Chapter 10, Problem 101A

Interpretation Introduction

Interpretation:

The number of chlorophyll molecules present in $1{\text{ cm}}^2$ should be calculated.

Concept introduction:

Number of moles of a compound is defined as the ratio of given mass of the compound to the molar or molecular mass of the compound.

The mathematical expression is given by:

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

The one mole of any substance is equal to the Avogadro number i.e. $6.022\times {10}^{23}$ atoms.

Answer to Problem 101A

The number of chlorophyll molecules present in $1{\text{ cm}}^2$

$=9.033\times {10}^{18}{\text{ molecules/cm}}^2$

Explanation of Solution

Since, one mole of any substance is equal to the Avogadro number i.e. $6.022\times {10}^{23}$ atoms.

Number of moles of chlorophyll per cm² = $1.5\times {10}^{-5}\text{ mole}$

Number of molecules = $\text{number of moles ×}\frac{6.022\times 10\text{molecules}}{1\text{ mole}}$

Thus, number of chlorophyll molecules present in $1{\text{ cm}}^2$

= $1.5\times {10}^{-5}{\text{ mole/cm}}^{\text{2}}\times \frac{6.022\times 10\text{molecules}}{1\text{ mole}}$

$=9.033\times {10}^{18}{\text{ molecules/cm}}^2$