Question

What is the molecular mass of Sodium Sulphate?
A.154
B.119
C.165
D.142

Answer 1

The molecular formula of Sodium Sulphate is $N{a_2}S{O_4}$ . So, to calculate its molecular mass, the atomic mass of its atoms is added. The atomic mass of Na is 23, S is 32 and O is 16 and we have 2 atoms of Na, 1 atom of S and 4 atoms of O.

Complete step by step answer:
-The molecular mass of a compound is defined as the sum of the atomic masses of all atoms in a molecule.
-Sodium Sulphate, a white crystalline solid is a sodium salt of sulphuric acid. It is used in Kraft process of paper pulping, as a fining agent in glass making, in home detergents as a filler, to dry organic liquid.
-Sodium Sulphate consists of 2 atoms of Sodium, 1 atom of Sulphur and 4 atoms of Oxygen. The molecular formula of sodium sulphate is $N{a_2}S{O_4}$
The atomic mass of Sodium (Na) is 23
The atomic mass of Sulphur (S) is 32
The atomic mass of Oxygen (O) is 16
Therefore, the molecular mass of sodium sulphate $N{a_2}S{O_4}$ is
$= \left( {2 \times 23} \right) + 32 + \left( {4 \times 16} \right)$
= 46 + 32 + 64
=142g/mol
The molecular mass of sodium sulphate is $(N{a_2}S{O_4})$ 142.

So, the correct answer is option (D).

Note:
Simply to calculate the molecular formula, the atomic mass of each atom in a molecule is added. Sodium (Na) is the sixth most abundant element in the earth’s crust. Sodium sulphate bearing mineral deposits are geologically young which are mainly of post glacial age. Natural sodium sulphate is produced from naturally occurring brines and crystalline deposits. The density of sodium sulphate is 2.65 $\dfrac{{gm}}{{c{m^3}}}$ . Its boiling point and melting point is $884^\circ C$. It is soluble in water.