Chemistry Paper 2 Questions and Answers - Asumbi Girls Mock Examinations 2022

Share via Whatsapp

QUESTIONS

  1. The diagram shows part of the Periodic Table. The letters are not the actual symbols of the elements.
    1
    1. Compare the reactivity between elements Q and T. (2 marks)
    2. Explain the electrical conductivity of the chloride of element T. (2 marks)
    3. Compare the melting and boiling points of elements R and S. (2 marks)
    4. Write an equation for the second ionization energy of element Q. (1mark)
    5. How does the atomic and ionic radius of each of the following elements compare?
      1. Element T. (1½ marks)
      2. Element P (1½ marks)
    6. Compare atomic radius of elements R and Q. (1½ marks)
    7. Explain the difference in the melting points of the oxides of element Q and the oxide of element R. (1½ marks)
  2.      
    1. The diagram below shows the structure of an allotrope of sulphur
      2
      1. What are allotropes? (1mark)
      2. Identify the allotrope shown in the diagram above. (1mark)
      3. State two properties of the allotrope above. (2 marks)
    2. Study the flow chart below and answer the questions that follow.
      3
      1. Write the equation for the reactions in:
        1. step I. (1mark)
        2. Step II. (1mark)
      2. State two observations made in step II. (2 marks)
      3. Explain the observations made in:
        1. Step IV. (1½ marks)
        2. Step V. (1½ marks)
      4. State one use of gas T. (1mark)
  3. Next to each letter, A to F, in the table below is the molecular formula of an organic compound. 
    4
    1. Choose a molecular formula above that represents an organic compound below. Write down only the letter (A to F) next to the question numbers 
      1. A haloalkane (½ mark)
      2. An alcohol (½ mark)
      3. An unsaturated hydrocarbon (½ mark)
      4. A product of thermal cracking of compound C. (½ mark)
    2. If compound F is a carboxylic acid, write down the following:
      1. The structural formula of a functional isomer (an isomer with a different functional group) of F. (1mark)
      2. The IUPAC name of a functional isomer of F. (1mark)
    3. Compound B is a monomer used to make a polymer. Write down the:
      1. Definition of a polymer. (1mark)
      2. IUPAC name of the polymer. (1mark)
      3. Balanced equation for the polymerisation reaction (1mark)
    4. Compound A is used as a reactant in the production of compound D. 
      1. Name the type of reaction that takes place. (1mark)
      2. State two changes that can be made to the reaction conditions in (d) (i) to obtain compound B, instead of D, as product. (2 marks)
  4. The flow chart below summarizes the extraction of Zinc, study it and answer the questions that follow.
    5
    1. Name the process represented by A and B
    2. Identify the reagents required for process B, C and D (3 marks)
    3. Write a chemical equation of the reaction that occurs in process B (1mark)
    4. With an aid of a diagram, explain how you would obtain a pure sample of Zinc by process E. (2 marks)
    5. State two uses of Zinc metal (2 marks)
  5.      
    1. The table below gives some values of standard enthalpies of formation (ΔHfƟ).
      Substance F2(g)  CF4(g)  HF(g)
      ΔHfƟ (kJmole-1) 0 -680 -269
      The enthalpy change for the reaction C2H6(g) + 7F2(g) → 2CF4(g) + 6HF(g) is –2889 kJ mol–1
      Use this value and the standard enthalpies of formation in Table 2 to calculate the standard enthalpy of formation of C2H6(g). (3 marks)
    2. In an experiment to determine the enthalpy of solution of concentrated sulphuric (VI) acid (specific gravity = 1.84gcm-3) the following procedure was used: 
      • A clean 250.0 cm3 glass or plastic beaker is wrapped with a newspaper leaf.
      • About 50.0 cm3 of tap water is measured into the beaker and the steady temperature noted.
      • The beaker is held in a tilted position and 2.0 cm3 of and sulphuric acid added into the water
        1. Why was the beaker wrapped with newspaper leaf?  (1mark)
        2. Why was the acid added into water and not vice versa? (1mark)
        3. Explain the reason for tilting the beaker during addition of the acid into water. (2 marks)
        4. Calculate the molar enthalpy of solution of concentrated sulphuric (VI) acid given that ∆T for the reaction = 1ºC. (Density of water = 1gcm-3; specific heat capacity of water = 4.2kJkg-1K-1).      (4 marks)
  6.      
    1. Consider the electrochemical cell represented by the cell notation below, where X is an unknown metal:
      Pt(s) | Fe2+(aq), Fe3+(aq) || X+(aq) | X(s)
      (The cell potential of this cell was found to be 0.03 V.
      1. Write down the type of electrochemical cell illustrated above. (1mark)
      2. What does the single line (|) in the above cell notation represent? (1mark)
      3. Write down the half-reaction that takes place at the anode in the above cell. (1mark)
      4. Given that:
         Half reaction EƟ (volts)
        Fe3+(aq) + e → Fe2+(aq) +0.77
        Ag+(aq) + e → Ag(s) +0.80
        Na+(aq) + e → Na(s)  -2.87
        K+(aq) + e → K(s)  -2.92
        Identify X with the aid of a calculation. (2 marks)
    2. The diagram below shows the apparatus that can be used to electrolyse dilute Sulphuric acid. Study it to answer the questions that follow. 
      6
      1. Identify the gases H and G 
        1. H (1mark) 
        2. G (1mark) 
      2. What happens to the concentration of the Sulphuric acid during the process with time? Explain (2 marks) 
      3. During the electrolysis a current of 0.72A was passed through the electrolyte for 15 minutes. Calculate the volume of gas H produced. (1 Faraday = 96,50ºC, molar gas volume = 24 dm3 at r.t.p). (3 marks) 
  7.      
    1.       
      1. What is a salt? (1mark)
      2. Write the formula of any two double salts. (1mark)
    2. A student has found that her sample of potassium nitrate is contaminated with small amounts of a green solid. She picks out a small piece of the green solid and finds that it is insoluble in water.
      1. Describe how you would make a pure sample of potassium nitrate from the impure mixture. (3 marks)
      2. The student believes that the green solid is copper (II) carbonate. Describe a series of 3 tests that the student could use to confirm this. (6 marks)
        Test Procedure Observations Conclusions
        1      
             
