented by letters C and F?  

30. a) The table below gives information about the major constituents of crude oil. Study it and

answer the questions that follow:

 i) Which of the constituents of crude has molecules with the highest number of carbon

atoms? Explain  

 ii) Name the process you would use to separate a mixture of petrol and diesel and explain how

the separation takes place

 iii) Explain why the constituents of crude oil do not have a sharp boiling point

  iv) Name the gas that is likely to be a constituent of crude oil and write its formula  

 b) i) What condition could cause a poisonous gas to be formed when kerosene is burnt.

Explain

  ii) Give one use of bitumen

31.   Study the information in the table below and answer the questions that follow

 i) Write the general formula of the hydrocarbons in the table  

 ii) Predict the relative atomic mass of the hydrocarbons with 5 carbon atoms

 iii) Determine the relative atomic mass of the hydrocarbon in (ii) above and draw its

structural formula (H=1.0, C=12.0)  

32.  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.

 (a) State the collective name for compounds which ‘M’ belongs  

(b) With reason, state the identity of the black specks and colour gas “G”.

33.  2.63g of a solution of sodium chloride at 20.0^oC was reacted with silver nitrate. After filtration,

 washing and drying, 2.36g of silver chloride was obtained. Determine the solubility of sodium

 chloride at 20.0^oC . (Na=23, Cl= 35.5, Ag = 108)

 (b) Determine the number of moles of carbon (IV) Oxide gas produced when sodium

carbonate reacted with dilute sulphuric (VI) acid (Molar gas volume =24dm³)

34.  Write down all the isomers of but-z-ene and give their IUPAC names

35.  (a) 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

36.  (a) What is meant by isomerism?

 (b) Draw and name two isomers of Butyne  

Organic chemistry 1 Answers

1.  a) Bromine decolorized immediately in ethane gas √1

b) Temperature between150°C – 250°C or temperature of 180°C

c) Carbon (IV) oxide or CO_2(g) √

2.  (a) Butane

 (b) Manufactures of cooking fats and margarine

3.  (a)

(b)

4.  a) Existence of cpds with the same molecular formula but different structural

formula/arrangement of atoms

b)

n – butane/ ½  2 – butane/½

l – butane/ But-2-ene 2 – methyl

But-1-ene prop-1-ene

5.  a) 2.5

 b) Q Group 1 ½,  Period 4 ½

  R  Group 2 ½, Period 3 ½

6.  a) H  H  H  H

W- H C –  C =  C  C- H

H H

7.  a) To produce simpler hydrocarbons of industrial importance e.g. ethane which is widely used

 b) Elevated temperature / high temperature 900 C

Catalyst

 c) HC – C CH₃

8.  a) Reagent concentrated sulphuric acid  

Condition temperature 180^o C  

9.  a) H₂ CHCL CHCLCH₂CH₃

  Name: 2, 3 dichloropentane

b) i) Structural Formula

H H H

H – C = C – C = C – C – H

H H H

 ii) IUPAC name

  pent – 1,3 – diene  

10.  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

11.  Addition polymerization. ^√1

12.  (a) 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

13.   CH4 + 2O_2(g)   CO_2(g) + 2H_2(l)

  10cm³ 20cm³ 10cm³

Volume of O₂ = 20 x 150

  100

    = 30cm³

Remaining volume of O₂ = 30-20=10cm³

Total volume of the gases = 20+10+10  

  = 40cm³

H H H H

14.  (i) H – C  C – C – C – C – C – H

Cl H H H

H

  (ii) H – C – O – H

H

15.  

 T₂ = 690 X 15 X 259√

650 X 105

= 39.3K√

= – 233.7° C√

16.   CH₂ =CH_2g + H₂SO_4(L) ________ CH₃CH₂OSO₃H_(aq)
√ 1 mark

1 7  (a) i) Fractional Column.  

  ii) fractional distillation.  

iii)different boiling points.  

IV I A II F III B

b) G – road making or water proofing

  C jet fuel or cooking and lighting.

18.   (i) ethyne

 (ii) Alkynes – because it has triple bond between the two carbon atoms

 (iii) Water is calcium carbide

 (iv) – Colourless, odourless

    -less denser than air

 – Insoluble in water but soluble in organic solvents

  (v) Hydrogenation

 (vi) Halogenations

(vii)

 (viii) Carbon (IV) Oxide

  (ix) Nitrogen I Oxide (N₂O)

19.  (a) (i) Gas /vapour

  (ii) B – It has the second lowest boiling point thus second lowest molecular mass

  (iii) C is impure since it boils over a range of temperature

  (iv) It is boiled heated and the vapour of the components condense at different temperatures

  (v) – Liquid air

  – Crude oil

20.  (a) (i) Gas /vapour

  (ii) B – It has the second lowest boiling point thus second lowest molecular mass

  (iii) C is impure since it boils over a range of temperature

  (iv) It is boiled heated and the vapour of the components condense at different temperatures

  (v) – Liquid air

  – Crude oil

21.  a)  i) Bitumen it has the highest boiling point

ii) Fractional distillation; during distillation petrol would distill off at 175C, while diesel

will distill at 350C

iii) Each component is a mixture of hydrocarbons which have different boiling points

iv) Methane, CH₄, EthaneC₂H₆ propane, C₃H₈, Butane C₄H₁₀

 b)  i) Burning in limited amount of air will produce carbon monoxide (carbon (II) Oxide)

which is poisonous

ii) Manufacture of Tar used in road tarmacking sealing of leakages on roofs

22.  A. (i) Calcium carbide – CaC₂

  (ii) Over water method

(iii) CaC_2(s) + 2H₂O_(s) + 2H₂O_(l)   Ca(OH)_2(aq) + C₂H_2(g)  

(iv) C₂H₂ + 2I₂  C₂H₂I₂

(v) The reaction if highly exothermic hence sand helps to absorb excess heat.

