Chapter 3, Problem 3.25P

(a)

Interpretation Introduction

Interpretation:

The amount of compound in $285.3\text{ g}$ of cisplatin is to be determined.

Concept introduction:

Molar mass is defined as the mass of $1\text{ mol}$ of a chemical substance in grams. The molar mass of a compound is calculated by the addition of the molar mass of each element multiplied by its number of atoms present in the chemical formula.

The mass and molar mass of a chemical substance are used to calculate the amount of substance. The expression to calculate the amount of a substance is as follows:

$\text{Amount }\left(\text{mol}\right)=\left(\text{Mass }\left(\text{g}\right)\right)\left(\frac{\text{1 mol}}{\text{no}\text{. of grams}}\right)$ (1)

(b)

Interpretation Introduction

Interpretation:

In $0.98\text{ mol}$ of cisplatin, the number of hydrogen $\left(\text{H}\right)$ atoms is to be calculated.

Concept introduction:

One mole is defined as the amount of substance that contains the same number of entities such as molecules, ions, atoms as the number of atoms in $12\text{ g}$ of $\text{C-12}$. This number is called Avogadro’s number. The value of Avogadro’s number is $\text{6}\text{.022}\times {\text{10}}^{23}\left(\text{entitites/mol}\right)$.

Molar mass is defined as the mass of $1\text{ mol}$ of a chemical substance in grams. The molar mass of a compound is calculated by the addition of the molar mass of each element multiplied by its number of atoms present in the chemical formula.

The molecular formula of a compound tells the number of atoms/ions of each element present in the compound.

Following are the steps to calculate the number of atoms in a compound.

Step 1: Determine the number of moles of atoms of an element from the molecular formula of the compound. The formula to calculate the moles of atoms of an element A is as follows:

$\text{Amount of atoms of element A}\left(\text{mol}\right)=\left(\begin{array}{l}\text{amount of}\\ \text{compound}\\ \left(\text{mol}\right)\end{array}\right)\left(\frac{\begin{array}{l}\text{moles of atoms of}\\ \text{element A in}\\ \text{molecular formula}\end{array}}{1\text{ mol compound}}\right)$ (4)

Step 2: Determine the number of atoms by multiplying the amount of atoms with the Avogadro’s number. The expression to calculate the number of atoms of an element is as follows:

$\text{Number of atoms}=\left(\text{Amount }\left(\text{mol}\right)\right)\left(\frac{6.022\times {10}^{23}\text{ atoms}}{1\text{ mol}}\right)$ (5)