             
    3. In an experiment 50g of a saturated solution of a salt X was heated to dryness in an evaporating dish. The mass of crystals when weighed gave a reading of 2.7g. Determine the solubility of the salt. (2 marks)


MARKING SCHEME

  1.      
    1. T is more reactive than Q; T has more energy levels than Q hence larger atomic radius; the valence electrons in T are less strongly attracted to the nucleus hence easier to lose;
      Owtte
    2. Cannot conduct in solid state, but can conduct in solution and molten states; T has giant ionic structure; in solid state the ions are held in the crystal lattice; in solution and molten states, the ions are free and mobile for electrical conductivity;
    3. R has higher melting and boiling points than S; both have molecular structures; but R ahs larger molecules than S; hence more van der waals forces which need more heat to break (compared to S);
    4. Q+(g) → Q2+(g) + e;
    5.    
      1. Atomic radius of T is larger than its ionic radius; T forms ions by losing electrons; leading to lose of an entire energy level; hence ions have fewer energy levels than  atoms;
      2. Atomic radius of P is smaller than the ionic radius; P ionizes by gaining electrons hence increased electron-electron repulsion;
    6. Element Q has a larger atomic radius than R; for the same number of energy levels R has more protons than Q hence a stronger effective nuclear pull of valence electrons towards the nucleus;
    7. Oxide of Q has a higher MP and BP than the oxide of R; Q oxide has a giant ionic structure with strong ionic bonds which require more heat to break; R has a simple molecular structure; with weak van deer waals forces which require less heat to break;
  2.        
    1.      
      1. Different crystalline forms of then same element in the same physical state;
      2. Monoclinic sulphur;
      3.      
        • Prismatic / hexagonal in shape;
        • Stable above 96ºC;
        • Needle-like in shape;
        • Pale yellow in colour;
        • Has a melting point of 119ºC;
        • Has a density of 1.98g/cm3;
    2.    
      1.      
        1. S(s) + Fe(s) → FeS(s);
          Heat must be on the arrow
        2. FeS(s) + 2HCl(aq) → FeCl2(aq) + H2S(g);
      2. Formation of a green solution;
        Colourless gas with a rotten egg smell;
      3.    
        1. Brown fumes; yellow deposits; H2S is oxidized to sulphur; HNO3 is reduced to NOand H2O;
        2. Yellow solution changes tom a green solution, yellow solid // suspension; H2S reduces Fe3+ to Fe2+; while H2S is reduced to S;
      4. Production of sulphur and sulhuric (VI) acid;
        Create inorganic sulphides for the manufacture of pharmaceuticals, pesticides, leather, dyes etc
  3.           
    1.       
      1.  A;
      2. D;
      3. B;
      4. B;
    2.    
      1. Structural functional isomer
        7
        Mark whole structure
      2. Any one of:
        Methyl ethanoate;
        OR
        Ethylmethanoate;
    3.      
      1. A large molecule composed of smaller monomer units covalently bonded to each other in a repeating pattern;
      2. Polyethene;
        Accept Polyethylene/polythene
      3. Equation
        8
    4.      
      1. Hydrolysis/Substitution;
      2. Use concentrated strong base / NaOH / KOH / LiOH OR ethanolic / alcoholic strong base / NaOH / KOH / LiOH. / Use ethanol instead of water. / No water.
        Heat strongly;
        Accept: Increase temperature;
  4.      
    1. A – Roasting;
      B – Reduction;
    2. B – C/ Coke;
      C – H2SO4(aq) / Dilute sulphuric VI acid;
      D – Dilute H2SO4;
    3. ZnO(s) + C(s) → Zn(s) + CO(g) 
    4. Diagrams
      9
      • Dip Zinc rods in a solution of ZnSO4(aq);
      • Complete circuit where anode dissolves (impure Zinc) and pure Zinc is discharged at the cathode;
    5.    
      • Cases in dry cells;
      • Galvanizing iron sheets;
      • Making alloys (Brass i.e. copper and Zinc)
        Any two) 
  5.      
    1. Calculation
      ΔH = Σ ΔfH products – Σ ΔfH reactants or a correct cycle
      Hence = (2 × –680) + (6 × –269) – (x) = –2889
