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INSTRUCTIONS: Answer all the questions in the spaces provided

  1. You are provided with: 

    Potassium manganate ( VII) 
    solution A
    solution B, containing  6.3 g’ litre of dibasic acid H2X.nH2O
    Solution C1 containing 4.0g/litre of  Sodium hydroxide solution.

    You are required to determine :
    1. The value of n in H2X . nH2 O
    2. How the rate of reaction of solution A with solution B varies with change in temperature.

      Procedure 1
      Fill the burette with solution B . Pipette  25cm3 of solution C  into a conical flask and titrate solution B  with Solution C using phenolphthalein indicator.
      Record your results in table below and repeat the titration to obtain consistent results:

      Burette readings




      Final readings (cm3)


      Initial readings (cm3)


      Volume of solution B used (cm3 )

      1. Determine the average volume of solution B used . ( 1mk)
      2. Calculate the concentration of solution C  in moles per litre (Na = 23.0, 16.0, H= 1.0 )   ( 1mk)
      3. Given that the equation of the reaction  taking place  and R.F.M  of X = 88
        H2X (aq) + 2NaOH (aq) → Na2X (aq) + H2O(l)
        1. The number of moles of the dibasic acid solution B that reacted ( 2mks)
        2. The number of moles of the dibasic acid solution B in 1000cm3 of solution. ( 1mk)
        3. The  R.F.M of the dibasic acid, hydrated.   ( 1mk)
        4. The value of n in the formula  of the hydrated acid . ( 0 =16.0  H = 1.0)  ( 2mks)

          Procedure II
          1. Using a measuring cylinder, place  10cm3   portion of solution A  into 5’ test tubes placed in a test tube rack
          2. Clean the measuring cylinder and use it to place 10.0 cm3  of solution B into a boiling tube.
          3. Insert a thermometer in the solution B in the boiling tube and place the boiling  tube  in the attains a temperature of 40o C.
          4. Remove the boiling tube from the water bath and place it in a test- tube rack and add the first portion of solution A. and at the same time start the stopwatch.
          5. Record the time taken for the purple  colour and the mixture to decolourise in table II
          6. Repeat the experiment using 10cm3 of solution B at 50o , 60o c, 70o c  and 80Oc.  Record the time in the table. Complete the table by computing 1h/t  sec-1.

            Temperature of solution B






            Time of colour to decolourise (seconds )

            1/t sec-1






            1. Plot a graph of  1/t  ( sec -1) against temperature.  ( 3mks)
            2. From the graph , determine the time taken for decolourisation of the mixture, if the temperature of solution B was 650C  (1mk)
            3. How does the rate of reaction of potassium manganite (VII) with oxalic acid vary with temperature. ( 1mk)
  2. You are provided with solid Q . Carry out the tests below and record your observations and inferences
    In the spaces provided.
    1. Strongly heat a spatula – end full of solid Q in a dry test – tube.
      1. Place the remaining solid Q  in a boiling tube. Add 10cm3of distilled water. Divide the solution into five portions.
         Observations   Inferences 
                            ½ mk                 ½ mk
      2. To the first portion, add aqueous lead (II) nitrate solution .
         Observations   Inferences 
                          1mk                1mk
      3. To the second portion add dilute nitric (V) acid followed by barium nitrate solution.
         Observations   Inferences 
                          1mk                1mk
      4. To the third portion add a few drops of sodium hydroxide until in excess.
         Observations   Inferences 
                          1mk                1mk
      5. To the fourth portion add few drops of aqueous ammonia until in excess
         Observations   Inferences 
                        ½ mk             ½ mk
      6. To the fifth portion add few drops HCL acid. Warm the content
         Observations   Inferences 
                        ½ mk               ½ mk
  3. You are provided with solid L.  Carry out the tests and your observations and inferences
    1. Place about one third of solid L on a metallic spatula and burn it using Bunsen burner.
       Observations   Inferences 
                      ½ mk               ½ mk
    2. Place the remaining solid L in a test tube Add about 6cm3 of distilled water and shake well. Retain the mixture for use in tests (C)
       Observations   Inferences 
                      ½ mk               ½ mk
      1. To about 2cm3 of te mixture add a small amount of sodium hydrogen carbonate.
         Observations   Inferences 
                          1mk                1mk
      2. To about  1cm3 of the mixture add 1cm3 of acidified potassium dichromate (VI) and warm
         Observations   Inferences 
                          1mk                1mk
      3. To about 2cm3 of the mixture  add two drops acidified potassium manganite (VII)
         Observations   Inferences 
                          1mk                1mk


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