Vapour Pressure and Boiling Point

The vapour pressure of a liquid is the pressure exerted by its vapour in equilibrium with the liquid at a given temperature. It is a measure of how easily the liquid molecules escape from the liquid phase and enter the vapour phase. The boiling point of a liquid is the temperature at which its vapour pressure equals the external pressure.

Given Data:
Vapour pressure at 300K = 300 mm Hg
Vapour pressure at 350K = 570 mm Hg

Determining the Normal Boiling Point:
To determine the normal boiling point of the liquid, we need to find the temperature at which the vapour pressure equals 760 mm Hg (standard atmospheric pressure).

Using the Clausius-Clapeyron equation:
The Clausius-Clapeyron equation relates the vapour pressure of a substance at two different temperatures. It is given by:

ln(P1/P2) = -(ΔHvap/R) * (1/T1 - 1/T2)

where P1 and P2 are the vapour pressures at temperatures T1 and T2, ΔHvap is the enthalpy of vaporization, and R is the ideal gas constant.

Calculating the enthalpy of vaporization:
Let's assume the enthalpy of vaporization is ΔHvap.

From the given data:
ln(300/570) = -(ΔHvap/R) * (1/300 - 1/350)

Simplifying the equation:
ln(0.5263) = -ΔHvap/R * (0.003333 - 0.002857)
ln(0.5263) = -ΔHvap/R * (0.000476)
ln(0.5263) = -ΔHvap/R * 0.000476
ln(0.5263) = -ΔHvap/R * 0.000476

Determining the boiling point:
Now that we have calculated the enthalpy of vaporization, we can use it to find the boiling point.

ln(760/570) = -(ΔHvap/R) * (1/Tb - 1/350)

Simplifying the equation:
ln(1.3333) = -ΔHvap/R * (1/Tb - 0.002857)
ln(1.3333) = -ΔHvap/R * (1/Tb - 0.002857)

We can solve this equation to find the value of (1/Tb - 0.002857).

Once we have (1/Tb - 0.002857), we can rearrange the equation to find the boiling point (Tb).

In conclusion:
To determine the normal boiling point of the liquid, we can use the Clausius-Clapeyron equation and the given vapour pressure data at different temperatures. By calculating the enthalpy of vaporization and rearranging the equation, we can find the boiling point at which the vapour pressure equals 760 mm Hg.