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2015-04-10T17:30:01+05:30

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1)  water : 18 gm / mole = 6.023 * 10^23 molecules / mole
             =  18 ml /mole  =>  1 ml contains 6.023 * 10^23 / 18  molecules

2)  total number of protons in one molecule = atomic numbers = 20+6+8 * 3 = 50
       total molecular weight of Calcium carbonate = 100
     number of protons = 50 * 6.023 * 10^23 * 10 gm/100 gm

3)  33.6litres of O2 at STP consists of  33.6/22.4 = 1.5 moles = 48 gms
       in one molecule of potassium chlorate 3 atoms = 1.5 moles of oxygen.
         so we need 1.5 moles of O2 => 1 mole of KCLO3 => 122.5 gms

4)  C6 H6 :  mass of H : 6      mass of C:  6*12 = 72
       % composition of H :  6/(72 + 6) = 7.7%        %f of C : 92.3%

5)  HCl :  36.5 gm/mole           H2 SO4 : 98 gm/mole
         there are 2 ions per HCl molecule and 3 ions per molecule of H2SO4.
     ions: [ 2 * 9.125 gm/ 36.5 gm/mole * 3 * 73.5 gm / 98 gm/mole ] 6.023 * 10^23 molecules/mole

6)  atomic mass =  6.023 * 10^23 * 13.8 gms / [4.6 * 10^22 ] = 180.69

7)      2  NH3 :  N2 + 3 H2
           1 moles of N2 gives 2 moles of ammmonia.
           2.8 gms of N2 = 2.8 / 28 moles = 0.1 moles
               so 0.1 moles gives 0.2 moles of ammonia. For this  0.3 moles of H2 are needed.    0.3 moles at NTP occupy  22.4 * 0.3 litres

8)
       2 C H I3 + 3 Ag =   C2 H2 + 6 Ag I
         produces acetylene or ethyne and Silver Iodide precipitate Yellow color.
           Acetylene gas produced is = 1/2 * 0.01 mole = 0.005 moles
           so its volume at NTP = 22.4 * 0.005 = 0.112 litres  = 112 ml
            
9)  3 Na OH + H3 PO4  =>  Na3 PO4 + 3 H2 O
             9.8 gms of acid =>  1/10 moles  as  its molecular weight is 98
    so need 0.3 moles of sodium hydroxide.        that is 0.3 * 40 gms

10)  4  Al + 3 O2 ==> 2 Al2 O3
         27 grams of Al => 1 mole.  so  it reacts with 3/4 moles of O2 = 24 grams

11)  2 Ag2 CO3 + O2 => 2 Ag2 O + 2 CO2
         276 gms of silver carbonate is 1 mole => we have 0.01 moles.
           residue  Ag2 O  has 232 molecular weight.
       so 0.01 moles will give rise to 0.01 moles of silver oxide, which is 2.32 gms

12)    Co2 has 44 molecular weight.    limestone : Ca CO3 => Ca O + CO2
             84 gm of Ca Co3  is one mole  that gives 1 mole of CO2 ie., 44 gms
                 2 gm of  calcium carbonate limestone is calcined then we get
                       44/84 * 2 gms.


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