Question

Calculate the molecular mass of the following:
(i) $H_{2}O$
(ii) $CO_{2}$
(iii) $CH_{4}$

Answer 1

The atomic mass of some of the elements as required by the question:
H = 1 amu, O = 16 amu, C = 12 amu

Now,
( i ) $H_{2}O$
Molecular mass of $H_{2}O$ = ( 1 * 2 ) + 16
Molecular mass of $H_{2}O$ = 2 + 16
Molecular mass of $H_{2}O$ = 18 amu

( ii ) $CO_{2}$
Molecular mass of $CO_{2}$ = 12 + ( 16 * 2 )
Molecular mass of $CO_{2}$ = 12 + 32
Molecular mass of $CO_{2}$ = 44 amu

( iii ) $CH_{4}$
Molecular mass of $CH_{4}$ = 12 + ( 1 * 4 )
Molecular mass of $CH_{4}$ = 12 + 4
Molecular mass of $CH_{4}$ = 16 amu