Calculate the molecular mass of the following : (i) H2O (ii) CO2 (iii) CH4
i) Molar mass of water (H 2 O) Atomic mass of H=1 Atomic mass of O=16 H 2 O=2×H+1×O Molar mass of water=2×1+16=18g/mol (ii) Molar mass of carbon dioxide (CO 2 ) Atomic mass of C=12 Atomic mass of O=16 CO 2 =1×C+2×O Molar mass of CO 2 =12+2×16=44g/mol (iii) Molar mass of methane (CH 4 ) Atomic mass of C=12 Atomic mass of H=1 CH 4 =1×C+4×H Molar mass of methane=12+4×1=16g/mol
