Question

What is the concentration in grams per litre of a solution made by adding water to $6$ moles of $CaC{{l}_{2}}$ to make $4$ litres of solution?

Answer 1

Here, our solute is calcium chloride which contains calcium and chloride. So, first of all we are going to calculate the molar mass of the solute by putting the molecular mass of calcium and chloride followed by the calculation of concentration.
Formula to be used:
The concentration of a solution can be calculated by using the formula:
Concentration = $\dfrac{Mass\text{ }of\text{ }solute}{Volume\text{ }of\text{ }solution}$
The unit of concentration here will be $g/L$

Complete answer:
Calcium chloride ($CaC{{l}_{2}}$) is an inorganic compound which is a white powder or white coloured crystalline solid. It is completely odourless and its solubility in water is very high.
Grams per liters generally represent the mass of a solute which is divided by the volume of solution (liters). This measure of concentration is mostly used when we discuss about the solubility of a solid in the solution.
By the term molar mass, we mean that any substance with the mass in grams of one mole of representative particles of that substance. Here, the representative particles can be anything like atoms, molecules or formula units of the ionic compounds.
The term molarity of a solution means the number of moles of a solute dissolved in one liter of the solution.
First of all we have to calculate the molar mass of solute ($CaC{{l}_{2}}$):
Molecular mass of Ca = $1*40.07$
=$40.07$ $g/mol$
Molecular mass of $C{{l}_{2}}$ = $2*35.45$
=$70.9$ $g/mol$
Molecular mass of $CaC{{l}_{2}}$ = $40.07+70.9$
=$110.97$ $g/mol$

So, mass of $6$moles of $CaC{{l}_{2}}$= $6mol$ $*$ $110.97$ $\dfrac{g}{mol}$
=$665.8g$
Volume of the solution given is= $4L$
So, the concentration of solution will be:
Concentration = $\dfrac{Mass\text{ }of\text{ }solute}{Volume\text{ }of\text{ }solution}$
Concentration=$\dfrac{665.8g}{4L}$
So, the concentration=$166.47g/L$
Therefore, the concentration of a solution made by adding water to $6$moles of $CaC{{l}_{2}}$ to make $4$ litres of solution is $166.47g/L$

Note:
Be very careful with the equations and calculations involved in these types of questions. Here the concept of molarity has been used so give extra attention to the units as well and try to remember the molecular masses of elements to make the process easier.