Chapter 2, Problem 2.12P

(a)

Interpretation Introduction

Interpretation:

The density of Helium should be calculated.

Concept introduction:

Ideal gas law:

The equation, which is equating the product of volume of one mole gas and pressure to the product of gas constant and thermodynamic temperature.

$\text{PV=}\text{nRT}$

The above equation is known as ideal gas law or ideal gas equation and all ideal gases are obey this equation but made a good approximation to real gas.

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,

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

(b)

Interpretation Introduction

Interpretation:

The true mass of Sodium 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.