Question

In $500$ grams of water dissolved $2$ moles of potassium sulfate the mass percentage of salt in solution:
A)$41\%$
B)$60\%$
C)$35\%$
D)$48\%$

Answer 1

We can calculate the mass percentage of the solution using the formula,
${\text{Mass}}\% = \dfrac{{{\text{Mass of the components in the solution}}}}{{{\text{Total mass of the solution}}}} \times 100$

Complete step by step answer: Given,
The number of moles of potassium sulfate is $2mol.$
The number of grams of water is $500gm$.
We know that the molecular weight of potassium sulfate is $174.25gm$.
Now, we calculate the mass of potassium sulfate dissolved is calculated as,
Mass of potassium sulfate dissolved$= 2 \times 174.25 = 348.5gm$
Now, we calculate the mass percentage of the solution as,
${\text{Mass}}\% = \dfrac{{{\text{Mass of the components in the solution}}}}{{{\text{Total mass of the solution}}}} \times 100$
${\text{Mass}}\% = \dfrac{{348}}{{500 + 348}} \times 100 = 41.07\%$
The obtained value is closely agreed with option A.

Therefore, the option A is correct .

Note: Now we discuss how mass percent and percentage composition are differ from each other.
Mass percent may be a way of expressing a degree or describing the component during a particular mixture. The solution composition is usually described in mass percentage which shows the mass of solute present during a given mass of solution. The number of solutes is expressed in mass or by moles. For a solution, the mass percent is described because the grams of solute per grams of solution, multiplied by $100$ to induce the percentage.
The percentage composition of a given compound is defined because the ratio of the quantity of every element to the entire amount of individual elements present within the compound multiplied by $100$. Here, the number is measured in terms of grams of the weather present. The percent composition of any compound expresses its composition in terms of all the weather present. Thus, it helps in qualitative analysis of the given compound.