Chapter 10, Problem 99A

Interpretation Introduction

Interpretation:

The number of moles of water present in snowflakes 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 99A

The number of moles of water present in snowflakes = $3.16\times {10}^{-6}\text{ moles}$.

Explanation of Solution

Number of molecules of water present in snowflakes = $1.9\times {10}^{18}\text{ molecules}$

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

Thus, number of moles of water = $1.9\times {10}^{18}\text{ molecules}\times \frac{1\text{ mole}}{6.022\times 10\text{molecules}}$

= $3.16\times {10}^{-6}\text{ moles}$