      x = 2889 – 1360 – 1614 = –85 (kJ mol–1)
    2.      
      1. To reduce heat loss to the surrounding; 
        Reject to stop // prevent heat loss;
      2. Addition of acid into water will lead to an exothermic reaction; the heat energy evolved would cause vapourization of the acid which may cause acid burns; adding acid to water ensures the denser acid sinks to the bottom of the container so that no surface vapourization (which may be dangerous) occurs;
        Owtte;
      3. Avoid spurting of the acid;
        Ensure the acid sinks faster to the bottom of the container;
      4. ∆H = MC∆T;
        Total volume = 50 cm3 + 2cm-3 = 52cm3;
        Note: addition of liquid into a liquid causes a change in volume;
        Mass = 52 cm3 x 1gcm-3 = 52g = 0.051kg;
        Heat change = 0.052 x 4.2 x 1;
                             =- 0.2184 kJ;
        Mass of sulphuric acid = 2 x 1.84 = 3.68g;
        Thus 3.68g = -0.2184 kJ;
        Then 98g = 98 x 0.2184 = -5.8085 kJ per mole;
                                3.68
        Penalize ½ mark for wrong or missing sign // SI unit;
  6.      
    1.    
      1. Galvanic (cell)/Voltaic (cell);
      2. Indicates phase boundary / Interphase / phase separator;
      3. Fe2+(aq) → Fe3+(aq) + e-;
      4. Calculation:
        EƟ = EƟreduction – EƟoxidation
        0.03V = EƟreduction  – 0.77
        EƟreduction  = 0.03 + 0.77
                  = + 0.80V
        Thus X is silver;
        Accept any other correct formula.
    2.    
      1. Solution or a melt that allow current to pass through and is decomposed. √1
      2.      
        1. G: Oxygen gas;
        2. H: Hydrogen gas;
      3. Concentration increases because OH- ions and H+ ions are discharged; hence continuous dissciationofwaterr from the electrolyte;
      4. Calculation
        2H+(aq) + 2e → H2(g)
        Q = 0.72 x 15 x 6ºC.
            = 738C;
        2 x 96,50ºC → 24dm3 
        738C → 24 x 738 dm3
                       193,000
        = 0.0918dm3 (91.8cm3)
  7.      
    1.      
      1. A substance formed when a cation from an alkali reacts with an anion from an acid;
      2. (KAl(SO4)2.12H2O;
        [Fe(NH4)2(SO4).6H2O;
        Na2CO3.NaHCO3.2H2O;
    2.    
      1.      
        • Add water to the mixture and stir;
        • Filter to obtain potassium nitrate solution as the filtrate;
        • Heat the filtrate until saturated;
        • Allow saturated solution to cool and crystallize;
        • Pour off the mother liquor;
        • Dry the crystals between filter papers;
      2. Series of tests
        Test Procedure Observations Conclusions
        1 To the green solid add drops of dilute nitric (V) acid / hydrochloric acid / sulphuric (VI) acid; Effervescence of a colourless odourles gass that extinguishes a glowing splint;  Production of carbon (IV) oxide confirms presence of carbonate 
        To a sample of the solution from test 1 add aqueous sodium hydroxide dropwise till in excess  Blue nprecipitate that is insoluble in excess;
         
        Formation of copper (II) hydroxide which is blue in colour; 
        3 To a sample / portion of solution from test 1 add drops of aqueous ammonia dropwise till in excess Blue precipitate soluble in excess to form a deep blue solution; Formation of blue copper (II) hydroxide with little ammonia which dissolves in excess ammonia to form a deep blue solution of tetra amine copper (II) ions;
    3. Calculation:
      Mass of solvent: 50 – 2.7 = 47.3g
      Thus if 47.3g → 2.7g of salt
      Then 100g → 100 x 2.7 = 5.7082g/100g of solvet;
                                47.3

Download Chemistry Paper 2 Questions and Answers - Asumbi Girls Mock Examinations 2022.


Tap Here to Download for 50/-




Why download?

  • ✔ To read offline at any time.
  • ✔ To Print at your convenience
  • ✔ Share Easily with Friends / Students


Join our whatsapp group for latest updates
.
Subscribe now

access all the content at an affordable rate
or
Buy any individual paper or notes as a pdf via MPESA
and get it sent to you via WhatsApp

 

What does our community say about us?