Question

The saturated vapour pressure of water at $\text{10}{{\text{0}}^{\text{o}}}\text{C}$ is?
A) 750mm of Hg
B) 760mm of Hg
C) 76 mm of Hg
D) 7.6mm of Hg

Answer 1

Hint At NTP i.e. normal temperature and pressure, the pressure is taken as 1 atm. And the temperature at normal temperature is taken as ${{0}^{\text{o}}}\text{C=273K}$
At mm Hg means the height to which the Mercury column has raised due to the pressure applied.

Complete step by step solution:
Now let’s see the requirement of the question, here it is given as the saturated vapour pressure of water at ${{100}^{\circ }}C$should be found out.
Before approaching the answer, let’s discuss some of the terms related with this question for more clarifications.
First we will see what is meant by saturated vapour pressure.
-Saturation vapour pressure simply can be said as the vapour pressure of a saturated system, i.e. the vapor pressure of a system at given in which the vapors of a substance is in equilibrium with the surface of solid or liquid phase which has attained a saturation level but not super saturation.
Now we have to consider the NTP which is normal temperature and pressure.
The normal temperature is ${{\text{O}}^{\text{o}}}\text{C=273K}$
The normal pressure is 1 atm.
We use NTP for many calculations involving the gaseous phase
So saturated vapour pressure for water given is equal to ${{100}^{\circ }}C$, which is the boiling point of water.
We consider the NTP, for solving this problem we consider NTP conditions,
At normal temperature, we take the value of pressure as 1 atm.
And we know that the value of 1 atm is equal to 76 cm Hg i.e. 760 mm Hg.

So from the above options given the correct answer is option (B).

Note: For solving such problems we should know the STP and NTP values,
STP-Standard Temperature and Pressure,
Temperature,$\text{T=}{{\text{0}}^{\text{o}}}\text{C=273K}$
Pressure=1 bar
NTP-Normal Temperature and Pressure
Temperature,$\text{T=}{{\text{0}}^{\text{o}}}\text{C=273K}$
Pressure, P = 1 atm
And we should know the conversions to carry out the mathematical calculations