Q. 7.79 - An Introduction to General, Organic, and Biological Chemistry

Question

Using the models of the molecules (black = C, white = H, yellow = S, green = Cl), determine each of the following for compounds $1$and $2$:

(a) Molecular formula.

(b) Molecular mass.

(c) No of moles in$10 g$ .

Step-by-Step Solution

Answer

(a) Molecular formula of compounds are $S_{2}C{l}_2 and C_6{H}_6$

(b) Molecular mass of compounds $135 and 78$

(c) No of moles  in $10 g$are  $0.074 \mathrm{and} 0.128$.

Part (a) Step 1: Given Information

We need to find the molecular formula of molecules.

Part (a) Step 2: Explanation

Molecular formula gives information about number of moles of different atoms in a molecule.

If we see the figure then we identify that :

The molecular formula is  $S_{2}C{l}_2$$and C_6{H}_6$.

Because there are two green atoms represents the chlorine and yellow sphere represents the Sulphur and same as second compound.

Part (b) Step 1: Given Information

We need to find the molar mass of compounds. 

Part (b) Step 2: Explanation

let  $m_1 and m_2$are molar masses of ${\mathrm{S}}_2{\mathrm{Cl}}_2 \mathrm{and} {\mathrm{C}}_6{\mathrm{H}}_6$

$$\begin{gathered} {\mathrm{m}}_1 = 32 \left(\mathrm{amu}\right)\times 2+35.5 \left(\mathrm{amu}\right)\times 2 \\ {\mathrm{m}}_1 = 135 \mathrm{amu} \\ {\mathrm{m}}_2 = 12 \left(\mathrm{amu}\right)\times 6+6\times 1 \left(\mathrm{amu}\right) \\ {\mathrm{m}}_2 = 78 \mathrm{amu} \end{gathered}$$

Part (c) Step 1: Given information

We need to find the no of moles present in $10 g$.

Part (c) Step 2: Explanation

let $n_1$ and  $n_2$are moles of molecules

$$\begin{gathered} {\mathrm{n}}_1 = \frac{10 \mathrm{g}}{135 \mathrm{amu}} \\ {\mathrm{n}}_1 =0.074 \mathrm{mole} \\ {\mathrm{n}}_2 = \frac{10 \mathrm{g}}{78 \mathrm{amu}} \\ {\mathrm{n}}_2 = 0.128 \mathrm{mole} \end{gathered}$$