Question

The molar mass of copper chloride, $CuC{{l}_{2}}$ is $134 gmo{{l}^{-1}}$ . How many formula units of $CuC{{l}_{2}}$ are present in $17.6 g$ of $CuC{{l}_{2}}$ ?

Answer 1

Hint: Mole concept gives the relationship between the number of moles, weight and molar mass of the compound. Molar mass is calculated by adding up the atomic masses of the element combined to form a molecule.

Complete answer:
Here, it is given that the molar mass of copper chloride is $134g mo{{l}^{-1}}$
Weight of copper chloride is $17.6 g$
Now, we use mole formula to calculate moles of copper chloride.
$n=\dfrac{w}{m}$
Where, $n$ is the number of moles, $w$ is the weight of the compound and $m$ is the molar mass of the compound.
Now, we substitute the value in the given formula we get,
$n=\dfrac{17.6}{134}$
$n=0.131mol$
Using unitary method we calculate the formula units of $CuC{{l}_{2}}$
 $1mole$ of $CuC{{l}_{2}}$ contains $6.022\times {{10}^{23}}$ formula units
$0.131moles$ of $CuC{{l}_{2}}$ contains $\dfrac{6.022\times {{10}^{23}}}{1}\times 0.131$
$0.131moles$ of $CuC{{l}_{2}}$ contains $7.90\times {{10}^{22}}$ formula units.
Formula units of $CuC{{l}_{2}}$present in $17.6g$ of $CuC{{l}_{2}}$are $7.90\times {{10}^{22}}$ formula units.

Additional information:Moles are defined as a scientific unit which is used to measure large quantities of atoms and molecules. It is defined as the amount of substance present in a sample.
$1mole=6.022\times {{10}^{23}}particles$
This is also called Avogadro's number $\left( {{N}_{A}} \right)$ .
Molar mass is defined as the addition of atomic mass of atoms, combined in a molecule. Here, the molar mass of $CuC{{l}_{2}}$ is $134gmo{{l}^{-1}}$ .
Moles are defined as the weight of the compound per molar mass of the compound.
Formula mass is different from molecular mass. In formula mass, there is an addition of atomic masses of ion present in an ionic compound, whereas molecular mass is the addition of atomic masses of the atoms in a molecule.

Note: The molar mass is calculated in $gmo{{l}^{-1}}$ .
You should know how to calculate molar mass of a compound and then substitute the values in the mole concept formula.