CHEMISTRY PAPER 1 - 2019 LANJET JOINT MOCK EXAMINATION

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  1. Write an equation to show the effect of heat on the nitrate of: -                               (2marks)
    1. Potassium
    2. Silver
  1. Study the diagram below and use it to answer the questions that follow.
    chem1 q2 qsns
    1. State the observation made in the combustion tube.                                           (1mark)
    2. Write an equation for the reaction that took place in the combustion tube.        (1mark)
    3. Name gas P                                                                                                          (1mark)
  2. A typical electrolysis cell used a current of 40,000 amperes. Calculate the mass (in Kg of aluminum produced in one hour.  (Al = 27) (Faraday = 96500Coulombs).(3marks)
  1. Oxygen is obtained on large scale by the fractional distillation of air as shown on the flow chart below.
    chem1 q4 qsns
    1. Identify the substance that is removed at the filtration stage.                                  (1mark)
    2. Explain why Carbon (IV) oxide and water are removed before liquefaction of air. (1mark)
    3. Identify the component that is collected at -186°C.                                              (1mark)
  2. The flow chart below shows steps used in the extraction of zinc from one of its ores
    chem 1 q5 qsns
    1. Name the process that is used in step 2 to concentrate the ore.                (1mark)
    2. Write an equation for the reaction which takes place in step 3. (1mark)
    3. Name one use of lead.                                                                               (1mark)
  1. In an attempt to prepare a gas, a student added concentrated hydrochloric acid to Potassium manganate (VII). The products were then passed through two wash bottles containing water and concentrated sulphuric acid
    1. Name the gas prepared…………………………………………………………  (1mark)
    2. State the purpose of wash bottle:
      1. Containing water?                 (1mark)
      2. Containing concentrated sulphuric acid?    (1mark)
  1. Starting with 50 cm3 of 2M sodium hydroxide, describe how a solid sample of pure sodium sulphate crystals can be prepared in the laboratory. (3 marks)
  1. The grid below shows a part of the periodic table. The letters do not represent the actual symbols. Use it to answer the questions that follow: -
    chem1 q8 qsns
    1. Why is it possible to place element E in both group I and VII?     (1mark)
    2.  
      1. What type of structure formed when element N and P react?                               (1mark)
      2. Why do most of the elements react?                                                          (1mark)
  2. The table below gives information about the major alkanes which are constituents of crude oil. Study it and answer the questions that follow:.
    chem1 q9 qsns
    1. Why is petrol highly flammable than diesel?                                                           (1mark)
    2. Explain why alkenes and alkynes are not contained in crude oil.                           (1mark)
    3. Give one use of bitumen.              (1mark)
  3.  
    1. Explain the importance of the high percentage of nitrogen in air.       (1mark)
    2. Why is nitrogen used for storage of semen in artificial insemination?     (1mark)
  4. A solution of bromine gas in water is an example of a chemical reaction in a state of balance. The reaction involved is represented by the equation below:
    chem1 q11 qsns
    State and explain the observations made when hydrochloric acid is added to the mixture.     
  5. Concentrated hydrochloric acid that is 35% pure has a density of 1.18g/cm3. Calculate its concentration in moles per litre. (H=1.0 Cl=35.5)   (3marks)
  6.  
    1. State the reason for using Argon in electric light bulbs.           (1mark)
    2. Study the information in the table below and answer the questions that follow. The letters do not represent the actual symbols of the elements.

