Question

with ge help of vapour pressure temperature curves for solution and solvent explain why boiling point of solvent is elevated when non volatile solute is dissolve in it​

Answer 1

Answer:

A nonvolatile solute has a vapor pressure of zero, so the vapor pressure of the solution is less than the vapor pressure of the solvent. Thus, a higher temperature is needed for the vapor pressure to reach the surrounding pressure, and the boiling point is elevated.

Answer 2

The presence of a non-volatile solute in a solvent decreases the vapour pressure of the solvent, leading to an increase in the boiling point of the solution. This effect can be understood through the use of vapour pressure-temperature curves for the solution and solvent, which show the relationship between boiling point and solute concentration.

• The vapour pressure of a liquid is the pressure exerted by its vapours when it is in equilibrium with its liquid phase at a given temperature.
• When a solute is added to a solvent, the vapour pressure of the solvent decreases. This is because the solute molecules occupy some of the surface area of the solvent and interfere with its ability to evaporate.
• As a result, the boiling point of the solvent is raised because more heat is required to increase its vapour pressure to the point where it equals the atmospheric pressure.
• The degree of boiling point elevation is directly proportional to the concentration of the solute in the solution. Therefore, the more solute that is dissolved in the solvent, the greater the increase in boiling point.
• The relationship between boiling point elevation and solute concentration can be represented by a vapour pressure-temperature curve for the solution, which is different from that of the pure solvent.
• The curve for the solution is shifted upwards compared to the curve for the solvent due to the decrease in vapour pressure caused by the solute.
• The boiling point of the solution is where the curve intersects the atmospheric pressure line. Since the curve for the solution is higher than that of the pure solvent, the boiling point of the solution is higher than that of the pure solvent.

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