Chapter 6.1, Problem 3RQ

(a)

Interpretation Introduction

Interpretation :

A mole of any substance contains Avogadro’s number of units. An equivalent statement of this must be given.

Concept Introduction :

Avogadro’s number is $6.023\times {10}^{23}.$

Answer to Problem 3RQ

Avogadro’s ( $6.023\times {10}^{23}$ ) number of units of any substance is 1 mole.

Explanation of Solution

  $6.023\times {10}^{23}$ number of electrons means 1 mole electron.

  $6.023\times {10}^{23}$ number of protons means 1 mole proton.

  $6.023\times {10}^{23}$ number of ions means 1 mole ion.

b)

Interpretation Introduction

Interpretation :

Possible conversion factors must be written from this relationship.

Concept Introduction :

Mole of any substance can be converted to number of units just by multiplying with Avogadro’s number.

Number of units of any substance can be converted to moles just by dividing with Avogadro’s number.

Answer to Problem 3RQ

Two possible conversion factors are $\frac{1}{6.023\times {10}^{23}}\text{ and }6.023\times {10}^{23}.$

Explanation of Solution

If x number of atoms needed to be converted to mole then it can be written as mole $=x\times \frac{1}{6.023\times {10}^{23}}\text{.}$

If number of units present x mole is required then it can be written as number of units $\text{=}x\times 6.023\times {10}^{23}.$

c)

Interpretation Introduction

Interpretation :

The conversion factor used to determine moles Al from atoms Al and atoms Au from moles Au must be explained.

Concept Introduction :

To get number of atoms from moles of any element Avogadro’s number is multiplied with the number of moles. To get number of moles from number of atoms of an element, the number of atoms is divided with Avogadro’s number.

Answer to Problem 3RQ

Moles of Al atom $\text{=}\frac{\text{Number of Al atoms}}{\text{6}{\text{.023×10}}^{\text{23}}}\text{. }$

Atoms of Au $\text{=moles of Au}\times 6.023\times {10}^{23}.$

Explanation of Solution

Using conversion factor $\frac{1}{\text{6}{\text{.023×10}}^{\text{23}}}$ moles of Al is found from number of Al atoms.

Similarly using conversion factor $6.023\times {10}^{23}$ number of Au atoms is found from moles of au.