Behs larpoh

in chem •  last year 
  1. Answer any FOUR questions. (32 marks)
    (a) (i) Define buffer solution.
    (ii) Calculate the pOH of a buffer solution containing 0.2 mole of ethanoic acid (pKa=3.8) and 0.05 mole
    of sodium ethanoate per 200 cm3 of solution.
    (b) (i) Define the electrical energy and the mechanical energy.
    (ii) Calculate the heat of combustion of butane gas (C4H10) if its heat of formation is -124 kJ mol-1.The
    Heats of formation of CO2 (g) and H2O(l) are -395 kJ mol-1 and -287 kJ mol-1, respectively.
    (c) Write down the complete equations of the following equations.
    (i) CH3-CH2-COONa + NaOH → ?

        (iii) CH3-CH2-OH         Al2O3         ?
    
        (iv) CH3-CH2-Cl   + KOH       ethanol        ?
    

    (d) (i)What happens when ozonized oxygen is passed into ethane in chloroform and the product is
    decomposed by water?
    (ii) What happens when propene is passed into cold dilute potassium permanganate solution?
    (iii) What happens when addition of hydrogen bromide to propene.
    (iv) What happens when ethyl chloride is heated with alcoholic solution of KOH.
    (e) Give an account on the manufacture of sodium by Down process.
    (f) Describe the laboratory preparation of iodine with a suitable diagram.
    (g) 6.5 g of a mixture of sodium chloride and anhydrous sodium carbonate were made up to 500 cm3 of
    aqueous solution. 25cm3 of this solution required 20 cm3 of 0.104M sulphuric acid for neutralization.
    Calculate the percentage by mass of sodium chloride in the mixture.(C =12,O =16,Na =32).
    (h) Discuss the extraction of lead

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