Question

The molar mass of fluorine is 19.00 g/mol and that of aluminium is 26.98 g/mol. How do you calculate the molar mass of aluminium fluoride?

Answer 1

As we know that molar mass of a chemical compound is the weight of one mole of an element or of a chemical compound. We can calculate the molar mass of a compound by adding the individual atomic masses of all the elements present in the compound.

Complete step by step answer:
- The required molar mass of a given compound can be calculated by dividing the mass of a given chemical compound or element divided by the number of moles of the substance.
- We can also find the molar mass of an element or chemical compound from the atomic masses of all the atoms in the molecule by just adding the individual atomic masses of all the elements.
- To find the molar mass in case of the multiple atoms of the same element in a compound, multiply the number of atoms with the atomic mass of the element and then add to the atomic masses of other elements.
- Let’s calculate the molar mass of aluminium fluoride:
As we know that the formula of aluminium fluoride is$Al{{F}_{3}}$ . We can see here that one formula unit contains three atoms of F and one atom of Al. We can calculate the molar mass of aluminium fluoride$Al{{F}_{3}}$ as:
$\begin{aligned} & Mass\text{ }of\text{ 1 mol= 1mol Al }\times \dfrac{26.98}{1\text{ }mol\text{ }Al}+3\text{ mol F}\times \dfrac{19g}{1\text{ }mol\text{ }F} \\\ & =26.98g+57.00g \\\ & =83.98g \\\ \end{aligned}$
- Hence, in this way we can calculate the molar mass of aluminium fluoride and get the answer as 83.98 g.

Note: It should be noted that when we are calculating the molar mass, be careful to multiply the number of atoms of the element with its atomic mass. If we will not do so, then it will result in an incorrect answer.