Chapter 18, Problem 18.49SP

(a)

Interpretation Introduction

Interpretation:

The density of hydrogen in $LiH$ and the number of hydrogen atoms in $5c{m}^{3}ofLiH$ has to be given.

Concept introduction:

Density of a substance:

Density can be calculated by using following formula,

$Density=\frac{mass}{volume}$

Number of moles calculated by using following formula,

$\text{Number}\text{of}\text{moles}\text{=}\frac{\text{mass}}{\text{molar}\text{mass}}$

(b)

Interpretation Introduction

Interpretation:

The volume of hydrogen at $20°Cand740mmHg$ which are required to make $5c{m}^{3}ofLiH$ has to be calculated.

Concept introduction:

Ideal gas Equation:

Any gas is described by using four terms namely pressure, volume, temperature and the amount of gas. Thus combining three laws namely Boyle’s, Charles’s Law and Avogadro’s Hypothesis the following equation could be obtained. It is referred as ideal gas equation.

$\begin{array}{l}\text{V }\propto \frac{\text{nT}}{\text{P}}\\ \text{V = R}\frac{\text{nT}}{\text{P}}\\ \text{PV = nRT}\end{array}$

Where,

$\begin{array}{l}\text{n = moles}\text{of}\text{gas}\\ \text{P = pressure}\\ \text{T = temperature}\\ \text{R = gas }\text{constant}\end{array}$