      Element

      Electronic configuration

      Boiling point

      X

      Y

      Z

      2.7

      2.8.7

      2.8.8.7

      -188oC

      -35oC

      59oC


      1. What is the general name given to the group in which the elements?            (1mark)
      2. Identify the element that is a solid at room temperature. Explain                        (1mark)
  7. Bond energies for some bonds are tabulated below: -

    BOND

    BOND ENERGY KJ/mol

    H – H

    436

    C = C

    610

    C- H

    410

    C - C

    345


    Use the bond energies to estimate the enthalpy for the reaction.                               (3marks)
    chem1 q14 qsns
  8. The diagram below shows three methods for collecting gases in the laboratory  
    chem1 q15
    1. Name the methods A and B.                                                                                 (1mark)
    2. From the methods above, identify one that is suitable for collecting Sulphur (IV) oxide.  Explain.     (2 mark)
  9. The structure below represents a cleansing agent.
    chem1 q16 qsns
    1. State the type of cleansing agent represented above. (1 mark)
    2. State two disadvantage of using the other type cleansing agent. (2 marks)
  10. The diagram below represents a set-up that can be used for the electrolysis of dilute sulphuric acid
    chem1 q17 qsns
    1. Name the electrodes A and (1mark)
    2. Write an equation for the reaction taking place at electrode B.                            (1mark)
    3. What happens to the concentration dilute sulphuric acid as the reaction continues?(1mark)
  11.  
    1. State the graham’s law of diffusion.                                                                (1mark)
    2. Calculate the relative formula mass of gas X given that the time taken by equal volume of nitrogen gas and gas X to diffuse through the same hole is 10 seconds and 20 seconds respectively.                                                                                           (2mks)
  1.  
    1. Complete the following nuclear equation.      (1mark)
      chem1 q19 qsns
    2. 100g of a radioactive substance was reduced to 12.5g within 15.6 years. Determine the half-life of the substance.    (2marks)
  2. Wooden splints F and G were placed in different zones of a Bunsen burner flame. The diagram below gives the observations that were made.
    chem1 q20 qsns
    1. Explain the difference between F and                                                 (1mark)                                                                      
    2. Name the type of flame that was used in the above experiment.                        (1mark)
  3.  
    1. Identify the acid and base in the forward reaction given by the equation below: (1mark)
    2. Using the above equation and your answer in (a) above, define the term acid.(1mark)
  4. Sulphur exists in two crystalline forms.
    1. Name one crystalline form of Sulphur.                                                                   (1mk)
    2. State two uses of Sulphur.                                                                                      (2mks)
  5. Study the set up below and answer the questions that flows
    chem1 q21 qsns
    State all the observations that would be made when the circuit is completed (3marks)
  6. The diagram below shows the catalytic oxidation of ammonia gas. Use it to answer the questions thatfollow: -   
    chem1 q24 qsns                                                                                                        
    1. What metal could rod M be made of?                                                                     (1mark)
    2. State and explain two observations made inside the conical flask.                          (2marks)
  7. State two distinctive features of a dynamic equilibrium.                                       (2marks)
  8. 3.1 of an organic compound containing Carbon hydrogen and oxygen only produced 4.4g of Carbon (IV) oxide and 2.0g of water on complete combustion.
    1. Calculate its empirical formula.                                                                      (2 marks)
    2. Calculate in molecular formula if its formula mass is 62.                               (1 mark)
  9.  
    1. Nitric (V) acid prepared in the laboratory is yellow in colour. What causes the yellow colour? (1 mark)
    2. State any two observations that would be made when concentrated nitric(V) acid is added to copper turnings.  (2 marks)
  10. The curves below were obtained when equal volumes of HCl acid of same concentration were reacted with 25.0g of Mabel chips. In one case, the acid was first warmed to a high temperature.
    chem1 q28 qsns
    1. Which curve represents the reaction involving warm hydrochloric acid?      (1 mark)
    2. Suppose a graph of volume of CO2 produced against time was plotted, draw on the same axes a sketch to show the graphs of the reaction above and label them as warm acid and cold acid. (2 marks)


