Question

The molecular mass of $CuS{O_4}.5{H_2}O$ is:
(Atomic mass of $Cu = 63.5,H = 1,O = 16,S = 32$)
$\left( A \right)$ $233.5gm/mol$
$\left( B \right)$ $249.5gm/mol$
$\left( C \right)$ $251.5gm/mol$
$\left( D \right)$ $247.5gm/mol$

Answer 1

Molecular mass of a molecule is defined as the mass of molecules that is equal to the sum or addition of the masses of all the atoms that are present in the given molecules. It is expressed in $gm/mol$ .

Complete step by step answer:
In the given question we have asked to calculate the molecular mass of $CuS{O_4}.5{H_2}O$can be determined by adding masses of all atoms that are present in the$CuS{O_4}.5{H_2}O$molecules. In $CuS{O_4}.5{H_2}O$ four different atoms are present and the mass of these atoms are given in the question. Out of four atoms there are one copper $\left( {Cu} \right)$ , one sulphur $\left( S \right)$ , nine oxygen$\left( O \right)$ and ten hydrogen $\left( H \right)$
So, the molecular $CuS{O_4}.5{H_2}O = [{\text{Atomic mass of copper + Atomic mass of sulphur + }} {{ 5}} \times {\text{Atomic mass of oxygen + }} {{10}} \times {\text{Atomic mass of hydrogen}}]$
$\Rightarrow$ Molecular mass of $CuS{O_4}.5{H_2}O = \left[ {63.5 + 32 + 9 \times 16 + 10 \times 1} \right]$
$\Rightarrow$ Molecular mass of $CuS{O_4}.5{H_2}O = 249.5gm/mol$
Thus, the molecular mass of $CuS{O_4}.5{H_2}O$ is $249.5gm/mol.$
So , the option $\left( B \right)$ is correct .

Additional information: Copper sulfate pentahydrate is an inorganic compound with the chemical formula $CuS{O_4}.5{H_2}O$ . It is blue solid in blue colour. These are solid crystalline. $CuS{O_4}.5{H_2}O$ is decomposed when heated and given anhydrous copper sulfate. The older name of this compound includes blue vitriol, bluestone and Roman vitriol.
It is used as a fungicide. However some fungi are capable of adapting to elevated levels of copper ions.
A suspension of copper sulfate and calcium hydroxide is used to control fungus on grapes, melon and other berries.
A mixture of copper sulfate and ammonium carbonate is used in horticulture to prevent damping of seedlings.

Note:
The molecular mass is the mass of a given molecule, it is measured in Dalton. Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element.