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



Q.1 :- Calculate the molecular mass of the following :

(i) H2O  (ii) CO2  (iii) CH4

 

Answer:-



(i) H2O = (2×Atomic mass of H) + (1×Atomic mass of O)
= [2(1.0084) + 1(16.00)] amu = 2.016 u + 16.00 amu = 18.016 amu
(ii) CO2 = (1 × Atomic mass of C) + (2 × Atomic mass of O)
= [1(12.011) + 2 (16.00)] amu = 12.011 amu + 32.00 u = 44.01 amu
(iii) CH= (1 × Atomic mass of carbon) + (4 × Atomic mass of hydrogen)
= [1(12.011) + 4 (1.008)] amu = 12.011 amu + 4.032 amu = 16.043 amu