MARKING SCHEME

  1.  
    CHEM11111111111111
  2.  
    1. A brown solid is formed p1
    2.  
      CHEM11111111Q2
    3. Carbon (II) Oxide. p1
  1. Q = 40000 x 60 x 60 = 144000000cp1
    Mass of Al = 144000000 x 27p1
                             3 x 96500
                    = 13.43kgp1
  2.  
    1. Dust particlesp1
    2. They readily solidify hence may block the pipesp1
    3. Argonp1
  3.  
    CHEM1111Q5
  1.  
    1. Chlorine gasp1
    2.  
      1. Remove traces of hydrogen chloride gasp1
      2. Drying agentp1
  2. Add 50cm3 of 1.0M sulphuric (VI) acid / Add 25cm3 of 2.0M sulphuric (VI) acid to a beaker containing 50 cm3 of 2M sodium hydroxide and stir.p1 *
    Heat the mixture to saturate while stirring.p1
    Allow slow cooling to form crystals of sodium sulphate.p1                                                         
  3.  
    1. Element E can loss or gain one electron to gain stability hence possible to place it in   group I or group VII. p1
    2.  
      1. Molecular structure. p1
      2. To gain stability/stable configuration. p1
  4.  
    1. Petrol has low carbon hydrogen ratio than diesel hence more flammable. p1
    2. Alkenes and alkynes are more reactive than alkanes hence do not exist naturally. p1
    3. -Manufacture of Tar used in road tarmacking
    4. -Sealing of leakages on roofs.                                  Any correct use p1
  1.  
    1. It neutralizes air to prevent violent combustion reaction from occurring. p1
    2. Its inert and have very low b.pt of -196oC. p1                                                  
  1. -The yellow/orange colour intensifies. P1
    - Adding hydrochloric acid increases concentration of H+ hence favoring backward reaction where more Br2 and H2O are formed. p1
  1. Consider 1000cm3 of the solution
    Mass = 1000 x 1.18
            = 1180g P1/2     
    % acid = 35/100 X 1180P1/2     
     = 413g of acid in 1000cm3 P   
    Molarity= 413/36.5 
    = 11.32MP   
  1.  
    1. To prevent filament from burning out. Provides an atmosphere in which burning cannot occur /provides an inert atmosphere. P
    2. HalogensP
    3. - ZP  1/2     
      - Because its boiling point is above the room temperature. P  1/2   
  2.  
    CHEM111Q14
  1.  
    1. A- Downward delivery /upward displacement of air. P 1/2    
      B – Over water. P 1/2    
    2. A – Denser than airP
  1.  
    1. Soapless detergent P
    2. -Non- biodegradable resulting in pollution P
      - waste a lot of soap during washing before lather is formed.
      - causes stains/blemishes/marks on clothes/garment
      - causes fur on electric appliances like kettle, boilers and pipes form  
  2.  
    chem1111q1777     
  1.  
    1. The rate of diffusion of any gas is inversely proportional to the square root of its density at constants conditions of temperature and pressure. P1
      chem1819999
  1.  
    1. F is place in the middle of the flame while G is placed at the upper region of the flameP1
    2. Non- luminous flameP1
  2.  
    1. Acid …H2O (l) P1/2    
      Base …HSO4- (aq) P1/2    
    2. An acid is a proton donor P1
  3.  
    1. Rhombic or monoclinicü1 Sulphur.
    2. – For hardening rubber
      - Manufacture of sulphuric acid ü1 Any one correct
      - As a fungicide
      - In making calcium hydrogen sulphite used in bleaching.                                                                                            
  4. -The bulb lights P
    - Grey solid deposits at the cathode P
    - Brown gas bubbles produced at the anode P
  5.  
    chem1q4444
  1. -The rate of forward reaction is equal to the rate of forward reaction. P
    - At equilibrium the concentrations of reactants and products do not change. P     
  2.  
    chem1q26666                                                                                                 
  1.  
    1. Contains dissolved NO2 gasP
    2. - A blue solution is formedP
    3. Effervescence of brown gas P
  1.  
    1. Curve IIP
    2.  
      chem1111q2828282828

 

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