Question

A solution contains \[\text{20 g}\] of salt in a \[\text{500 mL}\] solution. Calculate the concentration in terms of mass by volume percentage.
A.0
B.20
C.1
D.4

Answer 1

Hint:The concentration of a solution can be expressed in different units and the mass by volume percentage in the defined as the mass of the solute dissolved in \[\text{100 mL}\] volume of the solution expressed in \[\text{g/mL}\].

Complete step by step answer:
Given that the mass of the solute, which is salt = \[\text{20 g}\]
The volume of the solution = \[\text{500 mL}\]
According to the definition, the formula for mass by volume percentage can be written as = $\dfrac{\text{mass}}{\text{volume}}\text{ }\times\text{ 100}$.
Putting the values of the mass and the volume in the above equation we get,
Mass by volume percentage = $\dfrac{20}{500}\text{ }\times\text{ 100 = 4 }%\text{ }$

Therefore, the correct answer is option D.
Note:
The concentration of the solution can be expressed in different units. The weight by weight percentage expresses the concentration of the solution as the ratio of the weight of solute by the weight of the solution. The weight by volume percentage expresses the concentration of the solution as ratio of the weight of the solute present in\[\text{100 mL}\]of the solution.
Considering the moles of the solute, the number of moles of the solute present per litre of the solution is defined as the molarity of the solution. Again if the weight of the solvent is considered then the ratio of the number of moles of the solute present per Kg of the solvent is defined as the molality of the solution. The mole fraction of the solute is defined as the number of moles by the sum of the number of moles of the solute and the number of moles of the solvent.