Friday 29 June 2012

Calculate the molecular mass of the following : (i) H2O (ii) CO2 (iii) CH4

 Calculate the molecular mass of the following : (i) H2O (ii) CO2 (iii) CH4
Method -1
(i)Molecular mass of H2O=2 × Atomic Mass of H+Atomic Mass of O=2+16=18 a.m.u
(i)Molecular mass of CO2 =Atomic Mass of C+2 × Atomic Mass of O=12+32=44 a.m.u
(i)Molecular mass of CH4 =Atomic Mass of C+4 × Atomic Mass of H=12+4=16 a.m.u
Method -2
(i) H2O:
The molecular mass of water, H2O
= (2 × Atomic mass of hydrogen) + (1 × Atomic mass of oxygen)
= [2(1.0084) + 1(16.00 u)]
= 2.016 u + 16.00 u
= 18.016
= 18.02 u
(ii) CO2:
The molecular mass of carbon dioxide, CO2
= (1 × Atomic mass of carbon) + (2 × Atomic mass of oxygen)
= [1(12.011 u) + 2 (16.00 u)]
= 12.011 u + 32.00 u
= 44.01 u
(iii) CH4:
The molecular mass of methane, CH4
= (1 × Atomic mass of carbon) + (4 × Atomic mass of hydrogen)
= [1(12.011 u) + 4 (1.008 u)]
= 12.011 u + 4.032 u
= 16.043 u
 

22 comments:

  1. Decimal ke waad wale number kha se ate hai

    ReplyDelete
    Replies
    1. They are the full atomic mass of the given elements.

      Delete
  2. Sir...molar and molecular mass samemail hota h kya?

    ReplyDelete
  3. First method smaj nhi aayi mujhe
    2×atomic mass of h +atomic mass of o
    =2+16
    But formula Ka 2 Kahan Gaya yei toh multiple huva he nhii

    ReplyDelete
    Replies
    1. 2 multiple kisliye hoga yaha to bs 1 carbon h n

      Delete
    2. Hydrogen Ka atomic mass 1 hota hai or 2×1=2 hota hai

      Delete