Question

If $5.0gm$of $BaC{{l}_{2}}$is present in ${{10}^{6}}gm$solution, the concentration is
A.$1\,ppm$
B.$5\,ppm$
C.$50\,ppm$
D.$1000\,ppm$

Answer 1

Hint: In solution, the concentration is the amount of solute dissolved in the solution of volume in $litre$or the solvent in $kg$. Concentration can be in terms of parts per million or $ppm$. Here we have to calculate the concentration in terms of $ppm$ by putting the given values in the respective formulas that are provided below.

Formula Used:Concentration in terms of $ppm$ $=\dfrac{mass\,\,of\,solute\,}{total\,\,mass\,\,of\,\,the\,\,solution}\times {{10}^{6}}$

Complete answer:In this problem, a definite amount of solute $BaC{{l}_{2}}$ is dissolved in a large mixture solution of mass${{10}^{6}}gm$. Here $ppm$ parts per million are best to describe the concentration of any large mixture solution. It is expressed as $1$in $1\,million$ or ${{10}^{6}}$.
There are various procedures to calculate the concentration of any solution. Generally, the concentration of any solution can be represented by the ratio of the mass of the solute to the total mass of the solution.
 $\therefore $The concentration of any solution $=\dfrac{Weight\,\,of\,\,solution}{Volume\,\,in\,\,litre}$
As the given mass of the solution is very large, therefore concentration $ppm$will be a suitable way.
Given the mass of the solute, $BaC{{l}_{2}}=5.0g$
And the total mass of the solution $={{10}^{6}}gm$
$\therefore $ Concentration in$ppm=\dfrac{mass\,\,of\,solute\,}{total\,\,mass\,\,of\,\,the\,\,solution}\times {{10}^{6}}$
Or, Concentration$=\dfrac{5.0\,gm\,}{{{10}^{6}}gm}\times {{10}^{6}}=5.0\,ppm$

Thus, option (B) is correct.

Additional information: To know the exact concentration of a solution we need to know the exact amount of solute in terms of grams or moles and the mass of solvent or volume of solution. There are also other ways of expressing the concentration such as molarity, normality, mole fraction, mass percentage, and volume percentage.

Note: In chemistry especially in physical chemistry or other branched subjects mole concept is a very important fundamental concept. The given problem is also based on the mole concept. So, one should understand the concept of mole very well to deal with any problem related to this concept.