Chemistry Paper 2 Questions - Maranda High School Mock Exams 2023

Instructions to candidates

• Answer all the questions in the spaces provided in the question paper.
• KNEC mathematical tables and electronic calculators may be used for calculations.
• All workings MUST be clearly shown where necessary.
• Candidates should answer the questions in English.

1.  
   1. A student used the set up below to investigate the action of dilute sulphuric (VI) acid on some metals. Beaker I and Beaker II contained equal volumes of dilute sulphuric (VI).To beaker I, a clean Iron rod was dipped and to beaker II ,a clean copper rod was dipped.
                
      1. Why was it necessary to clean the metal rod (1 mark)
      2. State the observation made in each case
         1. Beaker I (1 mark)
         2. Beaker II (1 mark) ………………………………………………………………………………………………………
      3. Explain the observation in (a) (ii) (2 marks)
   2. When 0.65g of Zinc was reacted with excess dilute hydrochloric acid at room temperature and pressure, an exact volume of hydrogen gas was collected. (Zn=65.0; Molar gas volume=24.0dm³)
      1. Draw a diagram of the apparatus used to carry out the experiment described above (2marks)
      2. Write the equation of the reaction (1 mark) 
      3. Calculate the volume of hydrogen gas produced in cm3    (2 marks)
      4. Calculate the volume of 0.25 M hydrochloric acid required to react with 0.65g of Zinc     (3 marks)
2. The flow chart below shows reactions of some organic compound
   
   1. Write the formula and give the names of compounds
      1. Q (2 marks)
         Name ………………………………………………………………………………………………
         Formula……………………………………………………………………………………………...
      2. R (2 marks)
         Name………………………………………………………………………...………………………
         Formula…………………………………………………………………………………………...
   2. Give reagents and conditions necessary for carrying out
      1. Step 3 (1 mark)
      2. Step 5 (1 mark)
   3. Step 1 can be carried out using concentrated Sulphuric (VI) acid and heat. Name another reagent and conditions that can be used to carry out step 1 (1 mark)
   4. Give the name of the type of reaction taking place in
      1. Step 1 (1 mark)
      2. Step 5 (1 mark)
   5.  
      1. Write an equation for the reaction in step 6 (1 mark)
      2. State the observation made in step 6 (1 mark)
3. In an experiment to investigate the enthalpy of reaction between excess magnesium and dilute hydrochloric acid,50.0 cm³ of 2.0M HCl was placed in a plastic beaker .The temperature of the solution was recorded after every 30 seconds. At exactly two minutes, excess magnesium granules were added and temperature of the mixture recorded every 30 seconds for additional four minutes .The results was recorded in the table below.
   

   Time (sec)	0	30	60	90	120	150	180	210	240	270	300
   Temp °C	22.0	22.0	22.0	22,0	x	25.0	27.0	29.0	29.0	28.0	27.0

   1. Plot a graph of temperature (°C) against time (sec) (3 marks)
   2. From the graph determine the highest temperature change (1 mark)
   3. Calculate:
      1. The amount of heat given out during the reaction (C=4.2J/g/K,density of the solution =1g/cm³)     (1 mark)
      2. The molar heat of reaction (2 marks)
   4. Some average bond energies are given below.
      

      Bond	Energy in kJ/mol
      C-C	348
      C-H	414
      Cl-Cl	243
      H-Cl	340
      C-Cl	432

      Determine whether the reaction below is exothermic or endothermic. (3marks)
      C₂H_6(g) + Cl_2(g) → C₂H₅Cl_(g) + HCl_(g)
4.  
   1. Use the reduction potential give below to answer the questions that follow. The letters are not the actual symbols of the elements.
      

      Reaction	EƟ value(V)
      Q2+(aq) + 2e− → Q(s)	−0.86
      C+(aq) + e− → ½C2(g)	0.00
      D2+(aq) + 2e− → D(s)	+0.34
      R2+(aq) + 2e− →R(s)	−0.44
      A2(g) + 2e− → 2A−(aq)	+1.09

      1. Identify the strongest oxidizing agent. Explain (2 marks)
      2. State and explain the element which can be used as reference cell (2 marks)
      3. Draw and label an electrochemical cell that can be constructed from element A and Q .Show the direction of electron flow. (3 marks)
      4. Show if it would be possible to store a solution containing ions of D in a container made of R? (2 marks)
      5. State any two standard conditions of an electrochemical cell (1 mark)
   2. The set up below shows a cell used to electrolyze water
      
      1. State why it is necessary to add dilute sulphuric (VI) to water (1 mark)
      2. State the electrode at which oxygen is produced and give a reason (1 mark)
      3. Write an equation for the formation of oxygen (1 mark)
5.  
   1. State Le Chatelier’s principle (1 mark)
   2. State and explain how a catalyst affects:
      1. Rate of reaction (2 marks)
      2. Yield of the product (1 mark)
   3. One of the reactions in the manufacture of nitric (V) acid involves catalytic oxidation of ammonia as shown in the equation below.
      4 NH3(g) +5O2 (g) 4NO(g) + 6H2O(g) ; ∆H= –909 kJ mol–1
      The reaction is carried out at a pressure of 9 atmospheres and a temperature of 900°C
      1. State and explain the effect on the position of equilibrium if the reaction is carried out:
         1. At 9 atmospheres and 500°C ; (2 marks)
         2. . At 900°C and 15 atmospheres pressure; (2 marks)
   4. State and explain the effect on the rate of the reaction if the reaction is carried out at 9 atmosphere and 450°C (2 marks)
6. The grid below represents part of the periodic table. Use it to answer the questions that follow.
   
   1.  Place each of the following in the grid above.
      1. Element A, whose atomic number is 10 (1 mark)
      2. Element Q, which forms a chloride that is used in lowering melting point in extraction of sodium metal. (1 mark)
      3. Element Z, a metal which forms a chloride that dissolves in water to form a solution with a pH of about 2 (1 mark)
      4. Element E, a period 3 element which forms a soluble carbonate (1 mark)
      5. Element X, a halogen with the largest atomic radius (1 mark)
      6. Element G, a non-metal the with highest electron affinity (1 mark)
      7. Element Y, a period 3 element with the largest atomic radius (1 mark)
      8. Element P, the most electropositive element (1 mark)
   2. Give the total number of elements that can be placed in
      1. Period 1 (½ mark)
      2. Period 4 (½ mark)
   3. Zinc and carbon form oxides with general formula YO. Complete the table below writing the properties of the oxides (3 marks)
      

      Property	ZnO	CO
      Nature
      Bonding
      Strcuture

7.  
   1. The flow chart below shows an analysis of a mixture R that contains two salts .Study the analysis and answer the questions that follows.
      
      1. State:-
         1. .The condition in step I (1 mark)
         2. The process in step II (1 mark)
      2. Small portion of mixture R is added to dilute Nitric (VI) acid in a boiling tube. What would be observed (1 mark)
      3. Write an equation for the reaction between cation in filtrate X and excess Ammonia solution.    (1 mark)
      4. Explain how water vapour in step (iv) could be identified (2 marks)
      5. Identify filtrate X (1 mark)
   2. Study the flow chart below and answer the questions that follow.
      
      1. State and explain the conclusion that can be made in step VI only (1 mark)
      2. Name anion present in residue U (1 mark)
      3. From the flow chart in (a) and (b); write the formulae of the cations present in mixture R   (2 marks)