B. (i) A reaction in which an organism acid reacts with an alkanol to form a sweet smelling

compound called ester.

  (ii) CH₃COOCH₃ + H₂O CH₃COOH + CH₃OH  

(iii) Hydrolysis

C (i) F – Aluminium oxide – Al₂O₃

N – C₆H₁₄ – Hexane

  (ii) Cracking  

D. A fuel  

23.  i) Cracking of crude oil fractions. √1

ii) Temp – 400 – 500⁰c

Pressure – 200 – 500 atmospheric Any 2 = 1

Catalyst – Finally divided iron.

iii) 4NH₃(g) + 5O₂(g) 4NO(g) + 6H₂O(l)

  iv)  – Manufacture of nitrate fertilizers. √1

– Manufacture of explosives.

– Purification of metals.

 b)  – 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

24.  (a) (i) 2-bromo propene or 2- bromo prop-i-ene

  (ii) Pent-i-ene

  (b) (i) Changes form orange to Green  

  (ii) Effervescence//bubbles of gas produced

(c) 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 170^oC

Step II

• Dehydration of ethanol; using concentrated sulphuric (VI) acid and high temperature of 170^oC
  

(d) Compound A

(e) – 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

25.   (a) (i) 2,2 – dimethyl pentane

 (b) I carbon IV oxide.

  II Hydrogen gas.

  III Propane.

1. I Hydrogenation.
   

II Neutralization

III substitution

(iii) CH₃CH₂CH₂Ol + 902 _(g) 6 CO_2
(g) + 8 H₂O_(l)

(iv) Condition Presence of U.u light

Reagents – Chlorine gas

(v) CH₃CH₂ CooH + NaoH CH₃ CH₂ COONa + H₂O_(c)

  Mole ratio :

  74 tones of acid 96 tones of salt

  21.9 21.9 X 96 = 28.4 tones

74

  Or 21.9 = 0.29 moles of salt

  74

  = 0.29 X 96 = 28.4 tones

(iv) I H CH

C C

H H  n

(ii) use in making – Plastic crates plastic boxes plastic ropes

( c) I (i) soap detergent

(ii) Soap less detergent

  II Soap less Detergent – non biodegradable.

26. (i) But-i-ene Or (accept any 1)

  But-z-ene

(ii) Bromine water is decolourised because X is unsaturated or has a (-C = C-) double bond.

(iii) C₃H_8(g) + 5O_2(g) 3CO_2(g) + 4H₂O_(l)

27.  a)  i) Propane

ii) But- 2 –yne

 b)  i) Ploythene

ii) Bubble pass ethane gas in acidified KMnO4 or acidified K2Cr2OT

 c)  i) CnH2n

ii) @5H10

 d)  i) Step I – hydrogen

Step II – Hydrogen chloride

Step IV – Sodalime

ii) 2CH = CH(g) + O2(g) ________ 4CO2(g) + 2H2O(L)

• A fuel
  
• Manufacture of methanol
  
• Manufacture of methanol
  

28.  i) 2 – Methylprop – l ene  1 mark

ii) Pent – L – yne  1 mark  [Total 12 marks]

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.

 D forms a giant structure with strong covalent bonds. Hence high melting.

It exhibits allstrophy ie may exist as two different form in the same state.

C2 (so4)3

Noble gases or inert

Used in filament bubls

Used to produce an inert atmosphere in high temperature inetallurgical processes e.g welding.

C is amphoteric oxide

F acidic it is non –metal oxide.

Ethene

^H
H

C= C

_H
H

Acidified potassium Manganate VI abromine water it from a colourless solution

CH₂CH₂ + H₂ CH₃CH₃

Nickel catalyst

30.  a)  i) Bitumen it has the highest boiling point

ii) Fractional distillation; during distillation petrol would distill off at 175C, while diesel

will distill at 350C

iii) Each component is a mixture of hydrocarbons which have different boiling points

iv) Methane, CH₄, EthaneC₂H₆ propane, C₃H₈, Butane C₄H₁₀

 b)  i) Burning in limited amount of air will produce carbon monoxide (carbon (II) Oxide)

which is poisonous

ii) Manufacture of Tar used in road tarmacking sealing of leakages on roofs

31.  i) C_nH_2n, where n = No. of carbon atoms

ii) 70

iii) C_sH₁₀, CH₃CH=CHCH₂CH₃

OR CH₃CH₂CHCH₂= CH₂

32.  (a) Hydrocarbon. √1

 (b) Black specks is carbon

  Colourless gas is steam  √1 3

  Hydrocarbon burn in air to form carbon √ ½ and water√½

33.  NaCl_(aq) AgNO_3(aq) NaNO_3(aq) + AgCl_(s)

  Moles of AgCl= Mass

R.F.M

= 2.36

143.5

= 0.016446moles

Mole ratio Nacl: AgCl

1 :1

Moles of NCl = 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

33.  24000cm³ = 1mol

80cm³ = 80×1

  2400

= 0.00333moles

34..  (i) CH₃CH = CHCH₃ – But-z-ene  

 (ii) CH₃C = CH₂ 2– methyl 1 prop-I-ene

 CH₃

 (iii) CH₂ = CHCH₂CH₃ – But-I-ene  

35.   (a) Octane

  or CH₃CH₂CH₂CH₂CH₂CH₂CH₂CH₃

36.  a) Existence of same molecular formula but different structural formula √1

b) i)