Question

Calculate the relative molecular masses of Potassium chlorate.

Answer 1

Relative molecular mass of any element or a compound is given by the ratio of its own mass to the mass of one twelfth of the mass of a carbon 12 ( ${{C}^{12}}$ ) atom. Or we can add the relative molecular mass of each element to find the relative molecular mass of the compound.

Complete answer:
Relative molecular mass of any compound is found out by adding the relative molecular mass of its elements. Thus, we will find the sum of relative molecular mass of each element of the compound.
The chemical formula of potassium chlorate is $KCl{{O}_{3}}$, the chemical formula of potassium chlorate consists of one potassium atom, one chlorine atom and three oxygen atoms.
The relative molecular mass of potassium is 39 a.m.u. (atomic mass unit), the relative molecular mass of chlorine is 35.5 a.m.u. and the relative molecular mass of oxygen is 16 a.m.u.
So, now we have to multiply the relative molecular mass of each element with its number of atom and then add them to get the relative molecular mass of the final compound.
As there is only one atom of potassium in the compound, it will be multiplied one. Chlorine also has only one atom in the compound, so it also will be multiplied with one. And there are three atoms of oxygen in the compound, thus it will be multiplied with three.
Thus, $KCl{{O}_{3}}=(1\times 39)+(1\times 35.5)+(3\times 16)$
$KCl{{O}_{3}}=39+35.5+48$
$KCl{{O}_{3}}=125.5$a.m.u.
Thus, the relative molecular mass of potassium chlorate, that is $KCl{{O}_{3}}$, is 125.5 atomic mass units.

Note:
The answer may vary sometimes as the answer written many times has rounded off the relative molecular mass of the elements. Such as, here the relative molecular mass of chlorine is rounded off to 35.5 but its true molecular mass is 35.453.