Question

Calculate the relative molecular mass of
the following:
(a) H₂O
(b) HNO3
(c) Cacl2​

Answer 1

H2o

= For H2O molecule -

Relative mass of hydrogen (H) = 1u.

Relative mass of oxygen (O) = 16u.

According to the formula of water contains 2 hydrogen atoms,

5.So, relative mass of water = 2 *( 1u ) + 16u. = 18u.

6.So, Relative mass of water = 18u.

HNO3

=The molar mass of the chemical substance is equal to the sum of the atomic mass of the individual atoms. (1 × 1) +(1 × 14) + (16×3) = 63 u.

cacl2

= Molecular formula is CaCl2 i.e. 1 atom of Ca and 2 atoms of Cl . Hence, molecular weight = 1 x 40 + 2 x 35.5 = 40 + 71 = 111 g / mol