Q3.1P - Chemistry: Molecular Nature Of Matter And Change

Question

The atomic mass of $\mathbf{CI}$ is 35.45 amu, and the atomic mass of $\mathbf{AI}$  is 26.98 amu. What are the masses in grams of 3 mol of  $\mathbf{AI}$ atoms and of 2 mol of  $\mathbf{CI}$ atoms?

Step-by-Step Solution

Answer

The mass of $\mathbf{AI}$ is 80.94 grams.

The mass of $\mathbf{CI}$ is 70.9 grams.

Step 1: Relation between mass and number of moles

The number of moles is calculated by the mass and Molar mass. The relationship between the number of moles, mass, and molar mass is given below.

$\mathbf{Number}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{moles}\mathbf{=}\frac{\mathbf{mass}}{\mathbf{Molarmass}}$

Step 2: Calculate the mass of AI

The molar mass of  $\mathbf{AI}$= 26.98 amu = 26.98 g/mol

The number of moles of $\mathbf{AI}$ = 3 mol

Thus, the mass of $\mathbf{AI}$ is:

   $$\begin{gathered} \mathrm{mass} \mathrm{of} \mathrm{Al}=\mathrm{moles} \mathrm{of} \mathrm{Al}\times \mathrm{Molarmass} \mathrm{of} \mathrm{Al} \\ =3 \mathrm{mol}\times 26.98\mathrm{g}/\mathrm{mol} \\ =80.94 \mathrm{g} \end{gathered}$$

Step 3: Calculate the mass of CI

The molar mass of  = 35.45 amu = 35.45 g/mol

The number of moles of  = 2 mol

Thus, the mass of  is:

$$\begin{gathered} \mathrm{mass} \mathrm{of} \mathrm{Cl}=\mathrm{moles} \mathrm{of} \mathrm{Cl}\times \mathrm{Molarmass} \mathrm{of} \mathrm{Cl} \\ =2 \mathrm{mol}\times 35.45 \mathrm{g}/\mathrm{mol} \\ =70.90" \hspace{0.33em}\mathrm{g}) \end{gathered}$$