Question

The concentration of a 100 ml solution containing X grams of $N{{a}_{2}}C{{O}_{3}}$ (mol.wt. = 106) is Y M. The values of X and Y are respectively:

Answer 1

Hint: The concept of the physical chemistry that includes the formula to calculate the actual concentration that is Concentration $C = \dfrac{m}{V(litre)}$ leads you to the required answer.

Complete Solution : In the physical chemistry concepts from the lower classes, we have studied about the calculation of molarity, molality, mole fraction and concentration and many other parameters by carrying out the experiments.
- Now, let us focus on the calculation of concentration and this calculation leads us to the required answer.
- We have come across the term concentration and the formula used for this calculation is that the concentration is the ratio of mass of the solute to that of the solution.
- If we need this value in terms of percentage then the above said ratio is multiplied by the value ${{10}^{2}}$
If the value is needed in terms of ppm, the ratio is multiplied by ${{10}^{6}}$
And if the value is needed in terms of ppb, then the ratio is multiplied by ${{10}^{9}}$
- But here, since we need the value in terms of molarity, the ration will be moles of solute to that of solution in litres.
- Thus, accordingly this formula can be written as $C=\dfrac{m}{V(litre)}$
where m is the number of moles of solute
and V is the volume of solution in litres.
Here, there are two solutes that are X and Y.
Therefore, the ratio will be, $ concentration 'Y' = \dfrac{\left( \dfrac{X}{106} \right)}{\left( \dfrac{100}{1000} \right)}$
Simplifying this, we have$106Y = 10X$
In terms of grams we divide both sides by 100
\[\Rightarrow 1.06X = 0.1Y\]
Thus,$\dfrac{X}{Y} = \dfrac{0.1}{1.06}$
Therefore, the correct answer is, the values of X and Y are 0.1g and 1.06g respectively.

Note: Note that during the calculation of concentration be sure of the question asked and go through it thoroughly as to in which form the question is being asked that is, ppm (parts per million) or ppb (parts per billion) or any other worm and do not mark wrong answers.