Chapter 2, Problem 2.13P

(a)

Interpretation Introduction

Interpretation:

The vapour pressure of water in the air at 20°C should be calculated.

Concept introduction:

Equilibrium vapour pressure:

The equilibrium vapour pressure is nothing but the pressure refer to the equilibrium between liquid and vapour.

The product of relative humidity with given pressure to give

(b)

Interpretation Introduction

Interpretation:

At the given condition, the density of air should be calculated.

Concept introduction:

Density:

Density of a substance is defined as the three dimensional space or area occupied by quantity of the substance. That is mass of the substance that occupies per unit volume of the three dimensional space (which includes dimensions of area and height).  It is expressed as,

$\text{ρ=}\frac{\text{Mass}}{\text{Volume}}$

(c)

Interpretation Introduction

Interpretation:

The true mass of Water should be calculated.

Concept introduction:

Buoyancy Correction:

The weight of the object in air is less then weight of the object in vacuum because of buoyancy, this weight variation is corrected using Buoyancy equation it is,

$\text{m}\text{=}\frac{\text{m'}\left(\text{1-}\frac{{\text{d}}_{\text{a}}}{{\text{d}}_{\text{w}}}\right)}{\left(\text{1-}\frac{{\text{d}}_{\text{a}}}{\text{d}}\right)}$

Where,

$\text{m}$ is mass of object in vacuum.

$\text{m'}$ is mass of object in air (read on a balance).

${\text{d}}_{\text{a}}$ is the density of air $\left(\text{0}\text{.001 2 g/mL near I bar and 25°C}\right)$.

${\text{d}}_{\text{w}}$ is the density of calibration weights $\text{(8}\text{.0 g/mL)}$.

$\text{d}$ is the density of the object being weighed.