Question

How many moles of $Cl$ are in 2.7 mol$CaC{{l}_{2}}$?

Answer 1

A chemical compound has a definite amount of each of its elements in a fixed ratio. This is also called the law of constant proportion. Stoichiometric factors are used in obtaining an unknown quantity from the given quantity.

Complete answer:
Calcium and chlorine react with each other to form calcium chloride. The reaction is:
$Ca+C{{l}_{2}}\to CaC{{l}_{2}}$
Through this we can know that 1 mole of calcium and 2 moles of chlorine is used to produce 1 mole of calcium chloride. We have to look on the relation between chlorine and calcium chloride, which can be written in terms of conversion factors as:
$\dfrac{2\,mol\,Cl}{1\,mol\,CaC{{l}_{2}}}$ Or $\dfrac{1\,mol\,CaC{{l}_{2}}}{2\,mol\,Cl}$
This shows that for the production of 1 mole of calcium chloride, 2 mole of chlorine is needed always.
Now, through the unitary method, we will get the number of moles that are required for obtaining 2.7 mole of calcium chloride.
Number of moles of chlorine= 2.7 moles $CaC{{l}_{2}}\times \dfrac{2\,moles\,Cl}{1\,mole\,CaC{{l}_{2}}}$
Number of moles of chlorine= 5.4 moles
So, 5.4 moles of chlorine is required to obtain 2.7 moles of calcium chloride.

Additional Information:
Calcium chloride is very useful for the human body as it treats the condition of dehydration when added with water.

Note:
When dealing with stoichiometric calculations, always look upon the relationship between the quantity which we have to find, and the quantity which is given. Like quantity of calcium is not considered in this answer as we are asked to find chlorine, so the relationship of chlorine is considered with calcium chloride.