Question:

63g of a compound (Mol.Wt.=126) was dissolved in 500g of distilled water.The density of the resultant solution is 1.126g/ml. The molarity of the solution is

Updated On: Jun 24, 2024
  • 1.25M
  • 1.0M
  • 0.75M
  • 1.1M
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The Correct Option is B

Solution and Explanation

To find the molarity of the solution, we first need to calculate the number of moles of the compound and then use the formula for molarity.
Given:
- Mass of compound = 63 g
- Molecular weight of compound = 126 g/mol
- Mass of water = 500 g
- Density of solution = 1.126 g/ml
First, let's find the volume of the solution. The density formula is \( \text{density} = \frac{\text{mass}}{\text{volume}} \), so the volume of the solution is:
\[ \text{Volume of solution} = \frac{\text{mass of solution}}{\text{density of solution}} = \frac{63 g + 500 g}{1.126 g/ml} \]
\[ \text{Volume of solution} = \frac{563 g}{1.126 g/ml} \]
\[ \text{Volume of solution} = 500 ml \]
Since the density of water is 1 g/ml, the mass of water in the solution is 500 g. This means the mass of the compound in the solution is \( 63 \text{ g} \). Since the compound's molecular weight is 126 g/mol, the number of moles of the compound in the solution is:
\[ \text{Moles of compound} = \frac{\text{Mass of compound}}{\text{Molecular weight of compound}} \]
\[ \text{Moles of compound} = \frac{63 \text{ g}}{126 \text{ g/mol}} \]
\[ \text{Moles of compound} = 0.5 \text{ mol} \]
Now, the molarity of the solution is given by the formula:
\[ \text{Molarity} = \frac{\text{Moles of solute}}{\text{Volume of solution in liters}} \]
Since we have 0.5 moles of compound and the volume of the solution is 500 ml (0.5 liters), the molarity is:
\[ \text{Molarity} = \frac{0.5 \text{ mol}}{0.5 \text{ L}} \]
\[ \text{Molarity} = 1.0 \text{ M} \]
Therefore, the molarity of the solution is 1.0 M.
The correct answer is option (B): 1.0M
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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:

  1. Unsaturated Solution- A solution in which more solute can be dissolved without raising the temperature of the solution is known as an unsaturated solution.
  2. 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.
  3. Supersaturated Solution- A solution that contains more solute than the maximum amount at a certain temperature is known as a supersaturated solution.