Question:
1.00 g of a non-electrolyte solute dissolved in 50 g of benzene lowered the freezing point of benzene by 0.40 K. The freezing point depression constant of benzene is $5.12 \,K \,kg\, mol^{-1}$. The molar mass of the solute is
1.00 g of a non-electrolyte solute dissolved in 50 g of benzene lowered the freezing point of benzene by 0.40 K. The freezing point depression constant of benzene is $5.12 \,K \,kg\, mol^{-1}$. The molar mass of the solute is
Updated On: Jun 23, 2023
- 256 kg/mol
- 256 g mol
- 256 g/mol
- 256 mg/mol
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The Correct Option is C
Solution and Explanation
We have $M_{2} = \frac{K_{f} \times w_{2}\times1000}{\Delta T_{f} \times w_{1}}$
where $w_{1} =$ weight of solvent $= 50\, g$
$w_{2} =$ weight of solute $= 1.00 \,g$
$K_{f } =$ molal depression constant $= 5.12\, K\, kg \,mol^{-1}$
Substituting the values of various terms involved in the above equation, we get
$M_{2} = \frac{5.12\times1.00\times1000}{0.40\times50} = 256 \,g \,mol^{-1}$
Thus, molar mass of the solute $= 256\, g \,mol^{-1}.$
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Concepts Used:
Solutions
A solution is a homogeneous mixture of two or more components in which the particle size is smaller than 1 nm.
For example, salt and sugar is a good illustration of a solution. A solution can be categorized into several components.
Types of Solutions:
The solutions can be classified into three types:
- Solid Solutions - In these solutions, the solvent is in a Solid-state.
- Liquid Solutions- In these solutions, the solvent is in a Liquid state.
- Gaseous Solutions - In these solutions, the solvent is in a Gaseous state.
On the basis of the amount of solute dissolved in a solvent, solutions are divided into the following types:
- Unsaturated Solution- A solution in which more solute can be dissolved without raising the temperature of the solution is known as an unsaturated solution.
- Saturated Solution- A solution in which no solute can be dissolved after reaching a certain amount of temperature is known as an unsaturated saturated solution.
- Supersaturated Solution- A solution that contains more solute than the maximum amount at a certain temperature is known as a supersaturated solution.